Abstract book

First EMBO Conference on Aquatic – SAME13

Abstract book

First EMBO Conference on Aquatic Microbial Ecology – SAME13

Editors: Amalfitano S, Coci M, Corno G, Luna GM

SAME13 secretariat: Institute of Ecosystem Study (CNR-ISE) - Largo Tonolli 50, 28922 Verbania (Italy) www.same13.eu - [email protected] Published by Microb&CO, Microbial Ecology Services - viale XX Settembre 45, 95128 Catania (Italy) www.microbeco.org - [email protected] ©2013 Ass. Microb&co, Stresa, Italy, ISBN: 9788890971419

1

Tube …a microbiological ditty

In one Test Tube

two billion beings

vie and tumble

in a life giving medium

Their paths random

aimless and jagged

discontinuous motion

Their numbers growing

exponentially

to the outermost limit

of their bounded Universe

My hand does not tremble

as I pour their Cosmos

into the Sterilizer

Tom Berman (1934-2013)

From “Shards” published 2002

2 TABLE OF CONTENTS

WELCOME TO STRESA ...... 4 SAME13 COMMITTEES ...... 5 GENERAL INFORMATION ...... 6 DESTINATION STRESA ...... 7 SOCIAL EVENTS ...... 8 MID-SAME OPTIONAL EXCURSIONS ...... 9 INFORMATION FOR PRESENTERS ...... 11 SAME13 BEST PRESENTATION PRIZES ...... 11 KEYNOTE SPEAKERS ...... 12 CONFERENCE VENUE ...... 15 SAME13 GENERAL PROGRAM ...... 16 ORAL PLENARY SESSIONS ...... 22 OS-1A. Ecological consequences of global change in aquatic ecosystems ...... 25 OS-2A. Bacterial diversity: from community composition to community functions ...... 30 OS-3. Phototrophic as the movers and shakers in aquatic ecosystems ...... 37 OS-1B. Ecological consequences of global change in aquatic ecosystems ...... 42 OS-4. Bacterial life strategies in relation to carbon flow to higher trophic levels ...... 48 OS-5. Giving and getting: lifestyles of attached and symbiotic microbes ...... 54 OS-2B. Bacterial diversity: from community composition to community functions ...... 59 SESSION 5. Giving and getting: lifestyles of attached and symbiotic microbes ...... 64 OS-6. Genomics for a better understanding of the aquatic biogeochemical processes ...... 70 OS-S1. Ecology of waterborne pathogens in the light of climate change ...... 75 OS-7. What omics can (and can't) tell us about microbial ecology ...... 82 OS-8A. Bacterial biogeography and dispersal in a changing world ...... 87 OS-9. Microbial metabolic specialization: causes and ecological consequences ...... 93 OS-8B. Bacterial biogeography and dispersal in a changing world ...... 98 OS-10. Microbial autoecology and coevolution ...... 104 OS-S2. Protists: the ecological meaning of species specific morphologies ...... 109 POSTER SESSIONS ...... 114 PS-1. Ecological consequences of global change in aquatic ecosystems ...... 114 PS-2. Bacterial diversity: from community composition to community functions ...... 156 PS-3. Phototrophic plankton as the movers and shakers in aquatic ecosystems ...... 215 PS-4. Bacterial life strategies in relation to carbon flow to higher trophic levels ...... 234 PS-5. Giving and getting: lifestyles of attached and symbiotic microbes ...... 254 PS-6. Genomics for a better understanding of the aquatic biogeochemical processes ...... 275 PS-7. What omics can (and can't) tell us about microbial ecology ...... 293 PS-8. Bacterial biogeography and dispersal in a changing world ...... 302 PS-9. Microbial metabolic specialization: causes and ecological consequences ...... 323 PS-10. Microbial autoecology and coevolution ...... 340 PS-S1. Ecology of waterborne pathogens in the light of climate change ...... 364 PS-S2. Protists: the ecological meaning of species specific morphologies ...... 384 PATRONAGES, SPONSORS AND SUPPORTERS ...... 388 AUTHOR INDEX ...... 389

3 WELCOME TO STRESA

After almost two years of hard work, we are thrilled to welcome you to the 13th Symposium on Aquatic Microbial Ecology, this year renamed 1st EMBO Conference on Aquatic Microbial Ecology: SAME13, after the very welcome support ensured by The European Molecular Biology Organization. They were two years of hard work but also unimaginable satisfaction, thanks to your incredible response and your continuous commitment that inspired and supported us in every decision. Over 400 participants, from more than 50 nations are fantastic numbers for a SAME meeting, but also a big responsibility for the organizers. For this reason, we would first acknowledge the invaluable work of the Scientific and the Local Committees: they all did their best to make SAME13 the unforgettable experience we all hope it will be.

EMBO’s sponsorship was fundamental for the successful organization of SAME13. It was flanked by the Federation of the European Microbiological Societies (FEMS), by the International Society of Microbial Ecology (ISME) and by a number of scientific Italian associations that ensured the possibility to offer grants to 35% of the over 200 students participating in SAME13 from all over the world. Moreover, thanks to the help of a number of private local companies, we will be able to offer you several extra scientific events introducing the Italian culture, history and landscapes, always with the highest respect of the environment.

The administrative work made by the Microb&co Association was fundamental for the organization of SAME13. We would like to thank all the boys and the girls of Microb&co that devoted so much time to solve all your, and our, administrative problems in incredibly fast time.

The recognition of SAME13 as an important scientific event by Mr. Giorgio Napolitano, the President of the Italian Republic, makes us proud and confirms the strategic role that aquatic microbial ecology will play in future scenarios. This is indeed strengthened by the quality of your abstracts. Twenty years of impressive improvement of technology and new discoveries make this exciting time the time of microbial ecology, and SAME13 is just surfing on the top of the wave. The selection for the few oral slots in the Plenary Session that makes SAME unique was never so hard, and painful. The Poster Sessions will never be as interesting as at SAME13.

This booklet is designed to assist you during SAME13. It includes the daily program, a map of the conference venue, the town of Stresa and its beautiful surroundings, the descriptions of the facultative excursions and of the social events. For specific questions just ask at the Reception Desk of the Congress Palace, or look around for the members of the SAME13 Staff.

We hope that SAME13 will help you to gain new insights, friendships, and memories to get you energized and inspired about your future research in the fantastic field of aquatic microbial ecology!

Once again, thank you for joining us!

Gianluca Corno Gian Marco Luna Manuela Coci Stefano Amalfitano

4 SAME13 COMMITTEES

CHAIRS Gianluca Corno (chair), CNR-ISE Verbania - Italy Stefano Amalfitano (co-chair), CNR-IRSA Rome - Italy Manuela Coci (co-chair), CNR-ISE Verbania - Italy Gian Marco Luna (co-chair), CNR-ISMAR Venice - Italy

SCIENTIFIC COMMITTEE Linda Amaral Zettler, Marine Biological Laboratory Woods Hole - USA Stefan Bertilsson, University of Uppsala - Sweden Judith Blom, University of Zurich - Switzerland Angus Buckling, University of Exeter - UK Cristiana Callieri, CNR-ISE Verbania - Italy Roberto Danovaro, Polytechnic University of Marche - Italy Nicole Dubilier, Max Planck Institute for Marine Bremen - Germany Paul A. del Giorgio, University of Quebec - Canada Carlos M. Duarte, Mediterranean Inst. for Adv. Studies Mallorca - Spain Serena Fonda Umani, University of Trieste - Italy Samantha Forde, University of California Santa Cruz - USA Gerhard Herndl, University of Vienna - Austria Klaus Jürgens, Leibniz Inst. for Baltic Sea Res. Warnemünde - Germany Rachel Noble, UNC Chapel Hill - USA John H. Paul, University of South Florida - USA Carlos Pedrós-Alió, CSIC-ICM Barcelona - Spain Thomas Posch, University of Zurich - Switzerland Fereidoun Rassoulzadegan, LO Villefranche sur Mer - France David Scanlan, University of Warwick - UK Karel Šimek, Institute of České Bud. - Czech Republic Meinhard Simon, ICBM University of Oldenburg - Germany Michael Wagner, University of Vienna - Austria

LOCAL COMMITTEE Luigi Michaud (co-organizer), University of Messina - Italy Ester Eckert, University of Zurich - Switzerland Dario Manca, CNR-ISE Verbania - Italy Alessandra Pugnetti, CNR-ISMAR Venice - Italy Roberto Bertoni, CNR-ISE Verbania - Italy Luigi Vezzulli, University of Genoa - Italy Laura Puppieni, CNR-ISE Verbania - Italy Francesco Rusconi-Clerici, Slow Food Lago Maggiore & Verbano - Italy Stefano Fazi, CNR-IRSA Rome - Italy Martino Bertoni, Biozentrum Basel - Switzerland Mario Contesini, CNR-ISE Verbania - Italy Michela Rogora, CNR-ISE Verbania - Italy Diego Fontaneto, CNR-ISE Verbania - Italy Marco Giardina, University of Catania - Italy Sonia Plechuk, University of Catania – Italy

5 GENERAL INFORMATION Symposium Venue Stresa Congress Centre Piazzale Europa 3 - 28838 Stresa Italy Phone +39 0323 30389 Fax +39 0323 33281 e-mail: [email protected] Website: http://www.stresacongressi.it/english/index.html

Name Badges All participants, accompanying persons and exhibitors are kindly requested to wear their badges throughout the symposium in order to be admitted to the session rooms and other scheduled activities.

Registration The Registration Desk at the Congress Centre will be open as follows: Sunday 8 September 14:00 - 18:00 Monday 9 September 08:30 - 16:00 Tuesday 10 September 08:30 - 16:00 Wednesday 11 September Closed Thursday 12 September 08:30 - 16:00 Friday 13 September 08:30 - 13:00 (lunch break every day 13:00 - 14:00)

Internet An internet and printing service is located in the SAME13 Registration desk. Wi-fi connection is ensured by Eduroam and SAME13 in the plenary room, in the foyer, and in the poster rooms. Login and password can be found in the SAME13 Bag.

Refreshments Organic and zero-km refreshments will be served during the coffee breaks in the exhibition and poster area. SAME13 Menabrea Special Edition beers will be offered during the Poster&Beer Sessions. Lunches are not included in the registration fee.

Liability and Insurance The organizer is not able to take any responsibility whatsoever for injury or damage involving persons and property during SAME13. Participants are advised to take out their own personal travel and health insurance for their trip.

Disclaimer This program book was made with the greatest care and based on the info available at the time; however, this does not imply that it is completely without flaws or inconsistencies. We apologize for any inconvenience caused by this.

6 DESTINATION STRESA

For however fanciful and fantastic the Isola Bella may be, and is, it still is beautiful (C. Dickens, 1844)

Charles Dickens was only one of many famous people who enjoyed some time spent in Stresa along hystory. Also, Stendhal and Flaubert were commonly walking on Stresa's beach, and Ernest Hemingway wrote his masterpiece A Farewell to Arms here. Lord Byron as well as an infinite list of European kings and queens chose Stresa as halting place during their Grstresa conferenceand Tours. Stresa hosted a number of international conferences, from the unsuccessfull meeting between Italy, France and United Kingdom in 1935, when the European countries had to face Hitler's machinated assassination of the Austrian Cancellor Dolfuss, to the European Community Conference in 1958 when the first common laws for agricultural development and a common agricultural policy were signed between European States. But Stresa's hystory is much older. Its first appearance on historical documents was just before the end of the first millennium, when it was a small community of fishermen and peasants. From the Renaissance, the Borromeo family, part of the Milanese aristocracy, ruled the region and added the magnificent buildings that have made Stresa famous. Throughout the 16th and 17th centuries, the Borromeos commissioned palaces to be built on the islands Bella and Madre. Stresa passed into Austrian hands in 1719, before isola bellacoming under the rule of the House of Savoy in 1748, unified in the Italian Kingdom in 1861. The town began to achieve its renown as a tourist destination at the beginning of the 19th century, when glamorous villas were built by Italian and European noble families. In 1906 the opening of the Simplon Tunnel heralded the start of widespread international travel. Trains on the London-Paris-Milan line began to call at Stresa station, and travellers and writers from all over Europe came to sing the praises of Stresa and Lake Maggiore, spreading their fame far and wide and enticing an ever larger number of people to visit. From Stresa it is easy to reach the three Borromean Islands, which are steeped in artistic, historical and botanical appeal. On the islands of Bella and Madre there are sumptuous palaces and rare plant gardens where peacocks, parrots and pheasis pescatoriants roam wild against an exotic backdrop reminiscent of faraway lands. In contrast, the Isola dei Pescatori is famous for the charming simplicity of its old fishing village, which is considered one of the most picturesque spots on Lake Maggiore. As well as being a fine example of a mid-nineteenth century palace, Villa Pallavicino boasts a zoo in its huge park. In Stresa itself, the elegant and attractive waterfront offers unforgettable views of the Gulf of Borromeo. Walks along the shore offer the perfect opportunity to take in both the Art Nouveau hotels on the shore and the three Borromean Islands. The view is equally superb from the summit of Mount Mottarone (1491m), which dominates Stresa and offers a unique panoramic outlook. The appeal of Lake Maggiore is not confined to Stresa; in fact, the town is the perfect starting point for unforgettable boat trips on the lake or drives along its shores. Close by to the north is the tranquil tourist town of Verbania-Pallanza. Its main attraction, Villa Taranto, is world-famous for its magnificent gardens of rare flosancarlonewers and plants. Further up the shores of the lake lies the village of Cannero Riviera, which enjoys a sheltered location and consequently a particularly mild climate in which lemons and oranges can be grown. There is a series of evocative fortifications on the three Castelli di Cannero islets, which form a small archipelago opposite the village. From here, it is also only a short distance to Cannobio - the last Italian town before the Swiss border. This beautiful and ancient little town, nestled between the mountains and the lake, today has one of the most beautiful lidos on the lake. To the south lies the tourist and commercial hub of Arona. The copper statue dedicated to the town's patron saint, Charles Borromeo, is among the tallest in Europe at 35 m. Opposite Arona, on a rocky outcrop on the eastern shore of Lake Maggiore, sits the Rocca d'Angera, a fully preserved medieval fortress that houses the original Doll and Toy Museum. St. Catherine's Hermitage clings precariously to sheer cliffs on the opposite shore to Stresa, above one of the deepest areas of Lake Maggiore.

7 SOCIAL EVENTS

OPENING CEREMONY AND WELCOME APERITIF SULLE NOTE DEL LAGO Sunday 8 September 2013, 16:00 - 20:00 Venue: Stresa Congress Palace Dress: Casual The event is included in the registration fee. Join us for the SAME13 opening ceremony in the Plenary Hall of the Stresa Congress Palace! The program will feature a welcome and a short historic introduction to SAME and to SAME13, as well as the presentation of the microbial ecology research on the shores of Lake Maggiore in the last 75 years (since the establishment of the Italian Institute of Hydrobiology in Verbania, today named CNR-ISE) by Gianluca Corno. Following this, the first two exciting Opening Lectures will be presented by Farooq Azam (Scripps Institution of Oceanography University of California, San Diego, USA) and Sinead Collins (University of Edinburgh, UK). As the trip to Stresa and the lectures could have make you hungry, you are invited to join all SAME13 convenors for a fun evening with music, drinks and snacks in the Lake Room of the Congress Palace. Tasting local organic dishes, Piedmontese wines and refreshing SAME13 Menabrea beers you will be seduced by the sound of the best Italian jazz by the Ragazzi Scimmia del Jazz band. This is a perfect way to catch up with colleagues and a chance to meet new ones.

SAME13 DINNER AT THE VILLA AND PARTY Thursday 12 September 2013, 19:00 - 1:30 Venue: Villa Rusconi-Clerici, Verbania Dress: Casual The event is included in the registration fee for students and confirmed for the first 275 registered convenors. The not-to-be-missed SAME Fest, this year is hosted at the glamorous Villa Rusconi- Clerici, an historical location on the shore of Verbania, just on the opposite side to the Borromean Gulf. Convenors will reach the private pier of the Villa by taxi boats, leaving Stresa around 18:00. The dinner, overlooked by the Lake Maggiore and Verbano Convivium of Slow Food, will guide them through local products in a friendly environment in the art deco Pavillon of the Villa. Stunning local wines from Rovellotti wine makers, SAME13 Menabrea beer and local mineral waters from Bognanco will accompany the the food. Mr. Rusconi-Clerici will introduce the history of the Villa, and Rovellotti sommelliers will guide the convenors through a surprising wine tasting. After the dinner we will move to the cellars of the Villa where a super funny trip through pop and dance music from the 50s to the last summer will be performed by the Timetravel Music Band. A cocktail bar will be organized and drinks will be available (this service is not included in the invitation ticket). During the whole evening, there will be taxi boats ready to bring back convenors to Stresa, upon request.

8 MID-SAME OPTIONAL EXCURSIONS

In keeping on the SAME tradition, no scientific session are scheduled on the afternoon of Wednesday 11 September 2013. Participants will be free to take advantage of the many leisure opportunities in and around Stresa. A number of excursions with reduced impact on the environment and high naturalistic value have been selected, offering you an opportunity to explore the beautiful Stresa surroundings during your afternoon off. You will be asked to pay the fee at the SAME desk in Stresa. SAME13 organization is not responsible for the excursions, which are professionally organized. Two or more members of SAME13 staff will be accompanying the participants of every tour. There are limited places for each excursion, but some tours will still have tickets available. Please see the registration desk for more details.

Selected tours are:

Val Grande National Park You will have the chance to take a light trekking within the largest wilderness area in Italy, discovering the traces of the ancient civilization of the Alps. Small buses will leave Stresa to the Val Grande National Park at 13:30. Retour in Stresa is scheduled at 19:00. In case of heavy rain, the walk will be substituted by a visit to the Val Grande Educational Centre. Required: wind jacket, trekking shoes, long trousers. Excursion fee: 30 euros per person (approx.)

Mountain bike trip Mottarone-Stresa Leaving the shore of Stresa by the quiet old-fashioned cableway at about 14:00 you will reach the top of the mountain within 30 minutes. There you will find your mountain bike, as well as your helmet, waiting for you. A short briefing with your professional guides, and then down! The guides will be with you along the whole run, that is panoramic and mostly off-road. A number of pit stops, to enjoy the different views, the little villages, and the nature, are possible. The downhill is planned with different difficulty levels, in order to allow also the less sporty of us to enjoy the trip. Back to Stresa around 18:00. In case of heavy rain, the tour will be cancelled. Required: sporty clothes, sunglasses, and sunscreen. Excursion fee: 50 euros per person (approx.)

Borromean Islands Leaving Stresa’s harbour by ferry at 14:00 in a few minutes you will reach the world famous Isola Bella where you will visit the incredible Borromeo Palace and its gardens explained by professional guides. A second ferry will then take you to the Isola dei Pescatori, where you will have time to visit, with the guide or alone, the picturesque fisherman village, or to enjoy a drink at the beach. The ferry will take you back to Stresa around 18:30. Required: sunglasses, sunscreen. Excursion fee: 40 euros per person (approx.)

Snorkeling at Lake Megozzo What is better than a relaxing afternoon in the middle of the meeting? Lake Mergozzo is a deep, clear oligotrophic lake, where tourism and leisure are the only activities allowed. We will leave Stresa by train at 14:00 and, within twenty minutes, we will be at the Rustica beach, on the southern side of Lake Mergozzo. The grass beach is large, surrounded by a wood and a few cane

9 thickets. The access to the lake is very easy, through a large inlet of soft white sand (max depth 40 cm). The water reaches two metres at about 50 m from the shore, allowing relaxing baths in safe waters. We will have a 500 m long snorkeling trip from the beach to the eastern coast of the lake, were a vertical cliff (artificial for the first 120 m, then natural) is forming a natural habitat for many species of fishes. The afternoon at the beach will include also a snack with a typical piadina and a real chinotto (a soft drink made up from the fruit Citrus myrtifolia). We plan to take the train back to Stresa at 18:30. The excursion will end before 19:00. In case of heavy rain, the tour will be cancelled. Required: bathing suit, sunglasses, sunscreen, beach towel, mask & snorkel (fins can help but are not necessary). Excursion fee: 15 euros per person (approx.)

Villa Taranto and the Institute of Ecosystem Study The excursion will start around 14:00 from the harbour of Stresa, where participants will take a ferry and cross Lago Maggiore, directly reaching the botanical garden of Villa Taranto in Verbania, one of the largest and richest in Europe. After the visit and a refreshing break at the lake, we will then take a 20 minutes’ walk around Verbania’s Cape to reach the Institute of Ecosystem Study (CNR-ISE) where some researchers will introduce you to the historical villa and the labs in the year of the 75th anniversary of the Institute's foundation. The Institute, based in a wonderful 19th century villa directly on the waterfront of Verbania- Pallanza, is the continuation of the formerly Italian Institute for Hydrobiology, founded in 1938, to study the biology of freshwater organisms, the physics and the chemistry of inland waters. It is one of the oldest limnological stations across Europe, and hosted the most famous researchers in the different fields of aquatic studies. The villa was donated to the State by Dr. Marco de Marchi (a well known naturalist from Milan). Along 75 years of history, the Italian Institute of Hydrobiology faced the fascism, then World War II, the post-war reconstruction, the economic boom of the ‘60s, the crisis of the ‘70s (that resulted in its incorporation within the CNR), up to the new challenges of the third millennium. Nowadays about 40 people, including researchers, technical and administrative staff, are dealing with studies on basic and applied research in freshwater ecology and , working on unsolved problems from antrophization to climate change, from ecological theory to studies on atmospheric depositions. Moreover the Institute publishes a well know independent scientific magazine (the Journal of Limnology, follow-up of the historical series of the Memorie). From the Institute we will then take the ferry back to Stresa, where we will arrive around 19:00. In case of heavy rain, the tour can be modified. Required: a good camera with excellent macro function. Excursion fee: 30 euros per person (approx.)

For more information, please visit the SAME13 website, or visit the registration desk of Stresa Congress Palace.

10 INFORMATION FOR PRESENTERS

Language The official language of SAME13 is English.

Oral Presenters Length of Presentations: each contributed session presentation will be 15 minutes in length including time for questions. Speakers in invited sessions are allocated 30 minutes including question time. Session Chairpersons: please, refer to the Program Book you will receive at the Conference for name of your session’s Chairperson(s). Please meet your Chairperson in your session room 15 minutes prior to the start of your session. Presentation Upload: if you are using a PowerPoint or other electronic presentation, it must be uploaded onto the conference computers preferable the day before or at least 2 hours prior your presentation. Speaker ready staff will be available at the Reception Desk of the Congress Palace during every session. Audio Visual Information: it is strongly encouraged for you to bring your presentation on a number of formats and you are discouraged from using your own laptop. The use of PowerPoint presentations is strongly encouraged. The Organizing Committee will provide Computer with Microsoft Office, Data Video Projector and Screen, Lectern and Microphone, Laser Pointer.

Poster Presenters The Poster&Beer Sessions are scheduled on Monday, Tuesday and Thursday late afternoon according to the topics of the day(s). All posters will stand for the whole Symposium duration in the foyer of the Congress Palace. Please, check the poster number and assigned session in the program. The first presenting Authors are requested to be available for questions of your poster during the scheduled poster sessions and to ensure that the poster is removed before the conclusion of the Conference. The event coordinators will dispose those not removed by that time. For best results, please prepare your poster as portrait (ideal: 841 mm width x 1189 mm height; DIN A0; maximum 900 mm width x 1200 mm height). The posters are fixed on stands and cannot be rotated. Mounting supplies are provided by the site. Did we print your poster? Your will find it already standing on its place, waiting for you (FCS paper produced by sustainable forestry).

SAME13 BEST PRESENTATION PRIZES

SAME13 recognition and monetary awards (consisting in € 250 each) will be given to the most outstanding two posters and two talks presented by students at the SAME13. Presentations will be judged by the members of the SAME13 Scientific Committee based on innovation, scientific insight, quality of experimental design and methods, clarity and effectiveness of presentation. There is no need to apply; all student presentations will be judged and taken into consideration for the awards. The Awards Ceremony will take place on Friday 13th late morning, after the Closing Lecture.

11 KEYNOTE SPEAKERS

SUNDAY 8 SEPTEMBER 2013, 16:30 Farooq Azam Scripps Institution of Oceanography, University of California - San Diego (USA) Farooq studies marine microbial biogeochemistry. He and his students and postdocs have been contributing to the mechanistic understanding of microscale interactions of pelagic microbes with the ocean and their consequences for large scale ecosystem functioning and response to system stress.

SUNDAY 8 SEPTEMBER 2013, 17:30 Sinead Collins School of Biological Sciences, University of Edinburgh (UK) Sinead’s main area of research is how adaptive evolution occurs over hundreds or thousands of generations in large populations, where complex ecology or genetics have to be taken into account. She uses experimental evolution in microbes, and applies her work to understanding long- term responses of to (complex) global change.

MONDAY 9 SEPTEMBER 2013, 09:00 Toshi Nagata Atmosphere and Ocean Research Institute, University of Tokyo (Japan) Toshi current study focuses on organic matter-microbe interactions and the role of , and protists in the regulation of material cycling in marine environments. In order to achieve the research goal, he uses microbiological, molecular, biogeochemical and isotopic approaches. He also collaborates with theoreticians and modelers to explore fundamental features in functions across scales.

MONDAY 9 SEPTEMBER 2013, 14:00 Dagmar Wöbken NanoSIMS Group - Department of Microbial Ecology, University of Vienna (Austria) Dagmar joined the Department of Microbial Ecology at the University of Vienna as a group leader in early 2012. Her research group investigates active participants in the N and C cycle across terrestrial and aquatic ecosystems using a wide array of methods, but focusing on stable isotope probing, NanoSIMS and single cell techniques.

TUESDAY 10 SEPTEMBER 2013, 09:00 Jakob Pernthaler Limnological Station, University of Zurich (Switzerland) Jakob investigates the role and fate of different bacteria in freshwater and in the context of food web structure and substrate availability. He studies the effects of predator-induced mortality on the composition of microbial assemblages, and in the potential adaptations of microbial species to compensate or to avoid such losses.

12 TUESDAY 10 SEPTEMBER 2013, 11:15 Rachel Foster Department of Biogeochemistry, Max Planck Institute for Marine Microbiology - Bremen (Germany) Rachel’s primary research focuses on the distribution, activity and diversity of marine and their overall roles in ecosystem function. More specifically, she focuses on open ocean phytoplankton populations important to Nitrogen and Carbon cycling, with a strong emphasis on planktonic symbioses.

TUESDAY 10 SEPTEMBER 2013, 14:00 Roberto Danovaro Department of Life and Environmental Science - DISVA, Polytechnic University of Marche (Italy) Roberto’s research is focused on deep-sea biodiversity and ecology with a synecologic and interdisciplinary approach dedicated to the identification of the links between ecosystem functioning and the production of goods and services.

WEDNESDAY 11 SEPTEMBER 2013, 09:00 Mary Ann Moran Department of Marine Sciences, University of Georgia (USA) Mary Ann research program focuses on the genetic basis of bacterial sulfur and carbon cycling in the ocean, with the goal of understanding the role of marine bacteria in the of the coastal ocean and the formation and flux of climatically active gases. Her research uses molecular microbial ecology and ecological genomics approaches to explore bacterial processes and their regulation in seawater.

THURSDAY 12 SEPTEMBER 2013, 11:15 Josep M. Gasol Aquatic Microbial Ecology Group, CSIC Institute of Marine Sciences - Barcelona (Spain) Pep was jealous of the physical oceanographers that came to cruises with just a bunch of CDs to record the data and didn’t do practically any wet work, and when he discovered a machine called flow cytometer, he decided it was as similar as possible to the physicists work so he decided to learn about it and try to push its limits for work with microbes. Now that he thinks of it, maybe this is also the reason why he is lately interested in high-throughput sequencing. Stop being wet…

THURSDAY 12 SEPTEMBER 2013, 14:00 Jay Lennon Department of Biology - Indiana University (USA) Jay’s laboratory focusses on the biotic and abiotic factors that generate and maintain microbial biodiversity. In turn, they seek to understand the implications of microbial diversity for ecosystem functioning.

FRIDAY 13 SEPTEMBER 2013, 09:00 Christopher Marx Department of Organismic and Evolutionary Biology - FAS Center for Systems Biology, Harvard University (USA) Christopher’s broad research goal is to develop a degree of predictability to future evolutionary trajectories or ecological states based upon the internal physiological function of the organisms present.

13 FRIDAY 13 SEPTEMBER 2013, 12:15 Roman Stocker Department of Civil and Environmental Engineering, Massachusetts Institute of Technology (USA) Leveraging his quantitative background in engineering and applied mathematics, Stocker has pioneered the use of microfluidics in microbial oceanography. By using microfluidics to generate carefully controlled nutrient landscapes and flow conditions, Stocker’s research has addressed a long-standing challenge in microbial oceanography: to study marine microbes in the context of their immediate microenvironment.

14 CONFERENCE VENUE

15 SAME13 GENERAL PROGRAM

SUNDAY 8 SEPTEMBER 2013

TIME EVENT

12:30 SAME13 Registration open

15:45 SAME13 Welcome by Gianluca Corno

Opening Lecture by Farooq Azam 16:30 Microbial structuring of : from molecular interactions to global ecosystem connectivity

Opening Lecture by Sinead Collins 17:30 Plastic fantastic

18:30 SAME13 Welcome Aperitif Sulle note del Lago

16 MONDAY 9 SEPTEMBER 2013

TIME EVENT Invited Lecture by Toshi Nagata 9:00 Embedding microbial foodwebs into ocean biogeochemical models: challenges towards a global synthesis SESSION 1. Ecological consequences of global change in aquatic ecosystems Chairs: Klaus Jürgens and Mauro Celussi 9:30 Ruben Sommaruga 9:45 Eeva Eronen-Rasimus 10:00 Anna M. Romaní 10:15 Daniel Herlemann 10:30 Gordon Taylor 10:45 COFFEE BREAK SESSION 2. Bacterial diversity: from community composition to community functions Chairs: Stefan Bertilsson and Carina Rofner 11:15 Imma Noguerola 11:30 Pierre Galand 11:45 Andrea Franzetti 12:00 Marc Mussmann 12:15 Lucia Bongiorni 12:30 Paul del Giorgio 12:45 LUNCH BREAK Invited Lecture by Dagmar Wöbken 14:00 N2 fixation in coastal microbial mats: from the process level to single cells SESSION 3. Phototrophic plankton as the movers and shakers in aquatic ecosystems Chairs: Alessandra Giani and Marie-Eve Garneau 14:30 Verena Brauer 14:45 Cristiana Callieri 15:00 Jarone Pinhassi 15:15 Marc Llirós 15:30 Manuela Hartmann 15:45 COFFEE BREAK SESSION 1. Ecological consequences of global change in aquatic ecosystems Chairs: Gordon Taylor and Beatriz Modenutti 16:15 Beatriz Modenutti 16:30 Federico Baltar 16:45 Jatta Karhunen 17:00 Cecilia Alonso 17:15 Hannes Peter

17:30 POSTER&BEER SESSIONS 1-3-4-7

17 TUESDAY 10 SEPTEMBER 2013

TIME EVENT Invited Lecture by Jakob Pernthaler 9:00 Opening Pandora’s Black Boxes: what have they done to our “active” bacteria? SESSION 4. Bacterial life strategies in relation to carbon flow to higher trophic levels Chairs: Gerhard Herndl and Michaela Salcher 9:30 Karoline Wagner 9:45 Karel Simek 10:00 Jesús M. Arrieta 10:15 Sarahi L. Garcia 10:30 Michaela Salcher 10:45 COFFEE BREAK Invited Lecture by Rachel Foster 11:15 A symbiotic advantage: diatoms and work together to make the most in a nitrogen deplete ocean SESSION 5. Giving and getting: lifestyles of attached and symbiotic microbes Chairs: Jarone Pinhassi and Ilaria Pizzetti 11:45 Ilana Berman 12:00 Pedro Frade 12:15 Sebastian Dirren 12:30 Pre-Lunch Talk by Stefan Bertilsson (Frontiers and PLoS) 12:40 LUNCH BREAK Invited Lecture by Roberto Danovaro 14:00 New insights on the diversity of and their impact of on the functioning of the global biosphere SESSION 2. Bacterial diversity: from community composition to community functions Chairs: Cecilia Balestra and Isabelle Biegala 14:30 Alexander Eiler 14:45 Danny Ionescu 15:00 Kenji Kato 15:15 Helmut Buergmann 15:30 Martina Herrmann 15:45 COFFEE BREAK SESSION 5. Giving and getting: lifestyles of attached and symbiotic microbes Chairs: Nicole Dubilier and Jessica Tout 16:15 Nicole Dubilier 16:30 Ester Eckert 16:45 Ottavio Croze 17:00 Melissa Garren 17:15 Jessica Tout

17:30 POSTER&BEER SESSIONS 2-5-6

18 WEDNESDAY 11 SEPTEMBER 2013

TIME EVENT Invited Lecture by Mary Ann Moran 9:00 Metatranscriptomic probing of microzones and interfaces SESSION 6. Genomics for a better understanding of the aquatic biogeochemical processes Chairs: Rodolfo Paranhos and Andrea Fuchs 9:30 Meinhard Simon 9:45 Anne Steenbergh 10:00 Rodolfo Paranhos 10:15 Erin Field 10:30 Brandon Satinsky 10:45 COFFEE BREAK SPECIAL SESSION S1 – Ecology of waterborne pathogens in the light of climate change Chairs: Ingrid Brettar and Luigi Vezzulli 11:15 K. Mathias Wegner 11:30 Johanna Thelaus 11:45 René Lesnik 12:00 Aurélie Touron-Bodilis 12:15 Lorenzo Righetto 12:30 Pre-Lunch Talk by Daniele Daffonchio (FEMS) 12:40 LUNCH BREAK

14:00 SAME13 Excursions

19 THURSDAY 12 SEPTEMBER 2013

TIME EVENT 9:00 Invited Lecture by Josep M. Gasol Patterns of microbe abundance and diversity in the deep ocean: the circumnavigation cruise Malaspina2010 SESSION 7. What omics can (and can't) tell us about microbial ecology Chairs: Manuel Martinez-Garcia and Anders Andersson 9:30 Daniel Lundin 9:45 Brandon Swan 10:00 Emilio O. Casamayor 10:15 Sara Beier 10:30 Stefan Bertilsson 10:45 COFFEE BREAK SESSION 8. Bacterial biogeography and dispersal in a changing world Chairs: Stefano Fazi and Craig Plante 11:15 Alexander H. Frank 11:30 Johanna Sjöstedt 11:45 Andrea Butturini 12:00 Gavin Lear 12:15 China Hanson 12:40 LUNCH BREAK Invited Lecture by Jay Lennon 14:00 Microbial seed banks: ecological and evolutionary implications of dormancy SESSION 9. Microbial metabolic specialization: causes and ecological consequences Chairs: Cecilia Alonso and Karel Hornak 14:30 Tanja Shabarova 14:45 Jacqueline Rochow 15:00 Sanjay Swarup 15:15 Linda Wilhelm 15:30 Frank Schreiber 15:45 COFFEE BREAK SESSION 8. Bacterial biogeography and dispersal in a changing world Chairs: Eva Sintes and Diego Fontaneto 16:15 Eva Sintes 16:30 Eva Mayol 16:45 Anna J. Székely 17:00 Rebecca Störmer 17:15 Jean-François Ghiglione

17:30 POSTER&BEER SESSIONS 8-9-10-S1-S2

SAME13 19:15 Dinner at the Villa and Party

20 FRIDAY 13 SEPTEMBER 2013

TIME EVENT Invited Lecture by Christopher Marx 9:00 Growth of multi-species communities in time and space: predictions from genome-scale models SESSION 10. Microbial autoecology and coevolution Chairs: Jessica Labonté and Antonio Dell’Anno 9:30 Christian Winter 9:45 Jessica Labonté 10:00 Jens Glaeser 10:15 Martin Hahn 10:30 Carlo Berg 10:45 COFFEE BREAK SPECIAL SESSION S2. Protists: the ecological meaning of species specific morphologies Chairs: Thomas Posch and Pierangelo Luporini 11:15 Jim Mitchell 11:30 Stina Israelsson 11:45 Luciana Santoferrara 12:00 Thomas Posch Closing Lecture by Roman Stocker 12:15 Keep looking: the power of direct observation in microbial ecology

12:45 SAME13 Final remarks by Gerhard Herndl and closing ceremony

21 ORAL PLENARY SESSIONS

SUNDAY 8 SEPTEMBER 2013

16:30 MICROBIAL STRUCTURING OF OCEANIC CARBON CYCLE: FROM MOLECULAR INTERACTIONS TO GLOBAL ECOSYSTEM CONNECTIVITY

Invited opening lecture by Farooq Azam Scripps Institution of Oceanography, University of California - San Diego (USA)

Discoveries during the last several decades have shown that microbes play major roles in global ocean carbon cycle, and genomic and related approaches have been uncovering an incredible wealth of microbial diversity and potential for biochemical expression. Despite these huge advances we cannot yet predict how ecosystem perturbation (e.g. climate change, ocean fertilization, , overfishing, or oil spills) will affect the role microbes play in structuring the carbon cycle of the future ocean. In order to meet this challenge we must understand the underlying regulatory mechanisms of system function and resilience and explicitly appreciate the importance of in situ biology of the microbes. Complexity and habitat scale are major challenges in microbial ecology and I will discuss some recent and novel conceptual and methodological approaches. The role of nanoscale to microscale interactions of microbes in ecosystem structuring would benefit from converging next-gen -omics with “next-gen imaging” of biogeochemical dynamics. I will discuss the hypothesis that microbial communities are a major structuring force for ecosystem connectivity and resilience through cumulatively diverse metabolic interactions with the organic matter continuum. Such molecular-level integrative and mechanistic view that explicitly considers the microbe’s habitat can help formulate new hypotheses and models to better predict future ocean biogeochemical variability and response to climate change. It may also contribute to the development of a “new microbial ecology”.

22 SUNDAY 8 SEPTEMBER 2013

17:15 PLASTIC FANTASTIC

Invited opening lecture by Sinead Collins School of Biological Sciences, University of Edinburgh (UK)

Marine microbes are the small but mighty foundations of marine ecosystems, the tiny drivers of nutrient cycles, and fascinating in their own right. As the ocean changes, they have the capacity to evolve because of their large population sizes and short generation times, but most studies measure physiological responses of phytoplankton to . Can we use this data to learn how future microbial communities will differ from contemporary ones? What do plastic and epigenetic responses tell us about microevolution? I will show what adaptive plastic responses tell us about evolutionary responses in the globally-distributed Ostreococcus tauri, and how this is relevant to understanding marine microbial responses to global change. I will also discuss the (many) challenges and benefits of using marine microbes for the nefarious purposes of “hardcore” experimental evolution, and the current explosion of “softcore” microbial experimental evolution studies using marine phytoplankton.

23 MONDAY 9 SEPTEMBER 2013

9:00 EMBEDDING MICROBIAL FOOD WEBS INTO OCEAN BIOGEOCHEMICAL MODELS: CHALLENGES TOWARDS A GLOBAL SYNTHESIS

Invited lecture by Toshi Nagata Atmosphere and Ocean Research Institute, University of Tokyo (Japan)

During the past three decades, studies have demonstrated that the processing (transformation and degradation) of organic matter (OM) by microbial food webs consisting of bacteria, protists and viruses plays a major role in the regulation of biogeochemical cycles in the oceans. However, there have been surprisingly few studies that have explicitly incorporated - OM interactions into global biogeochemical models. The present talk introduces the results of our study using a global three-dimensional numerical model of the ocean general circulation and biogeochemistry to evaluate how microbial processes and OM interact with each other and affect global marine biogeochemical cycles and productivity. The initial analysis of this model, including the results of sensitivity analyses, is then used as a basis for identifying the major gaps in our knowledge regarding the key microbial processes. Finally, I discuss how complex microbial interactions could be effectively embedded into the global models in order to improve our ability to predict responses of ocean biogeochemical cycles and ecosystems to global change.

24 MONDAY 9 SEPTEMBER 2013 OS-1A. Ecological consequences of global change in aquatic ecosystems

9:30 ARE HETEROTROPHIC NANOFLAGELLATES MISSING IN GLACIER-FED LAKES?

Ruben Sommaruga, University of Innsbruck, Lake and Glacier Ecology Research Group (Austria) Coauthors: Kandol G

The food-web structure of glacier-fed lakes is little known, yet this type of lake was at the origin of many freshwater ecosystems worldwide and the current rapid retreat of glaciers is creating many new ones. In a previous study of lakes with different glacier influence, we observed that planktonic heterotrophic nanoflagellates were apparently absent above a given turbidity threshold. To understand this pattern, we tested the effect of ‘glacial flour’ turbidity on the growth of flagellate species, as well as on a natural flagellate assemblage from a clear alpine lake. The glacial particles were also analyzed for its mineralogy, organic content, and grain size distribution. The presence of glacial flour reduced the growth of Spumella sp. even at the lowest turbidity tested. The negative effect was concentration dependent and it was not caused by physical damage, but rather by the interference of the particles with grazing as assessed in experiments with fluorescently labelled bacteria. Cell abundance of the natural flagellate community also significantly decreased in the presence of glacial particles and this effect was strongest at the highest turbidity tested (30 NTU). Our results indicate that the high glacial turbidity negatively affects the survival of heterotrophic flagellates and probably hinders the colonization of very turbid glacial lakes by this key group of organisms. Their absence should have important consequences for the structure and production of the prokaryotic community.

25 MONDAY 9 SEPTEMBER 2013 OS-1A. Ecological consequences of global change in aquatic ecosystems

9:45 BACTERIAL COMMUNITY DYNAMICS AND ACTIVITY DURING SEA ICE FORMATION IN A MESOCOSM EXPERIMENT: RELATIONSHIPS WITH DISSOLVED ORGANIC MATTER AVAILABILITY

Eeva Eronen-Rasimus, Finnish Environment Institute, Marine Research Centre (Finland) Coauthors: Kaartokallio H, Lyra C, Autio R, Kuosa H, Dieckmann G, Thomas D

When sea ice forms, dissolved organic and inorganic components in the parent seawater are concentrated into brine channels and pores in which diverse assemblages of micro-organisms are found. The main bacterial groups found in sea ice are from the phylum Bacteroidetes (e.g. class Flavobacteria), α- and γ- proteobacteria classes but also β-proteobacteria, gram positive bacteria and are found. There is evidence that the nutrient regime of the parent water could influence on bacterial communities during ice formation. The aim of the experiment was to study development of bacterial communities as sea ice forms, and to evaluate the effect of the parent seawater DOM content on it. Additionally we wanted to find out whether the sea ice bacterial community, formed during freezing, reflected the seawater bacterial community, or whether selective enrichment between phylotypes occurred. Bacterial communities in sea ice (top-, middle- and bottom ice), under ice water, brine and frost flowers were studied experimentally in replicate 1m3 mesocosms, using unfiltered seawater from the North Sea. The effect of DOM enrichment was investigated in parallel set of mesocosms using a microalgal derived DOM addition to North Sea water. Terminal restriction fragment length polymorphism (T-RFLP) and cloning were used to together with bacterial production measurements to investigate the bacterial communities. Active sea ice bacterial communities, that consisted typical sea-ice associated bacteria, developed in both natural and DOM-enriched conditions. In general, sea-ice bacterial communities reflected those in initial seawater but also bacterial species, not detected in initial seawater samples, were found. In DOM-enriched mesocosms γ-proteobacteria dominated in all sample types throughout the experiment, except in the initial seawater samples. Un-manipulated mesocosms where dominated by α-proteobacteria and Flavobacteria with only a brief dominance of γ-proteobacteria in the top ice in the beginning of the experiment. The results indicate that development of the sea ice bacterial communities was strongly controlled by the DOM status of the water. Also, DOM addition led to higher bacterial production rates. Dominance of the γ-proteobacteria in a DOM- enriched mesocosms indicate that γ-proteobacteria have a potential for opportunistic growth in sea ice.

26 MONDAY 9 SEPTEMBER 2013 OS-1A. Ecological consequences of global change in aquatic ecosystems

10:00 DIFFERENTIAL SENSITIVITY OF MICROORGANISMS TO TEMPERATURE: INTERACTIVE AND FUNCTIONAL CONSEQUENCES

Anna M. Romaní, Institute of Aquatic Ecology, University of Girona (Spain) Coauthors: Freixa A, Perujo N, Ylla I

The different microorganisms composing a biofilm (bacteria, protozoa, algae, rotifers) may show a differential response to temperature. Since in a biofilm there is a physical proximity and usually a strong relationship between the different components, a shift in the distribution of the different microorganisms may affect their interactions and the whole biofilm metabolic outcome. In the present experiment, were developed in the laboratory at 10, 15, 20 and 25°C from the beginning of their formation and until 26 days. The colonization of bacteria, ciliate, algae and rotifers were analysed as well as the enzymatic activities of β-glucosidase and leucine- aminopeptidase. At the same time, biofilm and respiration was measured for days 12, 19 and 26. The sensitivity of algae and bacteria to temperature was similar and a temperature increase from 10-15°C up to 20-25°C determined their faster and earlier colonization but they reach similar values at the mature biofilm for all temperatures. A similar effect was observed for ciliate colonization but at the mature 25°C-biofilm ciliate density was 2.5 higher than those measured in biofilms grown at 10, 15 and 20°C. The density of rotifers was extremely high at the 25°C-biofilm with values 25 times higher than those measured at 10°C. Density of rotifers at 15 and 20°C increased later but reached similar values at the mature biofilm than those at 25°C. Grazing pressure is enhanced at higher temperatures and this might determine the similar chlorophyll values maintained for all biofilms after 26 days of colonization. Gross primary production and respiration showed much lower sensitivity to temperature (lower Q10 values) than those observed for ciliate and rotifers. Also, the heterotrophic use of peptides was non-sensitive to temperature while β-glucosidase was significantly increasing at the 20 and 25°C grown biofilms. The results suggest that the changes of protozoa and rotifers at higher temperatures are affecting the biomass development of the microbial biofilm compartments and indirectly their functioning.

27 MONDAY 9 SEPTEMBER 2013 OS-1A. Ecological consequences of global change in aquatic ecosystems

10:15 MICROBIAL DECOMPOSITION OF SUBARCTIC, RIVERINE TERRIGENOUS DISSOLVED ORGANIC MATTER AT DIFFERENT SALINITIES

Daniel Herlemann, Leibniz Institute for Baltic Sea Research, Warnemünde (Germany) Coauthors: Manecki M, Dittmar T, Jürgens K

A large amount of terrigenous dissolved organic matter (tDOM) is mobilized by melting of permafrost and reaches through the the marine environment. The bioavailability of tDOM is an important factor for the global carbon cycle but our understanding of its decomposition and bacteria-tDOM interactions is poor. In order to investigate the role of salinity and bacterial diversity on the decomposition of subarctic, riverine tDOM, we performed mesocosm experiments in three different Baltic Sea salinity regions at winter and spring conditions. Experiments performed in winter indicate a significant effect of tDOM addition on the microbial activity in the brackish (mesohaline and oligohaline) mesocosm but not in the marine mesocosm. Amplicon pyrosequencing of 16S rRNA genes revealed that the bacterial communities and their dynamics differed between marine and brackish mesocosms. The bacterial community composition differed also between manipulated and control mesocosm in the first three days of the experiment. However, after this period the difference vanished and a phylotype of the Flavobacteria became most abundant at marine and a Paraperlucidibaca-related phylotype at brackish conditions. Ultra high resolution mass spectrometry (FT-ICR-MS) analysis of DOM revealed the microbial utilization of thousands molecularly extreme diverse substrates. Despite these broad molecular changes of DOM, the bulk concentration of changed only marginally during the experiment, indicating that the complete oxidation of DOM into CO2 was minor. However, similar decomposition processes occurred in manipulated and control mesocosms, suggesting that native DOM is utilized. The FT-ICR-MS analysis also demonstrated that the native tDOM concentration naturally decreases from oligohaline to marine conditions in the mesocosm. The addition of tDOM therefore changed the native DOM composition in the marine mesocosms more than in the brackish mesocosms. The relatively small change in native DOM composition by tDOM addition in the oligohaline mesocosm may explain the increased bacterial activity at these conditions and supports the hypothesis that native DOM is preferentially utilized over introduced DOM. In contrast, first results of similar experiments performed in spring indicate a significant effect of tDOM addition at marine condition, suggesting a strong seasonal dependency of tDOM degradation.

28 MONDAY 9 SEPTEMBER 2013 OS-1A. Ecological consequences of global change in aquatic ecosystems

10:30 MICROBIAL COMMUNITY AND BIOGEOCHEMICAL RESPONSES TO CHANGING CLIMATIC FORCING IN THE TROPICAL, ANOXIC CARIACO BASIN

Gordon Taylor, Stony Brook University (USA) Coauthors: Suter E, Cernadas M, Astor Y, Chistoserdov A, Scranton M

Climatic warming is altering behavior of the Intertropical Convergence Zone (ITCZ) and Hadley cell circulation resulting in weakening Trade Winds in the southern Caribbean Sea. Seventeen years of monthly observations (Project CARIACO) reveal that local responses to climatic forcing include; weakened , warming, enhanced stratification, declining nutrient supply and productivity and a plankton regime shift. In redox transitional waters, oxycline has shoaled as inventories of ammonium have grown and nitrate inventories and bacterial productivity have dwindled. Changing seascape is predicted to alter distributions and activities of microbial clades mediating C, N, and S cycles. Chemoautotrophy links all three cycles and appears to be dominated by thiotrophic proteobacteria (epsilon and gamma). However, chemoautotrophic nitrifiers (beta and gamma proteobacteria and ammonia oxidizing Archaea) and anammox planktomycetes (mostly Scalindua) are common. Talk will explore responses of chemoautotrophs, thiotrophs, nitrifiers, denitrifiers, and anammox bacteria to changes in this system.

29 MONDAY 9 SEPTEMBER 2013 OS-2A. Bacterial diversity: from community composition to community functions

11:15 AUTOTROPHIC ACTIVITY AND PHYLOGENETIC DIVERSITY OF THE SULFIDE-OXIDIZING BACTERIAL GUILD IN THE REDOXCLINE OF A KARSTIC LAKE

Imma Noguerola, Institute of Aquatic Ecology, University of Girona (Spain) Coauthors: Picazo A, Camacho A, Borrego C

Deep karstic lakes exhibit contrasting physical-chemical vertical gradients where microbial populations distribute according to their metabolic and physiological requirements. In these environments, oxic-anoxic interfaces are hot spots of microbial diversity and activity and constitute interesting sites to study the links between community structure and function. Epsilonproteobacteria are key players in biogeochemical cycling of C and S in aquatic environments, especially those characterized by sulfidic redoxclines. Previous studies carried out in different lakes from the Banyoles Karstic System demonstrated that the contribution of dark processes to total autotrophic activity was particularly high at these interfaces. We have studied the seasonal dynamics of Epsilonproteobacteria (EPS) and Green Sulfur Bacteria(GSB) over different year cycles using specific probes for both groups whereas cloning and massive parallel sequencing were used to resolve the phylogenetic community composition. Our results indicate a clear seasonality of EPS and GSB communities, with maximal abundances of EPS in winter (2.45 X 107 cells ml-1, ~78% of total cells) and GSB in spring (1.5 X 108 GSB cells ml-1, ~72% of total cells). Clone libraries from depths where maximal abundances of EPS were measured revealed the dominance of sequences closely related to Arcobacter sulfidicus, a marine, sulfur- oxidizing, autotrophic member of the genus Arcobacter. In situ incubations using radiolabelled bicarbonate further indicated that this population likely assimilated actively CO2 in the dark, being possibly the main responsible of the autotrophic activity at the redoxcline in winter, whereas photoassimilation of inorganic C by GSB likely dominates in summer. Altogether, our data support the key role of Epsilonproteobacteria in linking C and S cycles, extending their influence to freshwater systems characterized by sharp oxic-anoxic interfaces and sulfidic waters.

30 MONDAY 9 SEPTEMBER 2013 OS-2A. Bacterial diversity: from community composition to community functions

11:30 TEMPORAL DYNAMICS OF THE ACTIVITY, DIVERSITY AND FUNCTION OF BACTERIAL COMMUNITIES IN THE NORTH WEST MEDITERRANEAN SEA

Pierre Galand, Observatoire Oceanologique de Banyuls, Banyuls sur Mer (France) Coauthors: Fagervold S, Obernosterer I, Salter I

In ecology, there has always been a strong interest in understanding how communities change at different time scales. But as more information is emerging about the temporal dynamics of planktonic marine bacterial community, the significance of the variation in terms of microbial activity and ecosystem functioning remains poorly explored. We therefore monitored the dynamics of surface bacterial communities over an 8 years period (2004-2011) at the MOLA microbial Observatory in the North West Mediterranean Sea. MOLA is located 20 miles from the coast, and is part of a series of microbial observatories monitored by the Oceanographical Observatory of Banyuls sur Mer, France. The site is visited twice a month to gather environmental data including salinity, temperature, nutrients and bacterial production, and microbial biomass is concentrated on filters for community studies. We used pyrosequencing targeting the 16S rRNA gene to analyze bacterial community composition. By targeting both the DNA and the RNA we aimed at following the dynamics of all Bacteria but also focus on the active members of the community. Our long term monitoring showed that the bacterial communities were characterized by predictable patterns of diversity and composition but that the activity showed a different trend. We could describe two main bacterial seasons: one defined by a low bacterial diversity taking place during summer stratification, the other showing high diversity during winter mixing of the water masses. Each season was characterized by its own assemblage of Bacteria.

31 MONDAY 9 SEPTEMBER 2013 OS-2A. Bacterial diversity: from community composition to community functions

11:45 BACTERIA AT GLACIER SURFACES: MICROBIAL COMMUNITY STRUCTURES AND FUNCTIONS IN DEBRIS COVERED GLACIERS AND CRYOCONITES IN THE ITALIAN ALPS

Andrea Franzetti, University of Milan - Bicocca (Italy) Coauthors: Gandolfi I, Tatangelo V, Bertolini V, Tagliaferri I, Bestetti G, Diolaiuti G, D’Agata C, Mihalcea C, Smiraglia C, Ambrosini R

Sediments occur in different forms on glacier surface. Sediments are abundant at the surface of Debris Covered Glaciers (DCGs) which are mountain glaciers where the ablation area is mainly covered by rock debris. The supraglacial debris of DCGs derives from continuous rock inputs from surrounding slopes and is composed by a mix of coarse and fine particles which is transported down valley by the ice flow. DCGs however represent a minority of glacier in the Italian Alps, which are mostly free from debris. Fine wind-blown particles, the cryoconite, are however abundant on the surface of Debris Free Glaciers (DFGs) and may form cryoconite holes, which are water-filled depressions on the surface of DFGs that form when a thin layer (thinner than the “critical value”) of cryoconite is heated by the sun and melts the underlying ice. There is increasing evidence that cryoconite holes host highly diverse microbial communities and can significantly contribute to global carbon cycle. However, few studies have investigated Alpine cryoconite holes. Similarly, there is almost no study on the microbial communities of the debris cover of DCGs. To fill these gaps in our knowledge, we investigated microbial communities in the debris cover of DCGs and cryoconite holes on three Italian glaciers. We used the Illumina technology to analyse the V5 and V6 hypervariable regions of the bacterial 16S rRNA gene amplified from 38 samples collected in July and September 2009 at different distances from the terminus of two DCGs (Miage and Belvedere, Western Italian Alps). Heterotrophic taxa dominated bacterial communities, whose structure changed during downwards debris transport. We used ARISA fingerprinting and quantitative PCR to describe the structure of the microbial communities and to estimate the number of the total bacteria content and the copy number of Rubisco genes found on 20 cryoconite holes collected on a wide Italian DFG (Forni-Central Alps). pH is the main environmental parameter affecting the structure of communities in cryoconite holes, that is not significantly related neither to the net productivity nor to the respiration rate of the cryoconite holes. Multivariate regression trees (MRTs) confirmed these results showing that samples with pH lower than 4.95 formed a separate cluster with respect to those with a higher pH. The abundance of Rubisco gene was from one to two orders of magnitude less than the total bacteria content. Hence, the overall results suggested that, both in the DCGs and cryoconites, organic carbon is probably provided more by allochthonous deposition of organic matter than by primary production by autotrophic organisms.

32 MONDAY 9 SEPTEMBER 2013 OS-2A. Bacterial diversity: from community composition to community functions

12:00 ECOLOGY AND ECOGENOMICS OF UNCULTURED SULFATE-REDUCING BACTERIA DOMINANT IN EUROPEAN COASTAL SEDIMENTS

Marc Mussmann, Max Planck Institute for Marine Microbiology, Bremen (Germany) Coauthors: Dyksma S, Ovanesov K, Probandt D, Stepanauskas R, Richter M

Permeable shelf sediments are gigantic filters of organic matter. Here, sulfate reduction is the key process in anaerobic carbon mineralization, but still quite little is known about the ecology and ecophysiology of key players of sulfate-reducing bacteria (SRB). Members of the family Desulfobacteraceae are frequently found at sediment surfaces but these are also phylogenetically highly diverse and no distinct group of SRB has been identified that is both widely distributed and abundant. We show for the first time that the uncultured Sva0081-group accounts for up to 10% of total cells in diverse coastal habitats including arctic, subtropical and temperate sediments. Intriguingly, it closely affiliates with endosymbiotic SRB of the gutless marine oligochaete Olavius spp.. In accordance, genome sequences of 6 single cells recovered from a tidal flat display a similar genomic repertoire to the O. algarvensis delta-1 symbiont and provide additional insight into the evolution and biology of these exciting SRB. PCR surveys and isotope tracer experiments further suggest that the Sva0081-SRB are key players in H2 and acetate oxidation in permeable shelf sediments. Genome comparisons with other SRB may reveal features explaining why this group is so successful in sediments and symbioses worldwide.

33 MONDAY 9 SEPTEMBER 2013 OS-2A. Bacterial diversity: from community composition to community functions

12:15 MICROBIAL DIVERSITY AND ECOSYSTEM FUNCTIONING IN DEEP-SEA SEDIMENTS ASSOCIATED TO THE CONDOR SEAMOUNT (AZORES, NE ATLANTIC)

Lucia Bongiorni, CNR-ISMAR Institute of Marine Sciences, Venice (Italy) Coauthors: Manfrin C, Pallavicini A, Paretti P, Santos RS, Stefanni S, Antonioli M, Danovaro R

Seamounts are isolated elevations of the deep-sea characterized by high biological productivity, spatial heterogeneity and the presence of peculiar communities. Although in recent years increasing knowledge has been accumulated on seamounts ecology, information on microbial diversity, its distribution and the relationships between biodiversity and ecosystem functioning are almost entirely unexplored or limited to seamounts with active hydrothermal venting. Prokaryotic abundance and diversity (using molecular fingerprinting techniques and 16S rDNA tag pyrosequencing) was investigated together with abundances of other microbial components (heterotrophic nanoflagellates and protistan-like fungi) in sediments associated to the Condor Seamount (NE Atlantic, Azores). Five different seamount zones, at water depth between 200 and 1900 m, were investigated: the summit, the northern flank and base and the southern flank and base. In addition, a far field site located 10 nautical miles away from the seamount was selected as reference. In order to explore ecosystem functioning we also measured quantity and biochemical composition of sediment organic matter, prokaryotic C production, extracellular enzymatic activities and microbial biomass ratios. All the sampling stations differed in term of grain-size and organic matter quantity and quality. Microbial assemblages changed significantly among seamount areas. Our results pointed to a clear influence of local hydrodynamic conditions and quality of sediment organic matter in shaping the relationship between microbial diversity and ecosystem functioning.

34 MONDAY 9 SEPTEMBER 2013 OS-2A. Bacterial diversity: from community composition to community functions

12:30 LINKS BETWEEN METABOLIC PLASTICITY AND FUNCTIONAL REDUNDANCY IN FRESHWATER BACTERIOPLANKTON COMMUNITIES

Paul del Giorgio, Département des sciences biologiques, Université du Québec , Montréal (Canada) Coauthors: Comte J

Metabolic plasticity and functional redundancy are fundamental properties of microbial communities, which shape their response to environmental forcing, and also mediate the relationship between community composition and function. The actual quantification of these emergent community properties, however, has been elusive, and we thus do not know how these properties vary across bacterial communities, how they relate to environmental gradients or more importantly, how they relate to each other. Here we present an experimental framework that allowed us to simultaneously quantify metabolic plasticity and functional redundancy in freshwater bacterioplankton communities, and to explore connections that may exists between them. We define metabolic plasticity as the rate of change in bacterial single-cell properties relative to changes in community composition. Likewise, we define functional redundancy as the rate of change in carbon substrate uptake capacities relative to changes in community composition. We assessed these two key community attributes in transplant experiments where bacterial communities from lakes, rivers and were exposed to waters from a different system. These environments were all located within the same temperate watershed in southeastern Québec and despite being part of the same hydrological network, differed greatly in terms of water chemistry and resources. Our results show a continuum in the expression of both functional redundancy and metabolic plasticity among bacterial communities. Metabolic plasticity appears to be an intrinsic property of these bacterial communities, and there was some indication that there may be ecosystem-specific patterns, with lake communities appearing to be on average more plastic. In contrast, the expression of functional redundancy appears to be more dependent on environmental factors. Furthermore, there was an overall strong positive relationship between the level of functional redundancy and of metabolic plasticity, suggesting no trade-offs between these community attributes but rather a possible co-selection of these traits at the community level. Collectively our results suggest that the link between community diversity and function may also vary along a continuum, from being very tight, to being weak or absent.

35 MONDAY 9 SEPTEMBER 2013

14:00 N2 FIXATION IN COASTAL MICROBIAL MATS: FROM THE PROCESS LEVEL TO SINGLE CELLS

Invited lecture by Dagmar Wöbken NanoSIMS Group - Department of Microbial Ecology, University of Vienna (Austria)

Photosynthetic microbial mats are laminated, self-sustaining ecosystems with vast phylogenetic and functional diversity that exhibit steep physico-chemical gradients on the millimeter scale. N2 fixation is a key process in these mats that supports the nitrogen demands associated with high primary production. This process has been intensively studied for decades by biogeochemical assays and molecular approaches, such as the sequencing of the functional gene for N2 fixation (dinitrogenase reductase, nifH). However, N2 fixation can be regulated from the transcriptional to the post-translational level, thus the gene distribution or even expression might not accurately reflect the groups actively contributing to N2 fixation. As such, the identity of the active diazotroph(s) in these ecosystems remains unknown. In my talk, I will describe how a multi-disciplinary functional approach enabled us to identify members of the diazotroph community that actively contributed to N2 fixation along with their associated degree of activity. We investigated two mat ecosystems: Elkhorn Slough, California, USA, and Laguna Ojo de Liebre, Mexico. N2 fixation activity was determined by biogeochemical assays. Potential diazotroph bacteria were identified by targeted nifH gene and transcript sequencing, in addition to general metatranscriptome sequence analysis. The in situ activity of 15 identified bacteria with the genetic potential to fix N2 was tested by N2 incubation experiments and subsequent single-cell isotope analysis through nanometer-scale secondary ion mass spectrometry (NanoSIMS). Thereby we were able to combine measurements on the process level down to the single-cell level. We identified a previously unknown cyanobacterium as the major cyanobacterial diazotroph in the mats at Elkhorn Slough. Previous nifH-based investigations of mats at Laguna Ojo de Liebre suggested that visually dominant Lyngbya spp.-related cyanobacteria did not contribute to N2 fixation, rather members of the delta-proteobacteria contributed to this process. Our combined results could not support this hypothesis, but instead identified cyanobacteria related to Lyngbya spp. as the most active N2 fixing microorganisms in this mat type. This work demonstrates that the combination of biogeochemical, molecular and single-cell techniques are powerful tools to define key functional populations in complex microbial communities.

36 MONDAY 9 SEPTEMBER 2013 OS-3. Phototrophic plankton as the movers and shakers in aquatic ecosystems

14:30 LOW TEMPERATURE DELAYS TIMING AND ENHANCES RESPIRATORY COST OF IN UNICELLULAR CYANOBACTERIA

Verena Brauer, University of Amsterdam (The Netherlands) Coauthors: Stomp M, Rosso C, van Beusekom S, Emmerich B, Stal L, Huisman J

Marine nitrogen-fixing cyanobacteria are largely confined to the tropical and subtropical ocean. It has been argued that their global biogeographical distribution reflects the physiologically feasible temperature range at which they can perform nitrogen fixation. In this study we refine this line of argumentation for the globally important group of unicellular diazotrophic cyanobacteria, and derive the following two hypotheses: (i) nitrogen fixation is limited by nitrogenase activity at low temperature and by oxygen diffusion at high temperature, which is manifested by a shift from strong to weak temperature dependence of nitrogenase activity, and (ii) high respiration rates are required to maintain very low levels of oxygen for nitrogenase, which results in enhanced respiratory cost per molecule of fixed nitrogen at low temperature. We tested these hypotheses in laboratory experiments with the unicellular cyanobacterium Cyanothece sp. BG043511. In line with the first hypothesis, the specific growth rate increased strongly with temperature from 18 to 30°C, but leveled off at higher temperature under nitrogen-fixing conditions. As predicted by the second hypothesis, the respiratory cost of nitrogen fixation and also the cellular C:N ratio rose sharply at temperatures below 21°C. In addition, we found that low temperature caused a strong delay in the onset of the nocturnal nitrogenase activity, which shortened the remaining nighttime available for nitrogen fixation. Together, these results point at a lower temperature limit for unicellular nitrogen-fixing cyanobacteria, which offers an explanation for their (sub)tropical distribution and suggests expansion of their biogeographical range by global warming.

37 MONDAY 9 SEPTEMBER 2013 OS-3. Phototrophic plankton as the movers and shakers in aquatic ecosystems

14:45 ULTIMA RATIO SURVIVAL STRATEGY OF FRESHWATER SYNECHOCOCCUS: FROM SINGLE CELLS TO MONOCLONAL MICROCOLONIES

Cristiana Callieri, CNR-ISE Institute of Ecosystem Study, Verbania (Italy) Coauthors: Amalfitano S, Corno G, Bertoni R

Freshwater Synechococcus appear as single-cells of different morphologies and as microcolonies (from 5 to 50 cells). In oligotrophic lakes the seasonal succession of picocyanobacteria is characterized by the dominance of single-cell Synechococcus in spring followed by the appearance of microcolonies in autumn. In eutrophic lakes microcolonies are made harder to single out because of the presence of the bloom-forming colonials of Microcystis or Aphanothece genera. The issue of formation and persistence of picocyanobacterial microcolonies is the object of this article. More specifically, we address the following questions: 1) Are microcolonies derived from a single-cell or do they result from cell-clumping? 2) Which is the most important factor stimulating microcolony formation? 3) Do bacteria associated to Synechococcus have a role in microcolony formation? 4) Are there interactions between different Synechococcus strains? To answer these questions we undertook laboratory experiments with two freshwater single-cell Synechococcus strains with different phycobiliproteins, to study their morphological response to nanoflagellate grazing and UV radiation (UVR). Over five days, we followed the dynamics of single- cells, microcolonies, and predators by flow cytometry, in semi-continuous cultures with four treatments: +UVR, with and without predators; -UVR, with and without predators. The variations of the maximum quantum yield (Fv/Fm) in the treatments were also measured (PhytoPAM) to quantify the fitness of the strains under the different stressing factors. The results obtained allowed us to speculate on the ecological consequences of microcolony formation in the trade-off between Photosystem II activity, growth rate and stress protection of Synechococcus, evaluating the synergistic/antagonistic role of grazing and UVR in microcolony formation. These results can shed light on the dynamics of freshwater Synechococcus morphology in oligotrophic and eutrophic lakes, posing further interesting questions to the microbial ecology of freshwater ecosystems.

38 MONDAY 9 SEPTEMBER 2013 OS-3. Phototrophic plankton as the movers and shakers in aquatic ecosystems

15:00 REGULATION OF LIGHT-STIMULATED FIXATION THROUGH MAJOR CHANGES IN CENTRAL METABOLIC PATHWAYS IN THE HETEROTROPHIC PROTEORHODOPSIN- CONTAINING MARINE FLAVOBACTERIUM DOKDONIA SP. MED134

Jarone Pinhassi, Linnaeus University, Kalmar (Sweden) Coauthors: Palovaara J, Akram N, Baltar F, Forsberg J, Bunse C, González JM

Since the discovery in year 2000 of the proteorhodopsin (PR) gene in marine bacteria, and the subsequent description of its widespread distribution in the oceans, recent work has provided some insight into the benefit of PR phototrophy for promoting growth and survival in different bacteria. Still, little is known about how the harnessing of light energy is regulated; and the metabolic pathways actually mediating the response to light remain unknown. To investigate these issues - and to uncover the role of dissolved organic matter quality for the growth of Dokdonia sp. MED134 in the light and darkness - we carried out experiments with artificial seawater cultures enriched with low concentrations of either a complex (yeast extract and peptone) or a simple (alanine) dissolved organic carbon (DOC) source. Results showed that although light exposure stimulated growth in both seawater media, the light response was much stronger with the single carbon compound alanine. Furthermore, carbon dioxide fixation rates as well as the carbon dioxide fixation:bacterial production ratio increased in the light, implying that the central metabolism was considerably complemented by anaplerotic carbon dioxide fixation (corresponding to approximately 30% of the carbon demand) upon growth in these carbon limited media. Again, these responses were relatively stronger with alanine. We did quantitative PCR to assess the relative expression of 11 key genes involved in bicarbonate uptake, anaplerotic carbon dioxide fixation and alternative TCA cycle pathways. The PR gene was up-regulated nearly 40-fold in the light in seawater with either complex or simple DOC. The genes encoding isocitrate lyase and malate synthase (the two key genes in the glyoxylate shunt) were also strongly up-regulated in the light (40- to 100-fold compared to darkness) but only in seawater with alanine. Thus, the relatively higher light-induced growth responses with alanine seem to be primarily mediated by the glyoxylate shunt function. In particular, the light-dependent upregulation of genes in the glyoxylate shunt allow for house holding with carbon atoms thanks to the ATP provided by PR phototrophy. Collectively, these findings provide novel insights into the interactions between DOC quality and the genetic regulation of central metabolic pathways that critically determine the fitness of bacteria engaging in PR phototrophy in the ocean surface.

39 MONDAY 9 SEPTEMBER 2013 OS-3. Phototrophic plankton as the movers and shakers in aquatic ecosystems

15:15 PHOTOFERROTROPHY AND Fe-CYCLING IN A FRESHWATER COLUMN

Marc Llirós, Autonomus University of Barcelona (Spain) Coauthors: Crowe SA, García-Armisen T, Darchambeau F, Morana C, Borrego C, Triadó-Margarit X, Bouillon S, Borges AV, Servais P, Canfield D, Descy JP

Emerging insight shows that ferruginous (anoxic and iron-rich) conditions dominated ocean chemistry throughout the first 3.5 billion years of Earth evolution. Modern ferruginous water masses are rare, but detailed examination of these oddities, especially of photoferrotrophs and their Fe-reducing respiratory counterparts, could yield important insights into the early evolution of life on Earth and its impact on global element cycles. Here, we describe an abundant microbial community of pelagic photoferrotrophic and Fe-reducing microbes in a freshwater basin in East Africa (Kabuno Bay, DR Congo), recently discovered to be ferruginous. The application of culture- dependent and -independent techniques allowed the identification of active photoferrotrophs genetically similar to laboratory cultures of Chlorobium ferrooxidans, the only member of the Chlorobi previously known to conduct photoferrotrophy. The Kabuno Bay photoferrotrophic Green Sulfur Bacteria (GSB) community ranged between the 16.2% and 38.3% of the entire bacterial community retrieved by 454 pyrotag analyses of the euphotic Fe-rich chemocline of Kabuno bay. The GSB maximum coincided with high rates of ferrous Fe oxidation and bacterial production. Up to 60% of total depth integrated BP is carried out at the depths where photoferrotrophic GSB dominate. Main bacterial groups involved in were also recovered from the upper oxic-anoxic transition zone, but in contrast to the GSB community, other microorganisms typically implicated in the were only present at low relative abundances. DAPI counts revealed a high microbial biomass in the water column of Kabuno bay, which we speculate supports large populations of pelagic iron-reducers. Reactive iron oxides, however, are exhausted within the chemocline and excess organic matter is thus channelled through mineralization by methanogenesis directly in the water column. Our study documents for the first time that photoferrotrophs are suited to pelagic lifestyles and putatively possess a low- light adapted light harvesting apparatus. That pelagic carbon mineralization is channelled through methanogenesis even under ferruginous conditions impling that gaseous reduced equivalents can escape to the atmosphere, allowing excess ferric iron to be exported to sediments such as Banded Iron Formations. In this way, photoferrotrophs could contribute to the overall oxidation of the Earth’s surface prior to the oxygenation of the atmosphere.

40 MONDAY 9 SEPTEMBER 2013 OS-3. Phototrophic plankton as the movers and shakers in aquatic ecosystems

15:30 LOW PIGMENTATION - MAJOR CONTRIBUTION: SURFACE PROCHLOROCOCCUS DOMINATE CO2 UPTAKE ACROSS THE LOW LATITUDE ATLANTIC OCEAN

Manuela Hartmann, National Oceanography Centre, Southampton (UK) Coauthors: Gomez-Pereira P, Grob C, Ostrowski M, Tarran G, Scanlan D, Martin A, Zubkov M

Oligotrophic gyres cover significant areas (>40%) of the and are gradually expanding in size most likely as a reaction to changing climate conditions. Phytoplankton in these regions constitute a taxonomically diverse conglomerate of prokaryotic and eukaryotic organisms dominated by the most abundant chlorophyll-containing microorganisms on the planet: the Prochlorococcus cyanobacteria. Adapting to the strong tropical sunlight in the surface water layers, these bacteria have reduced the amount of cellular photosynthetic pigments to virtually undetectable levels. Scarce measurements of chlorophyll-richer Prochlorococcus in the deeper part of the photic layer indicate a large capacity for CO2 fixation. However, their ecological significance in the surface layer remains unknown. Here, we present direct evidence that, despite their low chlorophyll contents in the surface layer, Prochlorococcus are more efficient CO2 fixers than eukaryotic algae and are responsible for half of the biological CO2 fixation in the open Atlantic Ocean, placing them among the key primary producers of Earth’s ecosystems.

41 MONDAY 9 SEPTEMBER 2013 OS-1B. Ecological consequences of global change in aquatic ecosystems

16:15 TESTING THE EFFECT OF THE PUYEHUE-CORDÓN CAULLE MEGA-ERUPTION ON MICROBIAL COMMUNITIES OF PATAGONIAN LAKES

Beatriz Modenutti, CONICET- Comahue University, Bariloche (Argentina) Coauthors: Bastidas Navarro M, Sol Souza M, Balseiro E

On 4 June 2011, a mega-eruption in the Puyehue volcanic complex (Chile) discharged massive amounts of ash and pumice to the surrounding landscape. As a consequence, large and small lakes in the area were partially or completely covered by a floating pumice layer. In nature, the event brought about increases in phosphorus (P) concentrations, and decreases in solar irradiation in the surface layers in the heavily affected lakes. To test the mechanisms of these responses on the microbial community, we performed an outdoor experiment in 20 L mesocosms in three treatments: 1- full solar radiation (equivalent to the mean irradiance received in lake mixolimnion), 2- covered with pumice, and 3- dark. We used natural lake water of two lakes that differed in dissolved organic carbon concentration: Lake Gutiérrez and Lake Escondido. We measured nutrient concentration, alkaline phosphatase (APA) and β-glucosidase (BG) activities and determined the different component of the microbial food web. In addition, we performed laboratory experiments measuring bacteria respiration and organic matter lability. Results showed similar trends between lakes, though intensity of processes may differ, with significant differences between treatments. While the treatment full solar radiation did not exhibited significant changes, under the pumice we observed an increase of 85% of P concentration with a concurrent decrease in APA activity. During the first week of experimentati on we observed a decrease in chlorophyll a concentration with an increase in dissolved organic carbon, and consequently bacteria respiration and BG activity increased. After 15 days of experimentation, we observed in the treatment covered by pumice a recover of nanoflagellates with a concurrent decrease in P, while in the dark this recover was not observed. These results indicated that the effect of volcanic eruptions may affect all the microbial food webs, although processes occurred with a higher significant strength in the lake with high dissolved organic matter concentration.

42 MONDAY 9 SEPTEMBER 2013 OS-1B. Ecological consequences of global change in aquatic ecosystems

16:30 RESPONSE OF RARE VERSUS ABUNDANT BACTERIOPLANKTON TO DISTURBANCES IN A MEDITERRANEAN COASTAL SITE

Federico Baltar, Linnaeus University, Kalmar (Sweden) Coauthors: Palovaara J, Vila-Costa M, Calvo E, Pelejero C, Marrasé C, Salazar G, Gasol JM, Pinhassi J

Anthropogenic impacts, such as ocean acidification and eutrophication, menace the structure and functioning of marine ecosystem and the consequential role of the ocean in the global carbon cycle. Although marine bacteria play a paramount role in marine carbon cycle, it is not clear if their diversity will be affected by changes in pH or/and nutrient concentration. Despite their large diversity, the ecological significance of rare bacteria remains elusive. There is recent evidence suggesting that both abundant (i.e., >1% relative abundance) and rare members (i.e., <0.1% relative abundance) of a bacterial community can respond to disturbances, but their corresponding degree of responsiveness is unknown. We studied the response of a coastal Mediterranean bacterioplankton community to environmental disturbances (i.e., nutrient addition and/or acidification) in three mesocosm experiments (two in winter and one in summer conditions), at the class, genus and species (operational taxonomic units, OTUs, defined at 97% sequence similarity) level by 454 pyrosequencing of 16S rRNA. Even if the main responding classes were the same in the three experiments (i.e., Gammaproteobacteria, Alphaproteobacteria and Flavobacteria), dissimilar genera among the same classes became dominant in different experiments, suggesting the importance of the taxonomical resolution when studying the response of bacterioplankton communities to disturbances. Although nutrient additions had a stronger effect on community structure than acidification, pH variations had important influences on some specific members (like the numerically abundant SAR 86), suggesting that acidification could also have implications in the community by affecting abundant members. Even though the proportion of rare members becoming abundant could be relevant under some particular disturbances, most of the OTUs responding and becoming abundant were already abundant (i.e., >1% relative abundance) or common (i.e., <1-0.1% relative abundance) in the original community. These findings suggest that an important fraction of the rare biosphere shows a permanently rare life strategy, and that the fraction of common members (i.e., the non-abundant non-rare) harbors a population particularly prone to respond to disturbances, therefore playing a key ecological role for the community.

43 MONDAY 9 SEPTEMBER 2013 OS-1B. Ecological consequences of global change in aquatic ecosystems

16:45 CONNECTIONS OF GREENHOUSE GAS EMISSIONS AND MICROBIAL GENES IN BOREAL LAKES

Jatta Karhunen, University of Jyväskylä (Finland) Coauthors: Syväranta J, Devlin S, Jones R, Rissanen A, Tiirola M

Boreal lakes are characterized by their dark water color and oxygen deficiency in the hypolimnion. The steep oxygen stratification enables development of distinct microbial communities and biogeochemical processes in specific water layers. Many boreal lakes are important sources of greenhouse gases (carbon dioxide CO2, CH4 and nitrous oxide N2O) to the atmosphere. The greenhouse gas production and reduction is microbial mediated and takes place either in the water column of the stratified lakes and/or at the sediment. We studied the correlation between these emissions and specific genes or microbial groups regulating the emissions using cultivation- independent molecular methods, like qPCR and sequencing methods. The studies were conducted at different scales ranging from laboratory incubations to whole lake experiments and inter-lake comparisons. We investigated the role of anaerobic phototrophic green sulfur bacteria (GSB) in the anoxic primary production, the quantity of methanotrophs in regulating , and the relationship of denitrifying genes (nirS, nirK and nosZ) in N2O production. Even though the measured primary production rates by GSB communities were low and their impact on greenhouse gas emissions is unclear, the high bacteriochlorophyll concentrations and 16S rRNA gene sequencing indicated high biomasses of GSB in the hypolimnion of most of the studied lakes. Of the environmental and molecular factors controlling denitrification and relative N2O production in our study lakes, nitrate concentration (reflecting the land use in the catchment area) was the main factor affecting also the relationship between the denitrification genes ((nirS+nirK) / nosZ).

44 MONDAY 9 SEPTEMBER 2013 OS-1B. Ecological consequences of global change in aquatic ecosystems

17:00 WHAT BACTERIA CAN (NOT) TELL US ABOUT ENVIRONMENTAL WARMING IN SHALLOW LAKES

Cecilia Alonso, CURE - University of the Republic (Uruguay) Coauthors: Lacerot G, Meerhoff M

Shallow lakes represent one of the most widespread inland water bodies in the world landscape, being rapidly affected by external perturbations such as climate change. These ecosystems are complex given their potential of shifting between alternative states, with different food web configurations. In this work, we aimed to test a series of theoretical predictions of the metabolic theory of ecology (MTE) of changes at the community level with an increase in ambient temperature along the globe. We conducted a literature meta-analysis looking for the changes of different traits of the bacterioplankton community of shallow lakes under diverse climates. This exercise revealed very different amounts of information for the four target variables (density, biomass, size, and community richness) in studies which also measured environmental parameters relevant to our analysis. Data on bacterial biomass and size were quite scarce. Also, data on microbial community richness (usually estimated through molecular fingerprinting methods) were restricted to few studies, mostly carried on temperate environments. Furthermore, in most of the studies, those approaches were seldom combined, thus resulting in fragmentary information of a given bacterial community. As a consequence, only the data recovered for bacterial abundance allowed us to visualize trends with respect to climate change. From this survey became evident that bacterial abundance does vary significantly with latitude, in an inverse relationship. This correlation is also clear when grouping the systems according to the Köppen’s climatic zones. The main factors behind this pattern were identified by Spearman's correlations and stepwise multiple regressions performed with bacterial abundance and the following parameters: latitude, altitude, lake area, water temperature, conductivity, total phosphorous, total nitrogen, chlorophyll a (chla), and dissolved organic carbon (DOC). The Spearman's correlations indicated that bacterial abundance significantly declined with increasing latitude, while significantly increased with increasing DOC, temperature, conductivity and chla. From stepwise multiple regressions it was possible to determine that temperature and chlorophyll a were the factors explaining most of the latitudinal variation in bacterial abundance. These findings contradict the predictions of the MTE, however they should be taken with caution, as a positive correlation of temperature and DOC might blur the purely climatic signal.

45 MONDAY 9 SEPTEMBER 2013 OS-1B. Ecological consequences of global change in aquatic ecosystems

17:15 DIVERSITY OF MICROBIAL COMMUNITIES IN GLACIER-FED LAKES

Hannes Peter, Institute of Ecology - University of Innsbruck (Austria) Coauthors: Moya L, Dittmar T, Sommaruga R

One of the most prominent signs of climate change is the retreat and thinning of glaciers. Deglaciation may impact aquatic ecosystems by enlarging existing lakes or by creating new lakes where topography is suitable. Glacier-fed lakes are characterized by a high content of suspended minerogenic particles, so-called “glacial flour”, resulting from erosion of the subglacial bedrock. The high turbidity drastically reduces light availability for primary production, which dominates as a source of dissolved organic carbon (DOC) in transparent high alpine lakes. Surprisingly, little knowledge exists about the ecology of glacial turbid lakes and the changes that occur in biodiversity when they shift to clear conditions. Throughout the ice-free season of 2012, we repeatedly sampled four lak es in the Austrian Alps which originated from deglaciation. The lakes are interconnected and situated along an altitudinal gradient between 2200 and 2600 m a.s.l. Three lakes receive glacial melt water and are turbid, whereas one lake receives water through seepage and is transparent. Using massive parallel sequencing of the 16S rRNA and rDNA, we followed community dynamics of active and passive fractions of bacterial and archaeal communities. We hypothesized that microbial community composition and diversity shift along the turbidity gradient, mediated by the availability of autochthonous dissolved organic carbon. We measured key environmental parameters and characterized organic carbon using ultra-high resolution mass spectrometry. Glacial turbid lakes are highly dynamic in their environmental conditions, dictated by the melting of the glacier, which results in pronounced changes in temperature, DOC quantity and composition, turbidity, light and nutrient availability over the course of a season. These dynamics are tracked by changes in bacterial abundance and production. In this study, we present first results of the coupling of environmental conditions in lakes influenced by glacial melt water with dynamics of microbial community composition and diversity.

46 TUESDAY 10 SEPTEMBER 2013

9:00 OPENING PANDORA’S BLACK BOXES: WHAT HAVE THEY DONE TO OUR “ACTIVE” BACTERIA?

Invited lecture by Jakob Pernthaler Limnological Station, University of Zurich (Switzerland)

The determination of the bulk activities and production of bacterioplankton assemblages has formed a backbone of traditional aquatic microbial ecology in the context of carbon cycling and microbial food webs. With the rise of molecular techniques to identify microbial genotypes and their specific traits, these community-level analyses (often derogatively termed “black box” approaches) have increasingly fallen into disgrace. Undoubtedly, the resulting forests of phylogenetic trees, the microphotographs of green and orange dots, and the arcane multivariate statistical biplots have greatly promoted our conceptual understanding of microbial diversity, of the various pro- and eukaryote players in pelagic habitats and of their respective interactions. However, there are also things we might have lost in the fire of enthusiasm for microbial community composition and individual taxa. While there is no going back to concepts that ignore the differences between sympatric bacterioplankton populations (such as the notion of the ”active bacterial fraction”) it might nevertheless be profitable to apprehend their respective roles in the biogeochemical processes that microbial ecologists used to study decades ago. In other words, it might be rather dark inside the “black box” without a simultaneous appreciation of the specific interactions between pelagic bacteria and their abiotic environment, both in qualitative and quantitative terms. Unfortunately, important aspects of this environment seem to represent yet another “black box”, e.g., the composition and turnover of organic matter. Moreover, that box seems to be predominantly of interest for (geo)chemists, whereas microbial ecologists of late have primarily been flirting with bioinformaticians. Is it, therefore, time for a ménage a trois in aquatic microbial ecology?

47 TUESDAY 10 SEPTEMBER 2013 OS-4. Bacterial life strategies in relation to carbon flow to higher trophic levels

9:30 INTERACTIONS BETWEEN RECALCITRANT AND LABILE ORGANIC CARBON IN STREAM BIOFILMS

Karoline Wagner, Department of Limnology, University of Vienna (Austria) Coauthors: Bengtsson M, Burns N, Herberg E, Wanek W, Battin T

In recent years the importance of inland waters in the global carbon cycle has been increasingly recognized. In streams, biofilms constitute the dominant mode of microbial life and play a key role in stream carbon fluxes. In these biofilms, heterotrophic bacteria and algae coexist in close spatial proximity and the microbial communities are exposed to both recalcitrant DOC (RDOC) of terrestrial origin and labile algal exudates. In soils, degradation of recalcitrant carbon is known to be affected by the availability of labile carbon sources. Such interactions are described as priming effects (PEs). Mounting evidence suggests that PE could also be an important mechanism in aquatic ecosystems but there are still few studies addressing this topic. Therefore, we investigated if stream biofilms could be hotspots for PE. Two experiments were designed to investigate if stream biofilms could mediate priming in the hyporheic and/or the of streams. In both experiments, a 13C-labeled plant extract was added as RDOC source. This allowed separation of the different carbon pools in the C mass balance and detection of PE. Plug-flow bioreactors were used to mimic stream sediments (), in which the heterotrophic bacterial communities were exposed to RDO13C and labile dissolved organic carbon (LDOC). Microcosms with benthic biofilms were kept under a gradient of light intensities to stimulate differential algal exudation and exposed to RDO13C. Our results suggest that priming effects are not of major importance in the hyporheic zone. Additions of LDOC to the bioreactors did not lead to a significant increase in RDOC uptake. However, in benthic biofilms higher uptake of RDOC was observed during day when algal exudation was higher than during night. Further, phenol oxidase activity measurements were also higher during day, which indicates more breakdown of RDOC by the microbial communities. Both studies shed light on carbon and inorganic nutrient dynamics in streams, highlighting that stream biofilms are not only processing solutes, but are also important sources of DOC and inorganic nutrients, which can lead to interesting interactions of different carbon pools, like the priming effect.

48 TUESDAY 10 SEPTEMBER 2013 OS-4. Bacterial life strategies in relation to carbon flow to higher trophic levels

9:45 DIFFERENTIAL COMMUNITY RESPONSE OF A NATURAL FLAGELLATE ASSEMBLAGE TO BACTERIAL FOOD QUALITY WITH A FOCUS ON CLOSELY RELATED LIMNOHABITANS BACTERIA

Karel Simek, Biology Centre AS CR, Hydrobiological Institute, Ceske Budejovice (Czech Republic) Coauthors: Kasalický V, Jezbera J, Hornak K, Nedoma J, Hahn M, Bass D, Jost S, Boenigk J

Different bacterial strains can have different nutritional value as food for heterotrophic nanoflagellates (HNF), thus modulating HNF growth and community composition. We proposed an innovative experimental design to examine the influence of prey food quality using four Limnohabitans strains, one Polynucleobacter strain and one freshwater actinobacterial strain (Luna 2 cluster) on growth (growth rate, length of lag phase, and biomass yield) and community composition of a natural HNF community from a freshwater reservoir. Pyrosequencing of eukaryotic SSU rRNA amplicons was used to assess time-course changes in HNF community composition. All four Limnohabitans strains and the Polynucleobacter strain yielded significant HNF community growth while the actinobacterial strain did not support the HNF growth though it was clearly detected by FISH probes in flagellate food vacuoles. Notably, even within the Limnohabitans strains we found significant prey-related differences in HNF growth parameters, which could not be only related to size or shape of the bacterial prey. Sequence data characterizing the HNF communities showed also that not only very different strains but even closely related bacterial prey items induced highly significant differences in the resulting community composition of flagellates. Generally, Stramenopiles dominated the communities and phylotypes from Chrysophyceae closely related to Pedospumella or Spumella-like subclusters D and E2 were most abundant bacterivorous flagellates rapidly reacting, with doubling times of 6-11 h, to addition of the bacterial prey of high food quality. Overall, our experimental approach combined with pyrosequencing of the grazer community could provide important insights regarding the question which bacterial strains are active in carbon transfer to the grazer food chain in a particular aquatic system, and which flagellate groups are the key players in the trophic transfer.

49 TUESDAY 10 SEPTEMBER 2013 OS-4. Bacterial life strategies in relation to carbon flow to higher trophic levels

10:00 MICROBIAL UTILIZATION OF ATMOSPHERIC GAS-PHASE ORGANIC CARBON IN THE SURFACE OCEAN

Jesús M. Arrieta, IMedEA (CSIC-UIB), Esporles (Spain) Coauthors: Duarte CM, Sala MM, Dachs J

Large fluxes of atmospheric gas-phase organic carbon (GOC) entering the ocean have been reported recently, indicating that the ocean may be for some of these organic compounds. Since prokaryotes are the only significant consumers of dissolved organics in the ocean we hypothesized that some of these GOC compounds may be utilized by oceanic prokaryotes. Experimental evaluations of GOC utilization at different locations in the NE Subtropical Atlantic Ocean, the Arctic Ocean and the Mediterranean Sea resulted in large shifts in carbon demand and growth efficiency when compared to controls containing only non-volatile DOC. GOC was a major source of carbon for heterotrophic prokaryotes, fuelling up to 27% of the prokaryotic carbon demand in our experiments. Moreover, we estimated that a large part of the atmospheric GOC entering the ocean was consumed within the mixed layer at most locations in our study, increasing the effectiveness of the surface ocean as a sink for these compounds. Common procedures in biogeochemical studies such as vacuum filtration, remove volatile compounds from incubations while the most common methods to measure DOC stocks exclude volatile organics thus, keeping these labile organic substances out of the carbon budget. Our results indicate that the current methodologies used to estimate DOC stocks and microbial mediated DOC fluxes need to be carefully re-evaluated since microbial consumption of gaseous atmospheric organic may result in fluxes of organic carbon large enough to affect significantly the global carbon budget.

50 TUESDAY 10 SEPTEMBER 2013 OS-4. Bacterial life strategies in relation to carbon flow to higher trophic levels

10:15 FRESHWATER ACTINOBACTERIA: FROM UNCULTIVATED TO ENIGMATIC

Sarahi L Garcia, FSU Jena and JSMC (Germany) Coauthors: McMahon KD, Grossart HP, Warnecke F

Actinobacteria within the acI lineage are often numerically dominating freshwater ecosystems, where they can account for >50% of total bacteria in the surface water. Despite their importance there are no reports on the isolation of acI. We thus set out to use single cell genomics to gain insights into their genetic make-up, with the aim of learning about their physiology and ecological niche. From the single cell genome, a representative from acI-B1 was analysed and the metabolic reconstruction gave us some hints about the niche of this organism. With this information, enrichments were established and after a few months we were able to obtain a highly enriched co-culture of acI-B2. To our surprise acI-B2 grows in high abundance and quite fast together with yet another highly abundant freshwater bacteria, Polynucleobacter sp. However to detect the growth of both organisms a qPCR assay was necessary, since the density of the culture is relatively low. Some tests have been done on these co-culture and some interesting features of acI have been confirmed. There are still many questions that remain to be answered for acI and one of the most intriguing would be the character of its interaction with Polynucleobacter sp. or other bacteria in the environment.

51 TUESDAY 10 SEPTEMBER 2013 OS-4. Bacterial life strategies in relation to carbon flow to higher trophic levels

10:30 THE ECOLOGICAL ROLE OF PELAGIC METHYLOTROPHIC ULTRAMICROBACTERIA ASSESSED BY HIGH-RESOLUTION IN SITU ANALYSIS AND STUDIES ON ISOLATED STRAINS

Michaela Salcher, Limnological Station, University of Zurich (Switzerland) Coauthors: Posch T, Pernthaler J

Pelagic freshwater bacteria are important sources but also sinks for major nutrients and substrates in lakes. Methylotrophic bacteria can be key players in the carbon cycle, as C1-compounds are used as sole sources of carbon and energy gain. Members of the ubiquitous betaproteobacterial tribe LD28 seem to be highly relevant for the turnover of methanol, a degradation product of pectin and lignin. We followed the spatio-temporal distribution of these microbes in Lake Zurich, Switzerland, in a high-resolution sampling campaign during 4 consecutive years (992 individual samples). Members of the LD28 tribe were present in variable abundances (up to 1.1 x 105 cells ml- 1) with pronounced peaks after phytoplankton blooms in spring and at the onset of mixis in late autumn. Interestingly, these microbes were rare in the warm stratified water layers during summer, but colonized the deep and cold hypolimnion, hinting at cold-stenothermic growth. More than 90 strains of these so far uncultivated bacteria were isolated from the pelagial of Lake Zurich by dilution to extinction. The isolates showed very slow growth (0.4 d-1 maximum growth rate) and were of conspicuous small cell size (0.05 µm3). They did not incorporate amino acids or sugars, but showed enhanced growth after the addition of methanol to sterile lake water, reflecting an obligate methylotrophic lifestyle. Phylogenetic analysis of the 16S rDNA proved a close relation to the ubiquitous marine OM43 lineage and the separation into 2 distinct phylotypes, both of which seem to be species of the same genus. As the closest relative (Methylotenera mobilis) has sequence similarities of <95%, we propose the establishment of a new genus with 2 species, i.e., Candidatus Methylopumilus planktonicus and Candidatus Methylopumilus turicensis.

52 TUESDAY 10 SEPTEMBER 2013

11:15 A SYMBIOTIC ADVANTAGE: DIATOMS AND CYANOBACTERIA WORK TOGETHER TO MAKE THE MOST IN A NITROGEN DEPLETE OCEAN

Invited lecture by Rachel Foster Department of Biogeochemistry, Max Planck Institute for Marine Microbiology - Bremen (Germany)

Hemiaulus spp. diatoms with associated cyanobacterial Richelia intracellularis symbionts are widely distributed in tropical and subtropical seas where nutrient concentrations are low or often undetectable. Since the symbionts are heterocystous, and therefore capable of nitrogen fixation, the function of the symbiont for the host was presumed to supply fixed N to the host, but the degree to which the symbiont supports the growth of the host and the benefit to the symbionts was unknown. We use imaging by nanometer scale secondary ion mass spectrometry (nanoSIMS) on field populations of symbiotic Diatoms incubated with 15N2 and 13-bicarbonate to better understand the basis of the relationship. In addition, we use eukaryotic protein inhibitor to resolve the function of the host for the symbiont. In parallel, we also estimate transcript abundance and recently identified significant differences in both genome size and content in the Richelia genome, compared to another diatom symbiont, Calothrix. Combined, the results are allowing us a better understanding of the activity and nutrient exchanges in the partnerships. These symbioses are important models for molecular regulation and nutrient exchange in symbiotic systems.

53 TUESDAY 10 SEPTEMBER 2013 OS-5. Giving and getting: lifestyles of attached and symbiotic microbes

11:45 STEPPING OUT FROM TEP

Ilana Berman-Frank, Bar Ilan University, Ramat Gan (Israel) In memory of Tom Berman

For the past 12 years Tom Berman had been immersed in studying various aspects of Transparent Expolymer Particles (TEP) in aquatic environments and their role in aquatic biofilm development (coauthoring ~ 20 related publications). Tom’s interest in TEP/microgels came from earlier studies on carbon and nitrogen cycling. Thus he examined the role of TEP in the freshwater Lake Kinneret (Israel) and then later showed the importance of these particles in organic matter cycling and transportation also in the oligotrophic Gulf of Eilat (Red Sea) and Eastern Mediterranean sea. These studies led to the insight that TEP microgels (abundant in both seawater and freshwater are intimately involved in the formation of aquatic biofilms, a multi-billion dollar problem in the water industry, and that TEP is indeed a critical factor in aquatic biofilm development. Tom’s research bridged the gap between studies of TEP in the natural aquatic milieu and its application in the water industries. Subsequently, the importance of minimizing TEP levels in feedwater reaching sensitive surfaces (e.g. reverse osmosis membranes in desalination plants) is now becoming recognized in the water industry. This applied research also led to a revised paradigm of aquatic biofilm formation as facilitated by TEP. In this brief presentation I shall highlight Tom’s contributions to these issues as well as some of his ideas which he planned on presenting at SAME13 entitled “Bridging concepts of Particulate Organic Material: Hot Spots, Protobiofilms, Biopolymer Gel Networks, Self Assembled Microgels (SAGs), exopolymer substances (EPS), TEP and other microscopic particles forming sites for microbial colonization in aquatic environments”.

54 TUESDAY 10 SEPTEMBER 2013 OS-5. Giving and getting: lifestyles of attached and symbiotic microbes

12:00 A MULTIDISCIPLINARY APPROACH TO STUDY CORAL SURFACE MUCUS AS A MICROBIAL NICHE

Pedro Frade, Department of , University of Vienna (Austria) Coauthors: Roll K, Garcia J, Birgel D, Herndl GJ

At the interface between the coral host epithelium and the seawater environment, coral surface mucus supports a microbial biofilm that acts as barrier against a wide range of environmental stresses. The main goal of this study was to link the dynamics in the composition of the coral mucus layer, in its secretion and release patterns, to related changes in the prokaryotic community structure and function. The mucus composition of several Caribbean coral species has been analyzed. Glycosyl composition analysis by GC-MS resolved two phylogenetically broad groups of species where the main mucus carbohydrate was either galactose or fucose. GC-MS analyses of the total lipid extracts of mucus revealed species-specific composition in terms of relative amounts of esters, sterols and fatty acids. Interestingly, no bacterial-derived lipid biomarkers were found. Species-specific differences in the thickness of the mucus layer and the potential of the mucus to serve as carbon source for heterotrophic microbes were detectable. Massive parallel amplicon-based metagenomic 16S-rRNA (gene) analysis (Roche454 GS-FLX+ platform) was carried out on 132 mucus samples collected from the coral species along a depth gradient. Sequence analysis is currently in progress. Preliminary results suggest that mucus- associated prokaryotic communities vary substantially among host species with substantial differences in the community structure between Bacteria and Archaea. While Bacteria seem to be more dependent on host-related factors, Archaea rather relate to environmental input. Understanding the distribution and abundance of bacterial and archaeal communities thriving on coral mucus and linking them to the dynamics of the mucus layer as a micro-niche will help elucidating the host- and microbial community-specificity, microbial niche diversification and microbial succession and ultimately, the role of mucus associated microbes in the biogeochemical cycles in the ecosystem.

55 TUESDAY 10 SEPTEMBER 2013 OS-5. Giving and getting: lifestyles of attached and symbiotic microbes

12:15 MÉNAGE-À-TROIS: THE AMOEBA NUCLEARIA SP. FROM LAKE ZURICH WITH ITS ECTO- AND ENDOSYMBIOTIC PARTNERS

Sebastian Dirren, Limnological Station, University of Zurich (Switzerland) Coauthors: Salcher MM, Pernthaler J, Schweikert M, Posch T

We present a fascinating triad relationship between a eukaryotic amoeba and its two bacterial partners. As the benthic amoeba feeds on toxic filamentous cyanobacteria (Planktothrix rubescens), we hypothesized that symbiotic bacteria may be involved in the degradation of toxic metabolites. For the identification of the three microbial partners we used morphological features as well as molecular methods like cloning and sequencing of the small subunit rRNA, and fluorescence in situ hybridisation. The morphological characteristics of the amoeba isolated from Lake Zurich allowed for a confident affiliation to the genus Nuclearia. However, for species identification we obtained an ambiguous image. Sequence comparisons favoured the affiliation of our isolates to the species N. thermophila but several observed morphological features are in strong contradiction to the original description. Isolates from Lake Zurich live in symbiosis with ecto- and endosymbiotic bacteria. The ectosymbiont is localized regularly arranged inside a layer of extracellular polymeric substances provided by the amoeba. It was identified as Paucibacter toxinivorans, a bacterium that was originally isolated through enrichment with the cyanobacterial toxin microcystin. Thus, P. toxinivorans may indeed increase the fitness of the nucleariid amoeba, being involved in the detoxification of its toxic food. The endosymbiont was observed by transmission electron microscopy to be enclosed in symbiosomes inside the amoebal cytoplasm. According to the 16S rDNA sequence, this bacterium belongs to Gammaproteobacteria but it could not be grouped into any established genus. Therefore, we propose the provisional name Candidatus Companero nuclearis for these bacteria that have until now never been found free- living nor in a symbiotic association. Additionally, we have never observed endosymbiont-free amoebae of our isolates, which might indicate that this interaction is an obligate symbiosis. In contrast, ectosymbiotic bacteria may be lost, still enabling the amoeba to survive. We highlight that the presented microbial Ménage-à-trois may serve as a wonderful model system to study very basic symbiotic interactions between pro- and eukaryotes.

56 TUESDAY 10 SEPTEMBER 2013 OS-5. Giving and getting: lifestyles of attached and symbiotic microbes

12:30 PLOS ONE AND FRONTIERS: OPEN ACCESS JOURNALS FOR AQUATIC MICROBIAL ECOLOGY

Pre-Lunch Talk by Stefan Bertilsson, SAME13 Scientific Committee and University of Uppsala (Sweden)

57 TUESDAY 10 SEPTEMBER 2013

14:00 NEW INSIGHTS ON THE DIVERSITY OF MARINE VIRUSES AND THEIR IMPACT OF ON THE FUNCTIONING OF THE GLOBAL BIOSPHERE

Invited Lecture by Roberto Danovaro Marine Sciences Department, Polytechnic University of Marche (Italy)

Viruses are by far the most abundant “life forms” in the world’s oceans (approximately 4x1030 viruses), exceeding prokaryotic abundance by at least one order of magnitude. Increasing evidence indicates that viral infection may be responsible for the high mortality of autotrophic and heterotrophic organisms in surface oceans, with cascading effects on carbon cycling and nutrient regeneration. Viral lysis of infected microbes transforms their cell contents and biomass into organic detritus, which can influence the pool of organic carbon in the ocean and the pathways of organic matter diagenesis (viral shunt). Recent studies reported that viral production in deep-sea benthic ecosystems worldwide is extremely high, and that viral infections are responsible for the abatement of 80% of prokaryotic heterotrophic production. Similar processes have been reported for different very common and “extreme” habitats all over the world. It is increasingly evident that prokaryote- interactions and viral infections of larger life forms can regulate can regulate ecosystems’ metabolism and functioning. Available information also suggests that marine viruses can influence directly and indirectly biogeochemical cycles, capacity of the oceans and the gas exchange between the ocean surface and the atmosphere. Here I will provide novel information about viral diversity in oceanic biomes and discuss how marine viruses can influence global biogeochemical cycles, and the overall functioning of our biosphere.

58 TUESDAY 10 SEPTEMBER 2013 OS-2B. Bacterial diversity: from community composition to community functions

14:30 ECOLOGICAL INTERPRETATION OF MICROBIAL CO-OCCURRENCE PATTERNS BY NETWORK MODELLING

Alexander Eiler, Uppsala University (Sweden) Coauthors: Bertilsson S, Jones RI, Peura S

Besides complex co-occurrence patterns have been described among microbes in natural communities, little is known about their relevance for ecosystem functioning and stability. We used a large community dataset of absolute abundance estimates, including bacteria, phytoplankton and , from the epilimnion of a boreal humic lake to capture relationships between pairs of microorganisms using the maximal information coefficient. Then summarized these results in a network. This network exhibits statistical features similar to previously described ecological networks of macro- and microorganisms. In network parlance it has non-random, small-world properties, i.e. highly interconnected taxa, short path length, and power law distributions of the interactions and taxa centrality as well as of taxa connectivity. Various simulations corroborated theory, that the configuration of this microbial co-occurence network could provide robustness against taxon (node) and interaction (edge) losses. Moreover, these simulations provided evidence, that taxa with a high number of co-occurrences and at intersections central to the network, represent microbial “keystone” taxa. Similar evidence is apparent for interactions at the intersections of the network as their simulated removal rapidly fragmented the network and impacted network properties. Considering issues of core ecological interest; functional redundancy, the existence of rich and abundant seed banks, and low dispersal limitations have been suggested to provide ecosystem stability for microbial communities. Here we add that the intrinsic interaction patterns, as proposed from the network properties, allow natural complex microbial systems to be highly resilient and resistant to random species removal induced by, for example, gradual environmental change or disturbances besides (or even because of) the existence of keystone taxa and intersecting interactions.

59 TUESDAY 10 SEPTEMBER 2013 OS-2B. Bacterial diversity: from community composition to community functions

14:45 OASES OF LIFE IN THE DEAD SEA

Danny Ionescu, Max Planck Institute for Marine Microbiology, Bremen (Germany) Coauthors: Haeusler S, Siebert C, Noriega B, Adeboyejo F, Dittmar T, de Beer D

The Dead Sea is a hypersaline terminal desert lake. It is a hostile environment for microorganisms because of the high concentration of divalent cations (2 M Mg2+ and 0.5 M Ca2+) as well as its high salinity (ca. 350 g l-1 total dissolved solids). The resident bacterioplankton reach <104 cells ml-1 except during, rare, strong winters when the upper water layer is diluted by up to 30%. In such occasions blooms of the green alga Dunaliella occur followed by blooms of Archaea. We have discovered oases of life in the Dead Sea in several systems of submarine freshwater springs. These systems harbor each, numerous individual springs which differ in their chemistry and morphology one from the other. We focused on two such systems in the Darga area and analyzed the diversity of the microbial community and its activity. Pyrosequencing has showed that the microbial community in the spring water differs significantly from that in the spring sediments. The composition of the latter resembles, however, that of the normal Dead Sea sediments. Areas where freshwater seeps through the sediment were covered by large biofilms of Halothiobacillus, cyanobacteria and diatoms. Using in-situ microsensor systems we were able to show microbial sulfide oxidation in these mats. Oxygenic was measured in-situ as well as ex-situ under various salinities. These measurements show the are at optimum at a salinity much lower than that of the Dead Sea. Nevertheless, they are able to actively survive a salinity range from nearly freshwater to Dead Sea water salinity. Stronger outflows where characterized by biofilm-covered cobble stones. Using a newly developed salinity microsensor we could show that the location of the biofilms on these rocks coincides with areas of reduced salinity. As predicted by the sequencing data, we were able to measure in this system sulfate reduction and ammonia oxidation. Both processes were detected up to in-situ salinities, although they were believed not to be thermodynamically feasible in the Dead Sea. In addition to a reduced salinity, a higher pH, sulfide and sulfate we suggest the springs water provide the community with a diverse composition of dissolved organic matter. High resolution mass spectrometry showed that a significant portion of the organic matter originating in the aquifers feeding the springs, does not reach the Dead Sea. The molecular composition of this organic matter fits the microbial communities found in the springs sediments. Interestingly these include anaerobic degraders of polyaromatic compounds . New data suggests that additional spring systems may occur in the Dead Sea at depths deeper than we explored by SCUBA. Thus, oases of life may not be as rare and may have a significant influence on the biogeochemistry of the Dead Sea.

60 TUESDAY 10 SEPTEMBER 2013 OS-2B. Bacterial diversity: from community composition to community functions

15:00 DENITRIFICATION IN SHALLOW AND DEEP GROUNDWATER; ACTIVITY, DIVERSITY OF CORRESPONDING COMMUNITY AND ENVIRONMENTAL FACTORS

Kenji Kato, Shizuoka University (Japan) Coauthors: Katsuyama C, Kinoshita T, Nagaosa K, Suwa Y

Denitrification is an important pass to remove nitrate from contaminated groundwater as well as an essential function in oxidation-reduction interface, which distributes widely in subsurface aquatic environment influenced by penetrating rain water as well as constrained by turn over time of the water. We studied impact of dissolved oxygen (DO) concentration and organic substrate species on denitrification activity which was measured using 15N tracer experiment and corresponding functional microbes were revealed using sequencing with nirK/nirS genes. Denitrification in various depths water ranging from 1 m to 250 m in subsurface was examined. Findings show controlling factors of denitrification in groundwater, and resultant function of denitrification which reduces oxygen-redox potential is suggested. Not glucose but acetate was an appropriate organic compound for the examined groundwater, which contained relatively high amount of acetate in the groundwater. Concerning deep aquifer in sedimentary geological setting, the groundwater at 140 m depth did not contain oxygen, had an Eh ranging from -144 to 6.8 mV, and was found to be a potential field for denitrification.

61 TUESDAY 10 SEPTEMBER 2013 OS-2B. Bacterial diversity: from community composition to community functions

15:15 DIVERSITY, ABUNDANCE, AND ACTIVITY OF CHITINOLYTIC BACTERIA IN CONTRASTING FRESHWATER LAKES

Helmut Buergmann H, Eawag: Swiss Federal Institute of Aquatic Science and Technology, Kastanienbaum (Switzerland) Coauthors: Köllner K

Chitin is an abundant biopolymer in freshwater ecosystems. Currently, little is known about the identity and ecology of freshwater chitinolytic bacteria, in spite of their key role for the hydrolysis of this compound. We characterized the diversity of potentially chitinolytic bacteria by 454 pyrosequencing of chiA amplicons from zooplankton, water, and surficial sediments of an oligotrophic and a eutrophic lake. We determined the abundance of chiA using quantitative PCR and the potential chitinolytic activity by enzyme assay. The abundant chiA sequence types were phylogenetically characterized and interpreted in the context of the bacterial community composition analyzed by 454 pyrosequencing of the 16S rRNA gene. The dominant pelagic bacteria in both lakes were Actinobacteria. However, actinobacterial chitinases were only abundant in the lake sediments and the zooplankton sample of the oligotrophic lake. The predominant chitinase in the water of the oligotrophic lake was a Stenotrophomonas maltophilia chitinase. As this sequence was not abundant in the particulate fraction, and chitinolytic activity was below detection in water samples, S. maltophilia may rather be involved in scavenging chitin hydrolysis products released to the water column. In the eutrophic lake, a single phylogenetically unidentified chitinase lineage was dominant in all three habitats. As expected chitinolytic activity was high in the sediment, but also in the zooplankton indicating that chitin degradation begins already during sedimentation through the water column. Although the total diversity of the detected chitinase sequences was striking, the bulk of chitin hydrolysis potential appeared to be associated with a few dominant species in these habitats that were however different in the studied lakes.

62 TUESDAY 10 SEPTEMBER 2013 OS-2B. Bacterial diversity: from community composition to community functions

15:30 ELUCIDATION OF MICROBIAL COMMUNITIES INVOLVED IN CO2 FIXATION IN KARSTIC LIMESTONE AQUIFERS TARGETING RUBISCO- AND AMMONIA MONOOXYGENASE ENCODING GENES

Martina Herrmann, Friedrich Schiller University Jena (Germany) Coauthors: Opitz S, Rusznyak A, Schulze I, Akob D, Totsche KU, Kuesel K

Limestone aquifers play an important role as drinking water resource, however, our knowledge of the microbial processes involved in carbon and nitrogen cycling in these environments is still limited. In oligotrophic limestone aquifers, chemolithoautotrophy may play an important role in the overall carbon flow. In this project, we investigated the CO2-fixing bacterial communities in the groundwater of a shallow, suboxic, and a deep, oxygen-rich limestone aquifer in the Hainich region (Thuringia, Germany), targeting cbbL and cbbM genes encoding RubisCO type I and II. In addition, we studied the microbial communities involved in ammonia oxidation, the first step of , targeting amoA genes encoding ammonia mono-oxygenase. The objectives of this study were (i) to follow seasonal dynamics of the CO2-fixing and the ammonia-oxidizing communities over a two years period, (ii) to analyze their diversity targeting cbbM, cbbL, and amoA genes and transcripts, and (iii) to elucidate links between autotrophy and nitrification. Results of quantitative PCR suggested that approximately 0.3 to 14 % of the groundwater bacterial population had the genetic potential to fix CO2 via the with strong seasonal fluctuations but without significant differences between the two aquifers. In contrast, the abundance of ammonia oxidizers was clearly linked to oxygen availability with significantly higher amoA gene copy numbers in the deeper aquifer. Pyrosequencing of cbbM transcripts revealed that the active CO2-fixing bacterial communities were dominated by organisms related to Sulfuricella denitrificans, Sideroxydans lithotrophicus, Acidithiobacillus ferrooxidans, and Halothiobacillus sp. in both aquifers. Analysis of cbbL genes and transcripts showed that organisms related to Nitrosomonas ureae constituted a substantial fraction of the CO2-fixing community in the deep aquifer, which was confirmed by amoA gene-based analysis. Our data provide strong evidence that chemolithoautotrophy coupled to nitrification contributes to the carbon flow in a limestone aquifer at high oxygen availability while carbon fixation appears to be primarily linked to other metabolisms involving sulphur and iron under low oxygen availability.

63 TUESDAY 10 SEPTEMBER 2013 SESSION 5. Giving and getting: lifestyles of attached and symbiotic microbes

16:15 SAME SAME BUT DIFFERENT: COMPARATIVE GENOMIC ANALYSES OF CHEMOSYNTHETIC SYMBIONTS OF MUSSELS AND THEIR FREE-LIVING SUP05 RELATIVES

Nicole Dubilier, Max Planck Institute for Marine Microbiology, Bremen (Germany)

The common perception of beneficial associations between animals and bacterial endosymbionts is that these have evolved only rarely from a few bacterial lineages that were uniquely adapted to a symbiotic lifestyle. Our recent analyses of the phylogenetic diversity of intracellular symbioses between chemosynthetic bacteria and deep-sea bathymodiolin mussels from hot vents, cold seeps and other chemosynthetic environments indicate that bathymodiolin mussels were colonized multiple times by many different lineages of bacteria (Petersen et al. 2012 Biol Bull 223: 123-137). At least four different lineages of free-living sulfur-oxidizing bacteria and six different lineages of free-living methane-oxidizing bacteria have established symbioses with bathymodiolin mussels, indicating that it may be evolutionarily "easy" to become an intracellular symbiont. To better understand the genetic attributes that enable chemosynthetic bacteria to adapt to a symbiotic lifestyle, we are currently comparing the genomes of the sulfur-oxidizing symbionts of bathymodiolin mussels with their closest free-living relatives, ubiquitous pelagic sulfur-oxidizers called SUP05 that dominate oxygen minimum zones worldwide, and have also been found in hydrothermal vent plumes (Anantharaman et al. 2013 PNAS 110: 330-335). Our analyses show that the Bathymodiolus symbiont has undergone massive rearrangements, and that as much as 38% of its genes are potentially of foreign origin. Genes and regions known to play a role in DNA transfer such as transposases and integron insertion sites are present in the Bathymodiolus symbiont and SUP05 bacteria, revealing a possible mechanism for horizontal gene transfer into these lineages. Genes of potentially foreign origin in the Bathymodiolus sulfur-oxidizing symbiont include genes for the use of hydrogen as an energy source (Petersen et al. 2011 Nature 476: 176- 180) and a highly diverse array of toxins that could be used for beneficial interactions with the host. The acquisition of these genes may have played a key role in enabling free-living sulfur- oxidizing bacteria to establish symbioses with deep-sea mussels and make optimal use of the energy sources available in their environment.

64 TUESDAY 10 SEPTEMBER 2013 SESSION 5. Giving and getting: lifestyles of attached and symbiotic microbes

16:30 METABOLICALLY ACTIVE EPIBIOTIC BACTERIA OF DAPHNIA SPP.; AN UNEXPLORED FOOD WEB SHORT CUT

Ester Eckert, Limnological Station, University of Zurich (Switzerland) Coauthors: Pernthaler J

Identifying interacting species and their mode of interaction within food webs is crucial to draw conclusions about ecosystem-level processes and stability. We analysed the activity and identity of bacterial epibionts in cultures of Daphnia galeata and in natural daphnid populations from Lake Zurich. Epibiotic bacteria incorporated considerable amounts of dissolved organic carbon (DOC), as estimated via the uptake of tritiated leucine. Three times higher incorporation rates of this tracer were observed by microbes on a single Daphnia than in one ml of lake water. However virtually no incorporation was detected if daphnids were anesthetized, suggesting that active filtration by the animals was required for microbial DOC uptake. We could assign this activity predominantly to the heterotrophic microbes that were localised on the filter combs of daphnids, where the passage of lake water would ensure a constant supply of DOC to bacteria. Fluorescence in situ hybridisation and 16S rRNA gene sequencing suggested that most of these filter comb associated bacteria were affiliated with Betaproteobacteria from the genus Limnohabitans. Specifically, we identified a monophyletic cluster that encompassed Limnohabitans planktonicus together with sequence types from D. galeata cultures, from the gut of D. magna, and from daphnids of Lake Zurich. Our results suggest that the occurrence of bacteria related to L. planktonicus on Daphnia spp. is a widespread and rather common trait, and that a large amount of newly acquired organic carbon in Daphnia is in fact not associated with the crustacean biomass itself but with epibiontic bacteria. The unexplored physical association of Daphnia spp. with heterotrophic bacteria may have considerable implication for carbon transfer within freshwater food webs. Specifically, daphnids may represent a direct trophic link between bacterial DOC uptake and predation by fish.

65 TUESDAY 10 SEPTEMBER 2013 SESSION 5. Giving and getting: lifestyles of attached and symbiotic microbes

16:45 ALGAL-BACTERIAL INTERACTIONS IN AGAR: FROM CLOSE AFFAIRS TO LONG DISTANCE RELATIONSHIPS

Ottavio Croze, University of Cambridge (UK) Coauthors: Cooper MB, Peaudecerf F, Goldstein RE, Bees MA, Smith AG

The symbiosis between algae and bacteria is often predicated on the exchange of metabolites. In particular, half of more than 300 algal species surveyed in a recent study were found to require exogenous vitamin B12 for growth. This vitamin can be obtained from symbiotic bacteria. For example, the soil bacterium Mesorhizobium loti, better known for its root nodule symbiosis with legumes, can also form a symbiosis with the freshwater green alga Lobomonas rostrata, a vitamin B12 auxotroph. M. loti can sustain the growth of L. rostrata in cultures not supplemented with B12 and, in exchange, the alga provides fixed carbon for bacterial growth. In liquid cultures, the populations of bacteria and algae form a stable equilibrium, which is disrupted by the addition of either vitamin B12 or a carbon source. When algae and bacteria are spotted at different distances from each other on hard agar (2% w/v), M. loti also supports the growth of L. rostrata, but gradients of growth have been observed across the algal colonies. Both L. rostrata and M. loti are motile by means of flagella. To investigate if the swarming motility of M. loti is the cause of the observed gradients, we repeat here the hard agar experiments, imaging bacterial and algal colonies macro- and micro-scopically. It is demonstrated that neither algae nor bacteria can swarm, but maintain a “long-distance relationship” with the algae across the agar, interacting only via metabolite diffusion (including, significantly for the algae, vitamin B12). We then discuss new experiments where the concentration of soft agar is used in capillary and plate assays to control the role of motility in symbiotic interactions, including suppression of chemotactic responses, as recently demonstrated for Escherichia coli. For example, in agar soft enough to allow normal chemotactic motility of M. loti, but hard enough to stop L. rostrata from swimming, we demonstrate how the spatio-temporal profiles of bacteria in a capillary differ in the presence and absence of carbon sources in the agar. We discuss our results in terms of the biophysics of diffusion and chemot axis, and speculate on the ecological significance of our findings for the rhizosphere and freshwater benthic zones.

66 TUESDAY 10 SEPTEMBER 2013 SESSION 5. Giving and getting: lifestyles of attached and symbiotic microbes

17:00 A BACTERIAL PATHOGEN USES DIMETHYLSULFONIOPROPIONATE AS A CUE TO TARGET HEAT-STRESSED CORALS

Melissa Garren, Massachusetts Institute of Technology (USA) Coauthors: Son K, Raina JB, Rusconi R, Menolascina F, Shapiro OH, Tout J, Bourne DG, Seymour JR, Stocker R

Diseases are an emerging threat to ocean ecosystems . Coral reefs, in particular, are experiencing worldwide decline due to disease and bleaching, which have been exacerbated by rising seawater temperatures . Yet, the ecological mechanisms behind most coral diseases remain unidentified . Here we demonstrate that a coral pathogen, Vibrio coralliilyticus, uses chemotaxis and chemokinesis to target the mucus of its coral host, Pocillopora damicornis. A primary driver of this response is the host metabolite dimethylsulfoniopropionate (DMSP), a key element in the global sulfur cycle and a potent foraging cue throughout the . Coral mucus is rich in DMSP and we found that DMSP alone elicits chemotactic responses of comparable intensity to whole mucus. Furthermore, in heat-stressed coral fragments, DMSP concentrations increased five- fold and the pathogen’s chemotactic response was correspondingly enhanced. Intriguingly, despite being a rich source of carbon and sulfur, DMSP is not metabolized by the pathogen, suggesting that it is used purely as an infochemical for host location. These results reveal a new role for DMSP in marine disease, demonstrate the importance of chemical signalling and swimming behaviour in the recruitment of pathogens to corals, and highlight the impact of increased seawater temperatures on disease pathways.

67 TUESDAY 10 SEPTEMBER 2013 SESSION 5. Giving and getting: lifestyles of attached and symbiotic microbes

17:15 CHEMOTAXIS BY CORAL-REEF BACTERIA

Jessica Tout, University of Technology, Sydney (Australia) Coauthors: Jeffries T, Petrou K, Stocker R, Ralph P, Seymour J

Microorganisms live in tight ecological associations with corals, but the behavioural mechanisms underlying these associations are not yet understood. To examine the potential role of chemotaxis in the ecology of coral reef bacterial communities, we performed a suite of laboratory and in-situ experiments. We examined the behavioural response by coral associated bacteria towards several amino acids, sugars, ammonium chloride, Symbiodinium exudates and dimethylsulfonopropionate (DMSP). Laboratory experiments involved modified syringe assays and we developed a novel microfabricated In-situ Chemotaxis Assay (ISCA) that was also deployed on Heron Island. We deployed the ISCAs in water samples associated with; (i) the surface of the coral species Acropora palifera (ii) the surface of the coral species Acropora aspera (iii) the sandy substrate within the reef and (iv) open water, outside of the reef. Strong chemotactic responses towards several chemoattractants were observed for both laboratory and in-situ studies, where coral reef- associated bacteria exhibited significantly higher levels of chemotaxis than bacteria from open water or the sandy substrate. The taxonomic composition of the microbes responding to the ISCAs was sequenced using 16S rRNA tag pyrosequencing and there was a clear partitioning between the microbial communities responding to the different chemoattractants. Metagenomes sequenced from each site supported our experimental findings by revealing that motility and chemotaxis genes were significantly more abundant in the coral microenvironments. Our results are the first to illustrate chemotaxis occurring in natural coral reef bacterial communities in-situ, and indicate that motility and chemotaxis are important phenotypes among coral associated bacterial communities.

68 WEDNESDAY 11 SEPTEMBER 2013

9:00 METATRANSCRIPTOMIC PROBING OF MICROZONES AND INTERFACES

Invited Lecture by Mary Ann Moran Department of Marine Sciences, University of Georgia (USA)

The biogeochemistry that occurs in microzones and interfaces is hard to measure with bulk approaches, since this average across microenvironments and have low sensitivity to rapidly- cycling and low concentration compounds. Bacterial gene expression patterns, however, can provide an instantaneous assessment of the ecological conditions experienced by cells, capturing the processes that are difficult to detect at the bulk level yet are important at the ecosystem, and even global, scale. We are using metatranscriptomics to explore the biogeochemistry of microzones and interfaces. These include studies of the differential activities of marine free-living versus -associated bacterial cells, and phycosphere-scale interactions between bacteria and phytoplankton.

69 WEDNESDAY 11 SEPTEMBER 2013 OS-6. Genomics for a better understanding of the aquatic biogeochemical processes

9:30 MAJOR ROLE OF PHOTOHETEROTROPHIC AND CO OXIDIZING ROSEOBACTER RCA POPULATION IN THE OCEAN

Meinhard Simon, ICBM - University of Oldenburg (Germany) Coauthors: Wemheuer B, Giebel HA, Brinkhoff T, Beardsley C, Bakenhus I, Daniel R, Voget S

The RCA (Roseobacter Clade Affiliated), with a sequence similarity of >98% of its 16S rRNA gene, is the largest cluster of the marine Roseobacter clade and most abundant in temperate to (sub)polar oceans, constituting up to 35% of total bacterioplankton. Genome and postgenomic analyses of an RCA organism, Cand. Planktomarina temperata RCA23, revealed the active performance of a novel metabolism, a triple way of energy conversion. In addition to aerobic respiration, aerobic anoxygenic photosynthesis (AAP), and CO oxidation. This organism thus exhibits a photochemolithoorganoheterotrophic life style. In order to assess the biogeochemical significance of the RCA cluster and of Cand. Planktomarina temperata RCA23 we investigated a phytoplankton spring bloom in the North Sea. The RCA cluster constituted 5.5% of the total, but 10-31% (mean 20%) of the active bacterioplankton. As shown by a metatranscriptomic analysis, the genome of Cand. Planktomarina temperata RCA23 was transcribed to 86%, including all relevant metabolic functions and AAP and CO oxidation. Hence, this abundant organism carried out its unique energy metabolism in situ. The genome of Cand. Planktomarina temperata RCA23 was also retrieved to 85% from metagenomic data sets from the Western English Channel and a Norwegian fjord and to 78% from stations of the Global Ocean Sampling (GOS) expedition in the western Atlantic. In this region, up to 6.5% of the total reads mapped on the genome of Cand. Planktomarina temperata RCA23. Hence, this abundant taxon is a major player in ocean biogeochemistry and in reducing the secondary greenhouse gas CO.

70 WEDNESDAY 11 SEPTEMBER 2013 OS-6. Genomics for a better understanding of the aquatic biogeochemical processes

9:45 BIOGEOCHEMICAL PROCESSES IN FRESHWATER SEDIMENTS: CAN THE ABUNDANCE OF MICROBIAL FUNCTIONAL GENES BE USED AS PROXY?

Anne Steenbergh, NIOO-KNAW, Wageningen (The Netherlands) Coauthors: Bosma T, Lieten S, van der Zaan B, Bodelier PLE

Sediments of freshwater systems are hotspots of microbial activity and are important for biogeochemical cycling and greenhouse gas emissions. However, the diversity and functioning of microbial communities and their link with biogeochemistry in freshwater ecosystems is highly underexplored in comparison to terrestrial and marine ecosystems. Hence, it is not clear how microbial diversity, abundance and activity are affected by environmental change, such as land- use change related to the bio-based economy. In order to gain insight into ecosystem functioning of freshwater sediments and into the relation between ecosystem functioning and the abundance of microbial genes, we have selected and sampled a reference set of 50 sediments in the Netherlands. The 50 selected sampling sites are distributed across ten areas (5 x 5 sandy soil and 5 x 5 clay soils). The sampled sites are either drainage ditches or streams, and have low salt concentrations and circumneutral pH. The 5 sites per sampling area were chosen to have a wide range of nutrient concentrations in the water layer. We have determined the microbial process rates (oxic & anoxic respiration, (de)nitrification, sulfate reduction, methane production & oxidation) and physico-chemical properties (e.g. particle size distribution, nutrient concentrations, organic matter content) of the reference set of 50 sampling sites. The microbial process rates were found to vary widely for the different sediments. The abundance of microbial functional genes in these sediments will be determined using the GeoChip, a microarray that harbors probes for more than 120.000 microbial genes. In this way, we can link the abundance of microbial functional genes to ecosystem processes. If the abundance of (sets of) microbial genes is related to ecosystem functioning, the abundance of these “indicator genes” can potentially be used as a monitoring tool to efficiently monitor the impact of human activity on functioning.

71 WEDNESDAY 11 SEPTEMBER 2013 OS-6. Genomics for a better understanding of the aquatic biogeochemical processes

10:00 STRUCTURING OF BACTERIOPLANKTON DIVERSITY AND FUNCTION IN A TROPICAL POLLUTED COASTAL BAY

Rodolfo Paranhos, Institute of Biology - Rio de Janeiro Federal University (Brasil) Coauthors: Gregoracci G, Nascimento J, Cabral A, Valentin J, Thompson C, Thompson F

Structuring of bacterioplanktonic populations and factors that determine the structuring of specific niche partitions have been demonstrated only for a limited number of colder water environments. In order to better understand the physical chemical and biological parameters that may influence bacterioplankton diversity and abundance, we examined their productivity, abundance and diversity in the second largest Brazilian tropical bay (Guanabara Bay, GB), as well as seawater physical chemical and biological parameters of GB. The inner bay location with higher nutrient input favored higher microbial (including vibrio) growth. Metagenomic analysis revealed a predominance of Gammaproteobacteria in this location, while GB locations with lower nutrient concentration favored Alphaproteobacteria and Flavobacteria. According to the subsystems (SEED) functional analysis, GB has a distinctive metabolic signature, comprising a higher number of sequences in the metabolism of phosphorus and aromatic compounds and a lower number of sequences in the photosynthesis subsystem. The apparent phosphorus limitation appears to influence the GB metagenomic signature of the three locations. Phosphorus is also one of the main factors determining changes in the abundance of planktonic vibrios, suggesting that nutrient limitation can be observed at community (metagenomic) and population levels (total prokaryote and vibrio counts).

72 WEDNESDAY 11 SEPTEMBER 2013 OS-6. Genomics for a better understanding of the aquatic biogeochemical processes

10:15 INSIGHTS INTO THE UNCULTURED MARINE ZETAPROTEOBACTERIA THROUGH THE USE OF SINGLE CELL GENOMICS AT LOIHI SEAMOUNT, HAWAII

Erin Field, Bigelow Laboratory for Ocean Sciences, East Boothbay (USA) Coauthors: Lyman A, Stepanauskas S, Emerson D

The Zetaproteobacteria are a candidate class of Proteobacteria typically found in high iron marine environments where they can be the predominant microbial group. There are currently only a few cultured representatives that are all related to Mariprofundus ferrooxydans strain PV-1, an obligate chemolithoautotrophic iron-oxidizer that grows under microaerobic conditions and forms a mineralized stalk. Previous studies have demonstrated that the Zetaproteobacteria are more phylogenetically diverse than the cultured representatives suggest. Unfortunately, the Zetaproteobacteria remain difficult to grow in the lab so culture-independent methods, such as single cell genomics, offer a powerful way to evaluate their role in marine environments. The Zetaproteobacteria have been found at a variety of Fe(II)-rich hydrothermal vent sites, both deep and shallow, in the world’s oceans; however they have been most well-studied at Loihi Seamount, Hawaii, USA where they can account for over 50% of the total microbial population. Iron mat samples from various sites at Loihi Seamount were sorted and classified based on 16S rRNA gene analysis. Phylogenetically diverse Zetaproteobacteria were targeted for whole genome sequencing. To date, we have obtained 19 Zetaproteobacteria single amplified genomes (SAGs) from 6 different OTUs. Comparative genomics of these SAGs provides us insight into the potential metabolic role of these organisms in their environment including their potential for iron oxidation, carbon fixation and other processes. In addition, they have been compared to the cultured representatives, also isolated from Loihi Seamount, to better understand how representative the cultures truly are for this group. Results suggest significant differences between the cultured representatives and SAGs as well as differences in potential for iron oxidation, carbon fixation and nitrogen utilization. These analyses will significantly improve our knowledge of Zetaproteobacteria and the role they play in biogeochemical processes in marine environments.

73 WEDNESDAY 11 SEPTEMBER 2013 OS-6. Genomics for a better understanding of the aquatic biogeochemical processes

10:30 RECONSTRUCTING THE PROKARYOTIC META-OME ALONG THE AMAZON CONTINUUM

Brandon Satinsky, University of Georgia, Athens (USA) Coauthors: Crump B, Smith C, Sharma S, Zielinski B, Doherty M, Paul J, Yager P, Moran MA

The Amazon River is the world’s largest in terms of volume and area, generating a fluvial export that accounts for 18% of riverine input into the ocean, and supporting the formation of a surface plume that covers ~20% of the Western Tropical North Atlantic Ocean. Within this river-ocean continuum, microorganisms experience changing environmental conditions and heterogeneous habitats, and understanding differences in microbial processes and community structure within these habitats is critical to understanding the biogeochemistry of the system. We used meta-omics methods with the addition of internal standards to provide the first quantitative inventory of genes and transcripts in both the free-living (0.2 µm to 2.0 µm) and particle-associated (>2.0 µm) prokaryotic communities of the Amazon Continuum. Differences in -omics inventories were evident between size fractions at a given site as well as spatially along the continuum. For example, a liter of near-shore Amazon Plume seawater contained ~1 x 1011 prokaryotic gene copies and ~5 x 1011 transcripts in total, but within that liter of water, free-living cells accounted for 68% of the gene copies and 49% of the transcripts. Expression ratios (transcripts L-1/gene copies L-1) were calculated for a wide range of biogeochemically relevant genes at both the community and individual taxon scale. In near-shore Amazon Plume water, for example, free-living prokaryotes had an overall expression ratio less than half that of particle-associated prokaryotes, while large eukaryotic cells had the highest expression ratios (up to 10-fold greater than prokaryotes). With more than 1 billion paired-end metagenomic and metatranscriptomic reads obtained from two size fractions at 12 stations from the Amazon River and Plume, this dataset is one of the most detailed inventories of microbial mRNAs and genes for any aquatic environment. Linking gene expression profiles of the active bacteria within the river and plume to measures of ongoing microbial and biogeochemical processes will improve our understanding of the metabolic roles of the prokaryotic community and their contributions to the biogeochemistry of the system.

74 WEDNESDAY 11 SEPTEMBER 2013 OS-S1. Ecology of waterborne pathogens in the light of climate change

11:15 THE ENVIRONMENT REVEALS CRYPTIC INTERACTIONS BETWEEN AND HOST IMMUNITY

K. Mathias Wegner, AWI Waddenseastation Sylt, List (Germany) Coauthors: Wendling C, Lokmer A, Eiler A, Peter H, Volkenborn N

The interactions between the resident microbiome associated with host tissues are highly complex and often the environment determines the life-style role of resident bacterial strains. A change of the environment as projected in global change scenarios can for example change neutral commensals to harmful pathogens or beneficial mutualists. Therefore, also the selective pressures governing the coevolutionary trajectory can change with the environment. Here, we used two genetically distinct invasions of Pacific oysters Crassostrea gigas to test whether adaptation to local commensal strains of Vibrio splendidus show such environment specific coevolutionary trajectories. We can show that microbial communities are stable over time and assemble in a genotype specific manner fullfilling necessary prerequesites for coevolution. A change of the environment however disrupts such associations and we found that a promotion of growth of local strains at ambient temperatures, where selection coefficients for the host are low, is reversed at elevated temperatures, where selection on the host is high. We can therefore conclude that the environment is a major determinant of coevolutionary patterns and that local adaptation can depend on the selective gradients observed in nature.

75 WEDNESDAY 11 SEPTEMBER 2013 OS-S1. Ecology of waterborne pathogens in the light of climate change

11:30 THE TRANSMISSION CYCLE OF F. TULARENSIS HOLARCTICA, THE ETIOLOGICAL AGENT OF TULAREMIA, ORIGINATES IN IN THE AQUATIC HABITAT OF THE MOSQUITO VECTOR - POTENTIAL FOR CLIMATE EFFECT ON OUTBREAK DYNAMICS

Johanna Thelaus, Swedish Defence Research Agency, Umeå (Sweden) Coauthors: Bäckman S, Andersson AC, Akfur C, Lundmark E, Granberg M, Näslund J

Outbreaks of tularemia in Sweden, caused by the bacterium Francisella tularensis holarctica (F. t. holarctica), are associated with natural waters and mosquito vectors. A model using geographical, meteorological and hydrological data to predict the abundance of mosquitoes in Sweden has shown that the peak of mosquitoes correlates with rainfall and precede the onset of human cases of tularemia. Thus, change of climate may influence the outbreaks dynamics of tularemia. Using molecular methods, F. t. holarctica has been shown to persist in aquatic environments for prolonged periods probably in association to protozoa. Thus, it is hypothesized that the reservoir for the bacteria could be identified in nutrient rich waters with intense protozoan predation. A limitation for further studies of the bacterium in these aquatic environments is that F. t. holarctica, soon after inoculation, are considered to enter a state of viable but not culturable. The clinical relevance of the aquatic F. t. holarctica and the dynamics of tularemia outbreaks are unclear. We aim to investigate the role of nutrient rich natural waters as a potential reservoir for tularemia outbreaks and more specifically to evaluate the hypothesis that mosquito larvae exposed to the bacterium in their aquatic larval stage, as adult mosquitoes, transmit disease to susceptible hosts (i.e. transstadial maintenance). Using a fully virulent F. t. holarctica strain and mosquito Aedes aegypti we show transstadial maintenance of the pathogenic bacterium throughout mosquito development. Intraperitoneal injection of extracts from the mosquitoes exposed to F. t. holarctica as larvae resulted in that mice acquired tularemia. Our results imply the possibility of a transmission-cycle originating in the aquatic habitat of the mosquito vector, to our knowledge a unique transmission cycle for a bacterial pathogen. Thus, parameters likely to be affected by climate change i.e. productivity and rainfall; is also likely to influence the availability of breeding grounds for mosquito vector as well as the environmental fate of the pathogenic bacterium F. t. holarctica (i.e. microbial food web dynamics). Increased understanding of the ecology of vector and waterborne pathogens is needed in order to perform informed microbial risk assessments and predict the long term consequences of outbreaks or antagonistic use.

76 WEDNESDAY 11 SEPTEMBER 2013 OS-S1. Ecology of waterborne pathogens in the light of climate change

11:45 LEGIONELLA - PROTOZOA INTERACTIONS AND CLIMATE CHANGE: IMPACT ON PREVALENCE AND RESERVOIRS OF PATHOGENIC STRAINS

René Lesnik, Helmholtz Centre for Infection Research, Braunschweig (Germany) Coauthors: Pecellin M, Brettar I, Höfle M

The bacterial genus Legionella comprises the most prevalent waterborne pathogens in developed countries. In Europe, incidences of Legionella infections (Legionellosis) increased recently and distinct seasonal patterns peaking in late summer are observed every year. Therefore, climate change can be considered a threat to human health causing increased Legionellosis. Thus, higher temperatures of source water and drinking water supply systems (DWSS) are expected to have a major impact on the prevalence of pathogenic Legionella species. All Legionella replicate intracellularly in protozoan hosts, e.g. amoebae, their presence might determine the prevalence and virulence of Legionella species. Therefore, increase of temperature might promote the survival of mesophilic Legionella species directly and/or indirectly by promoting the survival of their specific protozoan host. The structure of Legionella communities and protozoan communities in water and biofilm of different DWSS habitats along a temperature gradient have been analysed and compared covering a broad climatic range from cool-temperate to Mediterranean climate. Species composition of drinking water communities comprising analysis of all Legionella species and protozoa as well as their seasonal dynamics were analysed using molecular fingerprints based on the 16S rRNA gene and the 18S rRNA gene, respectively. In addition, with respect to L. pneumophila, the samples were analysed on the serogroup (Sg)- and clonal-level including quantification by real-time PCR and a high-resolution genotyping analysis by Multi-Locus-Variable- Number-of-Tandem-Repeats (MLVA). The results elucidate the relationship between Legionella species and protozoa present in DWSS as well as the effect that temperature has on both taxa. Furthermore, the influence of Legionella species, protozoan hosts and temperature regime on the abundance of highly pathogenic L. pneumophila strains (Sg1, MLVA analyses) was analysed. The potential impact of temperature changes as expected due to climate change on the prevalence and reservoirs of Legionella and conceivable prevention measures such as construction of wetlands and river basin management will be discussed.

77 WEDNESDAY 11 SEPTEMBER 2013 OS-S1. Ecology of waterborne pathogens in the light of climate change

12:00 VIBRIO SPP. IN THE EASTERN ENGLISH CHANNEL-NORTH SEA (FRANCE) : OCCURRENCE OF HUMAN AND ANIMAL PATHOGENIC STRAINS AND EVOLUTION OF THE CULTURABLE POPULATION STRUCTURE IN A CHANGING ENVIRONMENT

Aurélie Touron-Bodilis, EDF Research and Development, Chatou (France) Coauthors: Tall A, Antajan E, Boisset C, Delesmont R, Hervio-Heath D

In Europe, the number of cases of Vibrio-associated infectious diseases reported annually is quite low, but the risk is expected to increase due to raw shellfish consumption, increase of immuno- compromised people, impact of anthropogenic activities and global warming on the marine environment. In France, the majority of the vibriosis cases (130 of 134) reported between 1995 and 2009 (Institut Pasteur, Paris) was caused by V. cholerae non-O1/non-O139 (51, 5% of the cases among which 45% were contracted abroad), V. alginolyticus (18.6%), V. parahaemolyticus (17%), or V. vulnificus (9.7%). The presence of potentially pathogenic Vibrio spp. for humans was reported in French coastal waters but little is known about the ecology and virulence of these species, and even less about species pathogenic to marine animals. To better understand the ecology and natural diversity of Vibrio spp. and particularly of pathogenic species, a study was conducted from May 2009 to September 2011 in water and superficial sediments in the Eastern Channel-North Sea (France). Simultaneously to in situ measurement of physico-chemical and biological parameters, more than 4000 strains of vibrios have been isolated on TCBS medium at 37°C and 22°C. The vast majority of the 37°C-isolates (9 campaigns) was identified by qPCR (Vibrio spp., V. alginolyticus, V. parahaemolyticus, V. vulnificus, V. cholerae and V. harveyi), whereas partial sequencing of pyrH and toxR genes was required to identify the diversity of environmental isolates at 22°C (2 campaigns). Among the 37°C isolates (10 species identified), pathogenic species for humans were rarely detected and V. harveyi-related species represented the major group, with the predominance of V. alginolyticus (> 55%) and V. harveyi (> 10%). An important diversity of species among the 22°C-isolates was highlighted (23 species), dominated by the V. splendidus- related species (> 80%), with different predominant species depending on the season (V. splendidus in winter and V. celticus in late summer). Moreover, the abundances of these two culturable populations presented different seasonal dynamics, as the seawater temperature and the zooplankton abundance showed to be the main drivers for the 37°C population, and the chlorophyll a concentration and zooplankton abundance for the 22°C population. In this environmental study, strong modifications of the culturable Vibrio spp. population structure and abundance were observed in contrasted environmental conditions, supporting the need to further study the interactions between ecological drivers involved in the seasonality and the diversity of human and animal pathogenic Vibrio species.

78 WEDNESDAY 11 SEPTEMBER 2013 OS-S1. Ecology of waterborne pathogens in the light of climate change

12:15 FIELD STUDY OF THE ECOLOGY OF VIBRIO CHOLERAE IN THE AQUATIC ENVIRONMENT OF RURAL BANGLADESH

Lorenzo Righetto, Polytechnic University of Milan (Italy) Coauthors: Zaman R, Mahmud ZH, Bertuzzo E, Mari L, Casagrandi R, Gatto M, Islam MS, Rinaldo A, Blokesch M

Presence of Vibrio cholerae serogroups O1 and O139 in the waters of the rural area of Matlab, Bangladesh was investigated by quantitative measurements carried out using a portable flow cytometer. The relevance of this work relates to the testing of a field-adapted measurement protocol that might prove useful for cholera epidemic controls. Water samples were collected from different water bodies that constitute the hydrologic system of the region, a well-known endemic area for cholera. Water was retrieved from , river waters, and irrigation canals during an inter-epidemic time period. Each sample was filtered and analyzed with a flow cytometer for a fast determination of V. cholerae cells contained in those environments. More specifically, samples were treated with O1- and O139-specific antibody, which allowed precise flow-cytometry-based concentration measurements. Using this approach we showed that both serogroups were present in the environmental waters with a consistent dominance of V. cholerae O1. Furthermore, our results confirm that specific ponds host a population of vibrios, which is able to self-sustain even when cholera cases are scarce. Such contaminated ponds may constitute a natural reservoir for endemicity in the Matlab region. We also measure the total living cell concentration as well as environmental abiotic parameters, to test whether there is any correlation with the Vibrio concentration. Contextually, results of a long-term monitoring campaign will be shown. The water level in one of the ponds that constitute the common water reservoir for human settlements in that area has been monitored between May 2011 and December 2012. Together with water volume, other relevant hydro-climatological variables were measured, such as rainfall and solar radiation. Concurrently, samples of the water were withdrawn biweekly from the and they were analyzed for phytoplankton and V. cholerae concentrations. A combination of hydrological and ecological dynamics is shown to be responsible for the observed patterns of the monitored populations. The dynamics of the water volume in the reservoir are then reconstructed as a balance of input (from rainfall and drainage) and output (evaporation) terms. Finally, a process-based model of the ecology of the bacterium is proposed, in conjunction with the dynamics of phytoplankton and of the nutrient content of the water, which fluctuates according to the balance equation previously identified.

79 WEDNESDAY 11 SEPTEMBER 2013 OS-S1. Ecology of waterborne pathogens in the light of climate change

12:30 FEMS AND SAME: SUPPORT AND OPPORTUNITIES

Pre-Lunch Talk by Daniele Daffonchio, University of Milan (Italy)

80 THURSDAY 12 SEPTEMBER 2013

9:00 PATTERNS OF MICROBE ABUNDANCE AND DIVERSITY IN THE DEEP OCEAN: THE CIRCUMNAVIGATION CRUISE MALASPINA-2010

Invited Lecture by Josep M. Gasol Aquatic Microbial Ecology Group, CSIC Institute of Marine Sciences - Barcelona (Spain) Coauthors: Salazar G, Gomes A, Pernice M, Cornejo-Castillo FM, Borrull E, Diez-Vives C, Forn I, García FC, Hernando V, Lara E, Reche I, Sarmento H, Sintes E, Teira E, Arrieta JM, Vaqué D, Massana R, Morán XAG, Duarte CM, Acinas SG

During a global circumnavigation cruise (Malaspina-2010) held between November 2010 and July 2011 we had the opportunity to sample the deep waters of the North and South Atlantic, North and South Pacific, and Indian Oceans. We measured vertical profiles of microbe abundance and heterotrophic activity, and we studied specifically the distribution of microbial diversity at the depth of ca. 4000 m all through the studied oceans by means of ARISA and 16S-DNA Illumina tags (iTags). Two fractions were considered: <0.8 µm and >0.8 and <20 µm. We describe here the variability around the characteristic depth decline of microbial abundance and activity, with clear variations in different oceans and high microbe abundance and activity in waters near the equatorial upwelling of the Pacific Ocean. We also describe a large variability in microbial characteristics at this specific depth, in which we could also enumerate heterotrophic nanoflagellates by flow cytometry to be in the 5-40 cells ml-1 range. We explore the factors determining microbe abundance in the deep. Free-living deep ocean prokaryotic communities had a greater richness (number of 97% similarity OTUs) and diversity (Shannon and Chao diversity estimators) than particle-attached counterparts. Individual samples had comparable richness values to those found in surface communities (ranging from more than 300 to less than 1000 OTUs at the sequencing effort of 9800 reads/sample). On the contrary the overall richness of the dataset (accumulating all the samples) was very low (less than 4000 OTUs at the same sequencing effort) indicating that deep ocean prokaryotic communities are highly homogeneous and many OTUs are shared between different samples. Particle-attached and free-living prokaryotes were seen to highly differ in community composition. Specific prokaryotic phyla were detected to be consistently enriched in both size-fractions indicating that particle association is a life-style conserved at broad phylogenetic scales. Besides the size-fraction effect (i.e. within each set of samples belonging to the same size fraction), the geographical distance between locations arises as the main factor explaining community compositional differences, pointing out that dispersal limitation has probably played a key role structuring prokaryotic communities in the deep ocean.

81 THURSDAY 12 SEPTEMBER 2013 OS-7. What omics can (and can't) tell us about microbial ecology

9:30 COMPARATIVE METATRANSCRIPTOMICS IDENTIFY TAXONOMIC DEPENDENT STRATEGIES FOR BACTERIAL METABOLIC FUNCTIONS DURING PHYTOPLANKTON BLOOM SENESCENCE

Daniel Lundin, KTH Royal Institute of Technology, Stockholm (Sweden) Coauthors: Akram N, Svensson L, Palovaara J, Baltar F, Vila-Costa M, Calvo E, Pelejero C, Marrasé C, González MJ, Gasol JM, Pinhassi J

Phytoplankton blooms occur in costal upwelling zones worldwide and seasonally in temperate waters where they give rise to a dynamic succession of bacterial populations. Yet, information about how bacteria process organic matter and nutrients produced by phytoplankton and about which specific genes that may be of importance is scarce. This precludes a thorough mechanistic understanding of how biogeochemical processes are regulated and of what factors that contribute to structuring of bacterioplankton communities. We carried out a phytoplankton bloom mesocosm experiment in the NW Mediterranean, and used mRNA sequencing to identify what metabolic functions were actively expressed during the initial decay phase of the bloom. Both 16S rDNA and mRNA based taxonomic profiling showed that the bacterial communities were dominated by Proteobacteria (83% and 62%) and Bacteroidetes (13% and 36%) in control and bloom samples, respectively. Metatranscriptome analyses showed that the TonB dependent receptor represented 11% (control) and 23% (bloom) of all assigned reads, suggesting that the regulation of substrate transport across the outer membrane plays an underestimated role in determining the fate of organic matter degradation. A differential expression analyses was performed on the total community transcript data set as well as on datasets on particular taxa. A total of 309 distinct genes were differentially expressed. 192 of these genes were elevated in the bloom samples and included ammonium transporters and genes involved in central carbohydrate metabolism such as aldehyde dehydrogenase and alanine dehydrogenase. Expression profiles for the three main taxa, the Alteromonadaceae, the Roseobacter clade and Flavobacteria, revealed taxa-specific trends. Roseobacters expressed 28 different genes related to sulphur metabolism (7- 9 genes for the other bacteria), but no genes for the TonB receptor. TonB receptors affiliated with Flavobacteria were 10 times higher in the bloom samples and the transcriptional profile also shows that Flavobacteria have a high metabolic rate in response to bloom decay. In contrast, in Alteromonadaceae transcript levels are relatively similar in bloom and controls. Further more, the 16S data show that abundance of Alteromonadaceae is 20% lower in bloom mesocosms. Taken together this suggests that the capability of Flavobacteria to respond to the decay phase of a bloom, may be associated with their ability to thrive during these conditions.

82 THURSDAY 12 SEPTEMBER 2013 OS-7. What omics can (and can't) tell us about microbial ecology

9:45 PREVALENT GENOME STREAMLINING AND LATITUDINAL DIVERGENCE OF MARINE BACTERIA IN THE SURFACE OCEAN

Brandon Swan, Bigelow Laboratory for Ocean Sciences, East Boothbay (USA) Coauthors: Tupper B, Sczyrba A, Lauro FM, Martinez-Garcia M, González JM, Luo H, Wright JJ, Landry ZC, Hanson NW, Thompson BP, Poulton NJ, Schwientek P, Acinas SG, Giovannoni SJ, Moran MA, Hallam SJ, Cavicchioli R, Woyke T, Stepanauskas R

Oligotrophs, slow-growing bacteria that thrive in resource-limited environments, have proven particularly difficult to cultivate and are underrepresented among existing marine cultures. By employing large-scale single cell genomics, we obtained the first insights into the genome content and global biogeography of many uncultured marine bacterial lineages inhabiting the of the nutrient-limited ocean. We found single cell genomes to be small, contained fewer duplicated genes, and displayed depletion in GC content, non-coding nucleotides, and genes encoding transcription, signal transduction, and non-cytoplasmic proteins. Notably, these genomic differences discriminated single cell genomes from their cultivated close relatives, indicating a potentially significant bias in genomic information obtained from existing representative cultures. Our data also suggests the global distribution of diverse bacterioplankton genotypes correlates with water temperature and latitude, and single cell genomes with highly similar 16S rRNA gene sequences exhibited significant genomic and biogeographic variability, highlighting challenges in the interpretation of individual gene surveys and metagenome assemblies in environmental microbiology. Our study demonstrates the utility of single cell genomics and population genetics as a pathway for improved understanding of the composition and dynamics of natural microbial assemblages.

83 THURSDAY 12 SEPTEMBER 2013 OS-7. What omics can (and can't) tell us about microbial ecology

10:00 A HOLISTIC VIEW ON MICROBIAL METAGENOMICS DATA

Emilio O. Casamayor, CSIC - Spanish Council for Research, Blanes (Spain) Coauthors: Fernàndez-Guerra A, Barberán A, Kottmann R, Glöckner FO, Bohannan B

A more complete understanding of microbial processes and patterns is essential to understand ecosystem functions and to predict the Earth’s response to global change. Community genomics is revealing an unprecedented level of microbial diversity and metabolic novelty, and is the most comprehensive approach currently used to study microbial processes and patterns in nature. Metagenomics is challenging the scientific community with an astonishing amount of complex data that intersect the disciplines of microbiology, genetics, ecology, and bioinformatics. The rate of information collection generated by metagenomics is, however, uncoupled with its ecological interpretation, and despite recent computational advances, the analysis of community genomics data within a meaningful ecological framework remains an elusive goal. To face up to this scenario, we aimed (i) to develop taxonomic and functional analysis of microbial metagenomic data in a rigorous ecological framework, (ii) to generate theoretical and analytical tools that could unveil microbial community patterns and the processes that underlie them, and (iii) to provide insights into community ecology beyond purely descriptive studies. Large metagenomic environmental surveys, like the Global Ocean Survey (GOS), offer enough genetic data to initiate the exploration of more holistic approaches on the ecology of aquatic microbial communities. In this presentation, we will show two examples recently carried out using the GOS metagenomics survey as a model dataset. On the one hand, we have applied new analytical approaches based on functional trait-based ecology (Barberan et al. 2012 Mol Ecol 21:1909-1917). On the other hand, we have explored through a novel integrative approach, missing links in aquatic microbial processes and the universe of genes of unknown functions present in any metagenomic survey, combining the knowledge on the known protein domain families and 16S ribosomal DNA with the putative coding sequences without any hint of potential function. New associations in biological processes among known protein families and between known protein families and the unknowns were observed (Fernandez-Guerra et al. Plos Biol submitted). These results, and other recent examples from the literature, show that a synergy between ecology and metagenomics may offer new perspectives and powerful posibilities for a new step forward in microbial ecology.

84 THURSDAY 12 SEPTEMBER 2013 OS-7. What omics can (and can't) tell us about microbial ecology

10:15 THE TRANSCRIPTIONAL RESPONSE OF PROKARYOTES TO THE ADDITION OF PHYTOPLANKTON-DERIVED DOM IN SEAWATER

Sara Beier, Banyuls Oceanological Observatory, LOMIC, Banyuls sur Mer (France) Coauthors: Rivers AR, Moran MA, Obernosterer I

Dissolved organic matter (DOM) from phytoplankton induces functional responses in prokaryotes that have important biogeochemical consequences. To better understand this process, we investigated the transcriptional response of a natural prokaryotic community grown on seawater amended with DOM derived from diatoms and cyanobacteria over 5 generation times in continuous cultures. Metatrascriptomic reads were classified taxonomically (by genomic binning) and functionally (using KEGG), and the regulatory behavior of individual strains (genome bins) was compared to the total community response. Our results indicate that one metabolic strategy, suggestive of generalist behavior, involved bacteria that efficiently regulated the expression of only a few genes within the total genome. There was evidence for predictable coupling between bacterial taxonomy and function. On the other hand, a more pronounced functional response in the transcriptome of individual strains compared to that in the combined metatranscriptome suggests some functional redundancy within the bacterial community. Pathways involved in carbohydrate and lipid metabolism displayed a pronounced reaction to the addition of phytoplankton-derived DOM, while those representing amino acid and nucleotide metabolism showed variable responses. The two different phytoplankton-derived DOM sources induced similar functional responses in the bacterial community transcriptome.

85 THURSDAY 12 SEPTEMBER 2013 OS-7. What omics can (and can't) tell us about microbial ecology

10:30 WHAT MAKES A BACTERIUM FRESH: COMPARISON OF FRESHWATER AND MARINE SAR11 USING SINGLE CELL GENOMICS

Stefan Bertilsson, Dept. of Ecology & Genetics - Uppsala University (Sweden) Coauthors: Andersson S, Eiler A, Fernandez-Vidal L, Garcia M, Malmstrom R, McMahon K, Stepanauskas R, Zaremba K

Members of the SAR11 clade are ubiquitous in aquatic environments and often account for a large portion of the total bacteria in planktonic environments. In the freshwater biome, SAR11 is represented by the less studied sibling-group LD12. Ribosomal RNA gene surveys have revealed strict geographical separation of the two groups with salinity as the decisive structuring environmental factor. Here we present data from a genome-wide comparison of marine SAR11 and freshwater LD12 to identify microbial adaptations to life at high and low salinity. There are so far no cultured or sequenced representatives for LD12, but several representatives for the marine SAR11 have been genome sequenced. We sorted single bacterial cells from oligotrophic, mesotrophic and eutrophic lakes and subsequently amplified their genomes with multiple displacement amplification. After 16S rRNA-based identification, ten LD12 single amplified genomes were genome sequenced and annotated. The partial genome assemblies for each of the single amplified genomes ranged in size from 0.33-0.93 Mb and feature GC content below 30% and streamlining. The freshwater LD12 pangenome reconstructed from the single amplified genomes share a majority of the genes with marine SAR11, but > 100 COGs were unique to either the freshwater or marine clade. One of the most striking differences in functional properties, as represented by protein coding genes, are contrasting sets of transporters, where marine SAR11 feature many more ABC-type and Na+ driven transporters for monomeric organic compounds. Differences were also observed in the central metabolism including the glycolysis, glyoxylate cycle and amino acid metabolism. These and other differences will be discussed to illustrate the functional traits that make a bacterium “fresh” or “salty”.

86 THURSDAY 12 SEPTEMBER 2013 OS-8A. Bacterial biogeography and dispersal in a changing world

11:15 SUCCESSION OF THE PROKARYOTIC COMMUNITY IN THE NORTH ATLANTIC’S DEEP WATER MASSES

Alexander H Frank, Department for Limnology and Oceanography, University of Vienna (Austria) Coauthors: Garcia JA, Herndl GJ, Reinthaler T

The horizontal and vertical changes of bacterial and archaeal community composition and beta- diversity were determined in the eastern North Atlantic’s dark realm. Following a 3000 km long latitudinal transect (49°N-26°N), the North Atlantic Drift province and the Gyre province were sampled from the base of the euphotic layer to the abyssopelagic realm. We used tag encoded FLX amplicon pyrosequencing with primer sets targeting the V1-V3 region to obtain ~1500 sequences per sample of an average read length of ~370 bp. Microbial beta-diversity was assessed using several estimators. Microbial diversity in the mesopelagic water masses was variable, reflecting three different biogeographic provinces of the North Atlantic, namely the drift, the subtropical, and tropical region. In the bathypelagic waters, however, microbial community composition clustered according to water masses and a clear succession of the major microbial groups was found from the north toward the south of the transect. Taken together, our data suggest that in surface waters, the prokaryotic community composition follows the Longhurst biogeographic provinces while in bathypelagic waters, it gradually changes due to the aging of the deep water masses.

87 THURSDAY 12 SEPTEMBER 2013 OS-8A. Bacterial biogeography and dispersal in a changing world

11:30 LINKAGE OF BROAD BACTERIAL TAXA TO ENVIRONMENTAL CONDITIONS AND NOT TO WATER MASS IN THE SARGASSO SEA

Johanna Sjöstedt, Linnaeus University, Kalmar (Sweden) Coauthors: Martiny JBH, Munk P, Riemann L

To explore the potential linkage between distribution of marine bacterioplankton groups, environmental conditions, and water mass, we quantified the abundance of specific bacterial taxa across the hydrographically diverse Subtropical Convergence Zone in the Sargasso Sea. Based on information from 16S rRNA gene clone libraries from different locations and depths, abundances of the predominant taxa (Eubacteria, Alphaproteobacteria, Gammaproteobacteria, Bacteroidetes, the Roseobacter, SAR11 and SAR86 clades) were quantified by Real-Time PCR. In addition, the abundances of Synechococcus, Prochlorococcus and picoalgae were determined by flow cytometry. Linear multiple regression models determining the relative effects of eight environmental variables and of water mass explained 39-83 % of the variation in abundance of the quantified taxa, although only one to three variables at a time were significantly related to any taxon’s abundance. Most of the variation in abundances was explained by depth and chlorophyll a. The predominant phototrophs, Prochlorococcus and picoalgae, were negatively correlated with phosphate while the abundances of heterotrophic bacteria were not related to nutrients. Water mass was only correlated to the abundance of the Roseobacter clade and explained 18% of the variation. Probably water mass represents one or several important variables, which were not included in the regression model. Our general finding that a large part of the variation in the abundance of broad bacterioplankton groups in the Sargasso Sea can be described by relatively few environmental parameters suggests that even relatively coarse community analyses may be useful for biogeochemically relevant predictions.

88 THURSDAY 12 SEPTEMBER 2013 OS-8A. Bacterial biogeography and dispersal in a changing world

11:45 BACTERIOPLANKTON COMPOSITION, ACTIVITY AND FATE ALONG A RIVER NETWORK: A WHOLE SYSTEM MASS BALANCE

Andrea Butturini, Department of Ecology - University of Barcelona (Spain) Coauthors: Ejarque E, Freixa A, Batani G, Guarch Ribot A, Amalfitano S, Fazi S, Romaní AM

Fluvial waters experience profound hydrological and biogeochemical changes in their downriver movement, owing to inputs (diffuse and tributaries) of natural and/or anthropogenic origin with varying in-river processes and fluvial geo-morphological assemblages. In this context, the bacterioplankton abundance is expected to increase in its downriver propagation. However, little is known on how the bacterial community readjusts its structure and functioning to these spatial hydro-biogeochemical changes. To address this gap, a river network (60 km long) has been intensively sampled under basal discharge conditions. The sampling allows executing a whole system input-output mass balance in term of hydrology (discharge, water turnover rate, water mass), biogeochemistry (nitrogen, phosphorous and organic carbon fluxes) and planktonic bacteria, described in terms of abundance (flow cytometry), community composition (CARD-FISH) and metabolic functioning (exoenzymatic activities). This approach allows discerning fluvial segments at which the bacterioplankton structure and functioning is more sensitive to in-river processes rather than punctual influences from tributaries.

89 THURSDAY 12 SEPTEMBER 2013 OS-8A. Bacterial biogeography and dispersal in a changing world

12:00 SMALL-SCALE VARIATION IN BACTERIAL COMMUNITY STRUCTURE AND FUNCTION WITHIN FRESHWATER PONDS

Gavin Lear, University of Auckland (New Zealand) Coauthors: Bellamy J, Buckley H, Case B

The extent to which bacterial communities exhibit small-scale biogeographic patterns in their distribution and function remains unclear, particularly within highly mixed freshwater environments. In this study, we investigate small-scale variability in bacterial community structure and function within a patchwork of shallow alpine tarns. Using a grid-based sampling design, we collected 100+ water samples located between 4 and 60 m apart in each pond. For every sample, variability in bacterial community structure was monitored using a DNA-fingerprinting methodology (ARISA) whereas differences in bacterial community function (i.e. carbon substrate utilisation patterns) were recorded from Biolog Ecoplates. The exact spatial location and dominant physico-chemical conditions (e.g., pH, water temperature, depth) were simultaneously recorded from every sample location. Results of multivariate Mantel correlograms showed that, on average, bacterial community structure and function became significantly different comparing samples located 20 m or more apart. Variance partitioning revealed that purely spatial variation accounted for the more of the observed variability in both bacterial community structure and function (Range: 24-38% and 17-39%) than the combination of purely environmental variation and spatially structured environmental variation (Range: 17-32% and 15-20%). Contour plots of bacterial community similarity revealed greater spatial structuring in bacterial community structure than function suggesting that some of the changes in bacterial community structure are functionally “redundant”. Our investigation, which appears to be one of the smallest scale studies of bacterial biogeography conducted within lentic freshwater, reveals the presence of distinct bacterial communities across unexpectedly small spatial scales. We suggest that even within relatively mixed ponds, bacterial communities separated by distances of <20 m may be dispersal limited, differentiating at a rate which is faster than they are mixed together due to ecological drift. Our findings also suggest that most current sampling strategies collect samples at an inappropriate scale, overlooking significant spatially structured variability in freshwater bacterial community structure and function.

90 THURSDAY 12 SEPTEMBER 2013 OS-8A. Bacterial biogeography and dispersal in a changing world

12:15 THERMOPHILIC ENDOSPORES AS MODELS FOR QUANTIFYING THE ROLE OF DISPERSAL IN

China Hanson, School of Engineering and Geosciences, Newcastle University (UK) Coauthors: Martiny J, Müller A, Loy A, de Rezende JR, Jorgensen BB, Hubert C

Microbial biogeography results from a complex interaction of ecological and evolutionary processes including environmental selection, dispersal, mutation, and drift. While selective mechanisms appear to be universally important in shaping the distribution of diverse microbes from a wide range of habitats, questions surrounding the importance of dispersal remain at the forefront of the microbial biogeography debate. This is due in part to assumptions that microbes are inherently not dispersal limited, but also because of difficulties in the ability to directly measure microbial dispersal rates and vectors. In principle dispersal can be addressed explicitly by investigating microbial distributions in the absence of selective mechanisms, but this is often difficult in natural systems where it is impossible to control for all of the external factors collectively contributing to environmental selection. Dormant endospores of thermophilic Firmicutes found in cold Arctic sediments offer a unique opportunity in this respect. Because they are capable of persisting in an inactive and resistant state for prolonged periods, their presence and distribution in cold environments where they cannot grow serve as a signature of dispersal history in isolation of other factors. Closely related bacteria have been detected in warm anoxic subsurface ecosystems, suggesting that seabed fluid flow from deep biosphere environments is delivering thermophiles as spores to the cold ocean where they might passively disperse great distances through ocean currents. However, even in the globally interconnected ocean, these hardy “thermo-spores” are not necessarily cosmopolitan: in a global survey using incubation experiments, thermo-spores were not detectable in all sediments tested. Quantitatively assessing spatial variation in the distribution and abundance of thermo-spores may enable mapping their source(s) and quantifying their dispersal. Since possible pathways of cell transport are not necessarily restricted to this group, thermophilic endospores likely represent a novel model system in which to address the role of dispersal in marine microbial biogeography more broadly.

91 THURSDAY 12 SEPTEMBER 2013

14:00 MICROBIAL SEED BANKS: ECOLOGICAL AND EVOLUTIONARY IMPLICATIONS OF DORMANCY

Invited Lecture by Jay Lennon Department of Biology - Indiana University (USA)

Dormancy is a bet-hedging strategy used by a wide range of taxa, including microorganisms. It refers to an organism’s ability to enter a reversible state of low metabolic activity when faced with unfavorable environmental conditions, including energy limitation. Dormant microorganisms generate a seed bank, which comprises individuals that are capable of being resuscitated following environmental change. Thus, microbial dormancy may help maintain biodiversity and influence the stability of ecosystem processes. After introducing a theoretical framework for microbial seed banks, I will present results from a meta-analysis on the prevalence of dormancy in a variety of ecosystems, including oceans, lakes, soils, and the human gut. In addition, I will discuss results demonstrating the importance of dormancy for the maintenance of microbial diversity and ecosystem functioning. Finally, I will present ongoing research that focuses on the mechanisms of bacterial resuscitation, and the implications of these processes under global climate change scenarios.

92 THURSDAY 12 SEPTEMBER 2013 OS-9. Microbial metabolic specialization: causes and ecological consequences

14:30 BACTERIAL COMMUNITY STRUCTURE AND DISSOLVED ORGANIC MATTER COMPOSITION IN SUBSURFACE KARST WATER POOLS: INTERPLAY BETWEEN HABITAT FILTERING AND FLOODING EVENTS

Tanja Shabarova, Limnological Station, University of Zurich (Switzerland) Coauthors: Villiger J, Morenkov O, Niggemann J, Dittmar T, Pernthaler J

Bacterial diversity, community assembly, and the composition of the dissolved organic matter (DOM) were studied in three subsurface epiphreatic karst pools with different flooding regimes. We hypothesized that microorganisms collected from various niches would face environmental filtering in the pools towards a “typical” karst water community, and that this selection would be reflected in specific transformations of DOM. Phylogenetic clustering revealed that the bacterial assemblages of the influx water had been already shaped by deterministic processes. While these initial communities harbored lineages with large distances to known diversity, the “core” (present in all samples) were predominantly related to bacteria from subsurface or surface aquatic environments. The stagnation of karst water in the pools reproducibly resulted in a decline of bacterial diversity and a community shift towards a subset of closely related genotypes. A small number of operational taxonomic units (OTUs) related to beta-Proteobacteria were responsible for the clustering of samples according to water residence time, and a strong temporal signal was also found for OTUs from other lineages. By contrast, several OTUs affiliated with Cytophagaceae and Flavobacteriaceae were more tightly related to different floodings. These flood events were also a main determinant of DOM composition. In addition, a distinct transformation of the molecular composition of DOM was observed over time, reflecting the utilization of the available DOM sources by the “core” microbial assemblages in the pools.

93 THURSDAY 12 SEPTEMBER 2013 OS-9. Microbial metabolic specialization: causes and ecological consequences

14:45 DISSIMILATORY METAL-REDUCING MICROBIAL ACTIVITY IN SHALLOW SALINE ENVIRONMENTS

Jacqueline Rochow, Flinders University of South Australia, Adelaide (Australia) Coauthors: Dann L, How D, Shakya S, Newton K, Paterson J, Delpin M, Mitchell JG

Dissimilatory metal-reducing bacteria (DMRB), which use oxidised metals as terminal electron acceptors when no oxygen is available, are ubiquitous in waterways. Most research on these bacteria has focused on their potential for power production in microbial fuel cells (MFCs) and their use in removing heavy metal contamination. While much research has been done on DMRB in deep ocean sediments, very little work examines their activity in shallow estuaries and , with variable oxygen availability. Using a new design of single-celled, liquid-only MFCs that simulate the oxygen availability of shallow saline water environments, the activity of a mixed community from the St Kilda Mangroves was measured for DMRB activity via electron donation to an anode, and community growth and enrichment was measured via flow cytometry. The presence of the anode resulted in the enrichment of bacteria related to metal reduction and an increased power production over time, as is normally found in a standard fuel cell, despite the lack of a truly anaerobic anodic environment. This study indicates that DMRB activity is easily stimulated even in shallow saline waters such as mangroves, which shows promise for bioremediation of waterways and indicates possible significant DMRB activity in the normal metabolism of microbiological communities.

94 THURSDAY 12 SEPTEMBER 2013 OS-9. Microbial metabolic specialization: causes and ecological consequences

15:00 TRENDS OF MICROBIAL TAXA AND FUNCTIONAL ADAPTIVE RESPONSES OF SEDIMENT MICROBIOME REMAIN CONSERVED IN DIFFERENT LAND USE TYPES

Sanjay Swarup, Department of Biological Sciences, National University of Singapore (Singapore) Coauthors: Nesati V, Wei TJ, Yissue W, Williams RBH, Wuertz S, Steinberg P, Kjelleberg S, Rajal V, Law AWK, Saxena G

Urban catchments are characterized by significant perturbations of top-layer sediments and its microbiome, caused by rain due to high water discharge, velocity and turbulence. Stormwater introduces microbial communities and various physicochemical pressures from catchment of different land use types to the neighboring urban stormwater canals. These environmental pressures affect the water quality, appearance and potential health risks. To improve the water quality and appearance, dense network of canals provide high residence time to adopt self- cleaning approaches based on microbial ecology principles. With this motivation, the aim of the present study was to understand the effects of rain perturbation on the structure and function of sediment communities of different land use types immediately after storm events and during successional periods in the canals. To investigate this, a mesocosm experiment was conducted in 2m long flumes with sediment and water seeded from residential and industrial sites after a rain event. A third sediment type was created by mixing the two sediment types and termed as mixed. A linear flow regime was designed based on partial replacement and dilution principle. The experiment was conducted with complete random design of three replicates each of reactors for three sediment types for 30 days period with daily measurement of 12 environmental parameters and 10 time points for analyses of replicated samples for ions, metals, cell counts, T-RFLP, metatranscriptome and metabolome. Non-metric Multidimensional Scaling (NMDS) and Analysis of Similarity (ANOSIM) showed that microbial communities shifted in a clear successional pattern. Shifts in microbial community structures of all land use types were maximal midway (day 8) during the successional period. The changed community tends to return to the original community at later time points (day 30). However, no difference was observed between the microbial communities from different land use types. The relative abundance of core 21 metabolites showed significant differences (ANOSIM: p<0.05) among the land use types at day 8 but there were concordant changes at all other times. Similar successional trend of microbial taxa irrespective of land use types indicates towards an inherent property of microbial communities to return to the original community after the rain events and that the microbial communities may recruit different pathways in coping with this perturbation.

95 THURSDAY 12 SEPTEMBER 2013 OS-9. Microbial metabolic specialization: causes and ecological consequences

15:15 BEING ACTIVE AS A MICROBE IN GLACIER-FED STREAMS

Linda Wilhelm, Department of Limnology, University of Vienna (Austria) Coauthors: Besemer K, Fasching C, Singer G, Battin T

Glaciers are now recognized as a biome harboring highly diverse microbial communities. Upon glacier retreat, microorganisms can be released into glacier-fed streams, where they may ultimately form benthic biofilms or they are transported downstream with the water flow. Although studies increasingly classify and characterize microbial communities in glacial ecosystems, investigations on their apparent activity are lacking. Based on 16S rDNA and rRNA pyrosequencing of rock and sand biofilms in 26 glacier-fed streams, we explored the relationship between the bulk (rDNA) and the active (rRNA) microbial communities. Diversity and community composition of rock and sand biofilms were similar among our study streams. However, we found a significant difference in community composition of the bulk and active communities. While rRNA and rDNA were positively correlated at phyla level, this relationship was weaker at the family level. In both rRNA and rDNA, Comamonadaceae was the most dominant family, which is in line with other studies on glacial ecosystems. However, many families (e.g. Moraxellaceae or Acetobacteriaceae) were disproportionately more abundant in the active community, compared to their relative recovery in rDNA. In both rock and sand biofilms we found a large number of rare taxa, which had higher relative abundances in the rRNA compared to rDNA. These results suggest that biofilms of glacier-fed streams have very dynamic rank abundance curves, which may be attributable to fluctuating environmental conditions. A high turnover of the community, where microorganisms repeatedly enter and exit the “seed bank”, may contribute to the maintenance of microbial biodiversity in these harsh environments.

96 THURSDAY 12 SEPTEMBER 2013 OS-9. Microbial metabolic specialization: causes and ecological consequences

15:30 PHENOTYPIC HETEROGENEITY IN BACTERIAL METABOLIC ACTIVITIES FOR GROWTH DURING FLUCTUATING NUTRIENT SUPPLY

Frank Schreiber, ETH Zurich, Dept. of Environmental System Sciences and Eawag (Switzerland) Coauthors: Lavik G, Littmann S, Kuypers M, Ackermann M

Genetically identical cells that live in a homogeneous environment often show substantial variation in their biological traits; such variation is called phenotypic heterogeneity. The level of phenotypic heterogeneity can evolve, because it has a genetic basis and it provides - as suggested by theoretical studies - a population of genotypes with an efficient way to respond to uncertain environments. However, direct experimental evidence that such metabolic heterogeneity provides individuals with a growth advantage in fluctuating environments is missing on a single-cell level. In addition, it is until now not known if phenotypic heterogeneity is relevant for bacterial metabolic activities that contribute to biogeochemical cycles. We use a combination of single-molecule mRNA FISH and nanometer-scale secondary ion mass spectrometry (nanoSIMS) to experimentally investigate how phenotypic heterogeneity affects bacterial metabolic activity and growth under fluctuating environmental conditions. Specifically, we investigate phenotypic heterogeneity in N2- + fixation in the model organism Klebsiella oxytoca under fluctuating NH4 concentrations. We show that nitrogenase (key enzyme for N2-fixation) expression and N-assimilation from N2 is bistable if + cells are grown under limited NH4 supply. Heterogeneous populations retain a positive growth + + rate when exposed to a sudden switch from limited NH4 supply to NH4 -deplete conditions. We further use a nanoSIMS-based pulse-chase approach to study the benefits for nitrogenase-active + cells under fluctuating NH4 supply. We hypothesize that phenotypic heterogeneity in metabolic activity is a microbial bet-hedging strategy in the light of nutrient fluctuations. Moreover, + phenotypic heterogeneity of N2-fixation in the presence of NH4 provides an explanation for recently measured heterotrophic N2-fixation rates in the presence of fixed N-sources in many marine and freshwater systems

97 THURSDAY 12 SEPTEMBER 2013 OS-8B. Bacterial biogeography and dispersal in a changing world

16:15 ABUNDANCE AND BIOGEOGRAPHICAL PATTERNS OF THE MICROBIAL PLAYERS IN THE THROUGHOUT THE ATLANTIC

Eva Sintes, Dept. of Limnology & Oceanography, University of Vienna (Austria) Coauthors: De Corte D, Steiner P, Ouillon N, Herndl GJ

Ammonia oxidation and nitrate assimilation are two of the main pathways of the nitrogen cycle. These two processes are expected to be relatively more important in deep oceanic waters, where sources of energy are scarce and organic matter is recalcitrant and relatively poor in nitrogen. To evaluate the potential for ammonia oxidation and nitrate assimilation in deep waters, samples were taken from the epipelagic to abyssopelagic waters of the Western Atlantic at 51 stations along a latitudinal transect from 65°N to 55°S. The abundance of two different groups of archaeal ammonia oxidizers (AOA), subsequently termed low ammonia concentration (LAC) and high ammonia concentration (HAC), and of nitrate assimilating Bacteria were determined by q-PCR using the archaeal amoA (encoding ammonia monooxygenase) and nasA gene (encoding nitrate assimilatory reductase), respectively. HAC-AOA dominated in epipelagic (on average HAC/LAC: 391) and high latitude environments (HAC/LAC: 141), while LAC-AOA dominated in bathy- and abyssopelagic waters (HAC:LAC: 0.2) more prominently at low latitudes. A higher fraction of putatively nitrate assimilating bacteria was found in the lower bathypelagic waters of the Subantarctic (51%) and the North Atlantic Drift (20%) province and in lower mesopelagic waters of the South Atlantic province (20%) than in the epipelagic waters and the Arctic region (0-3%). The community composition was assessed throughout the Atlantic by cloning and sequencing, for both the AOA and the nasA containing bacterial community, and by T-RFLP and 454-pyrosequencing for AOA. AOA communities showed a bipolar distribution, while nasA gene containing bacteria seems to display an hemisphere-asymmetrical taxon distribution, pointing to different barriers for dispersal of these two functional groups. Taken together, our results indicate the potential for ammonia oxidation and nitrate assimilation in deep waters throughout the Atlantic, however, exhibiting a pronounced biogeographic distribution of the AOA and nitrate assimilating Bacteria.

98 THURSDAY 12 SEPTEMBER 2013 OS-8B. Bacterial biogeography and dispersal in a changing world

16:30 ABUNDANCE AND DEPOSITION FLUXES OF AIRBORNE MICROORGANISMS OVER THE OCEANS AT TROPICAL AND MID-LATITUDES

Eva Mayol, IMedEA (CSIC-UIB), Esporles (Spain) Coauthors: Arrieta JM, Jimenez MA, Duarte CM

The surface ocean exchanges microbes with the atmosphere by aerosolization of marine organisms and deposition of airborne microbes carried by the wind. There is a paucity of data on the abundance of airborne microorganisms over the ocean with most of the available data corresponding to coastal locations and little information on the open ocean. Data on wind transport and deposition of airborne microbes over the ocean are also scarce. We will present estimates of the abundance of airborne microbes over the oceans at tropical and mid-latitudes in the Atlantic, Indian and Pacific oceans from samples collected during the Malaspina 2010 Circumnavigation Expedition. Transport and deposition fluxes were estimated using environmental parameters and estimates of marine aerosolization. The global character of this sampling allows the discrimination of different areas of the ocean with different contents of airborne microorganisms. Optical aerosol measurements from satellite images were calibrated using the measured abundances of biological particles in order to allow modeling the distribution of bioaerosols at tropical and mid-latitudes.

99 THURSDAY 12 SEPTEMBER 2013 OS-8B. Bacterial biogeography and dispersal in a changing world

16:45 EFFECT OF DRYING-REWETTING CYCLE AND DISPERSAL TIMING ON COMPOSITION AND FUNCTION OF BACTERIAL METACOMMUNITY

Anna J Székely, Limnology Dept. - Evolutionary Biology Centre, Uppsala University (Sweden) Coauthors: Langenheder S

Drought-rewetting cycles are one of the most prevalent natural disturbance episodes of freshwaters that might change in frequency and intensity due to climate change. However, little is known about the ecologically relevance of this process on aquatic bacterial community and metacommunity composition and function. Here we present an experimental study where sets of freshwater communities (metacommunities) were dried and rewetted under controlled conditions. Dispersal treatment was applied at different time points after rewetting to test for the effect of dispersal on stabilizing stressed metacommunities. Function of bacterial communities was assessed by measuring respiration and functional diversity with EcoBiolog plates. Metacommunity composition and diversity were defined by 454-pyrosequencing of 16S rRNA gene. Specific respiration rate, functional beta-diversity increased during drying process. After rewetting specific respiration rate could not reach before drying values, EcoBiolog profile and community composition changed, functional and taxonomical alpha-diversity increased, while beta-diversity decreased. Dispersal usually lowered beta-diversity but the most significant establishment success of dispersed bacteria and function modifying effect was measured, when dispersal happened earlier, during log-phase of bacterial growth. Our results proved that drying- rewetting process significantly effects both function and composition of bacterial metacommunities. The effect of the process differs between the different phases of the process (drying or rewetting), and on the level examined (community or metacommunity). Dispersal can mitigate the stress effect but its effect depends on timing.

100 THURSDAY 12 SEPTEMBER 2013 OS-8B. Bacterial biogeography and dispersal in a changing world

17:00 SPATIOTEMPORAL INVESTIGATIONS OF BENTHIC BACTERIAL COMMUNITIES ALONG A SEDIMENT GRADIENT IN THE GERMAN BIGHT

Rebecca Störmer, Alfred Wegener Institute for Polar and Marine Research, Helgoland (Germany) Coauthors: Wichels A, Gerdts G

Abundance and distribution of species and factors influencing them are crucial to understand ecosystem functioning and to predict environmental changes. To date several studies have been undertaken investigating spatiotemporal variations of pelagic bacterial communities in marine systems. So far, spatial factors, such as salinity, more than temporal factors are believed to shape the pelagic bacterial community assembly. Studies examining the biogeography of their benthic counterparts on spatiotemporal scales in marine habitats are surprisingly rare. To our knowledge the present study describes differences within the benthic bacterial community composition along a sediment gradient in the German Bight for the very first time. A dataset encompassing 52 samples retrieved from six sampling sites over an annual cycle was subjected to 16S amplicon sequencing targeting the highly conserved V1-V5 regions in the bacterial genome. Diversity and structure of the benthic bacterial communities was elucidated using ordination methods and cluster analyses. Relationships between bacterial community structure and spatiotemporal factors were investigated applying distance-based multiple regression models. Our results demonstrate that the bacterial community structure differed significantly in refer to spatial factors (sediment composition) but not when taking temporal factors into account. Interestingly, we observed no significant spatiotemporal differences regarding the overall diversity of bacterial communities. From the phylogenetic perspective all sediment types were dominated by the phyla Proteobacteria and Bacteroidetes. However, their individual phylogenetic classes displayed distinct cluster for either sandy or silty habitats, respectively. Organisms affiliated to Deltaproteobacteria dominated silty sediments while Gammaproteobacteria were found to colonise sandy sediments, predominately. Representatives belonging to the class of Betaproteobacteria were detectable almost exclusively in sandy sediments while Flavobacteria (Bacteroidetes) form apparently different cluster according to the silt content of the sediments. This study highlights that the assembly of benthic bacterial communities, just as for pelagic bacterial communities, is predominately driven by spatial factors. We believe that the outcome of this study represents an important step towards our understanding of the ecological role of benthic bacterial in the German Bight and marine sediments in general.

101 THURSDAY 12 SEPTEMBER 2013 OS-8B. Bacterial biogeography and dispersal in a changing world

17:15 POLE TO POLE BIOGEOGRAPHY OF SURFACE AND DEEP MARINE BACTERIAL COMMUNITIES

Jean-François Ghiglione, Banyuls Oceanological Observatory, CNRS-LOMIC (France) Coauthors: Galand PE, Pommier T, Pedros-Alio C, Mass E, Kirchman DL, Lovejoy C, Yager PL, Murray AE

The Antarctic and Arctic regions offer a unique opportunity to test factors shaping the biogeography of marine microbial communities as they represent extremes in geographic separation yet share similar selection pressures. Here we report the most comprehensive comparison of bacterioplankton diversity between the polar oceans conducted to date, using standardized methods for pyrosequencing the V6 region of 16S rRNA gene. This effort included lower latitude ocean to provide a global perspective for a global comparison of 837 844 sequence tags. Unexpectedly, we found a clear difference between Southern and Arctic Ocean microbiomes: 78.0% of the OTUs were unique to the Southern Ocean and 70.4% were unique to the Arctic Ocean. Even though polar ocean bacteria were more similar to each other than to lower latitude pelagic communities, analyses comparing depths, seasons and coastal versus open ocean demonstrated that Southern and Arctic Ocean bacterioplankton communities always clustered separately. Coastal surface Southern and Arctic Ocean communities were more dissimilar than open ocean communities. In contrast, deep ocean microbiomes were less different between poles and to lower latitude deep ocean waters, and they contained different patterns of diversity accumulation compared to surface, suggesting different mechanisms controlling surface and deep ocean community structures. We propose that surface bacterioplankton are more influenced by contemporary environmental conditions such as light, resource variability and climate, whereas deep communities are structured by a history of longer isolation and connectivity through ocean circulation. This work has identified major players in polar coastal and open ocean surface and deep communities, and provides a framework for understanding bacterioplankton biogeography.

102 FRIDAY 13 SEPTEMBER 2013

9:00 GROWTH OF MULTI-SPECIES COMMUNITIES IN TIME AND SPACE: PREDICTIONS FROM GENOME-SCALE MODELS

Invited Lecture by Christopher Marx Department of Organismic and Evolutionary Biology - Harvard University (USA)

To what extent can principles of optimality be used to predict the behaviour and evolution of metabolic systems? I will discuss the use of a particular framework for modelling metabolism, Flux Balance Analysis (FBA), and first consider the degree to which it predicts how metabolic fluxes will redistribute over the course of 50, 000 generations of adaptation of Escherichia coli to glucose minimal medium. Second, I will describe our work evolving synthetic, multi-species consortia in spatially structured environments. Here we have learned about the genetic basis of the emergence of costly, cross-species cooperation and are beginning to use a new framework that embeds FBA into a spatial environment to make predictions about growth of communities in space and time.

103 FRIDAY 13 SEPTEMBER 2013 OS-10. Microbial autoecology and coevolution

9:30 MIXING OF WATER MASSES AND ITS EFFECTS ON MARINE PROKARYOTIC AND VIRAL COMMUNITIES, FREQUENCY OF INFECTED CELLS, AND VIRAL PRODUCTION

Christian Winter, Dept. of Marine Biology, University of Vienna (Austria) Coauthors: Köstner N, Kruspe CP, Muck S, Herndl GJ

The oceanic water column is vertically structured with overlaying water masses that are distinguished by density differences. In this study, we investigated if mixing of meso- and bathypelagic water masses from the Atlantic Ocean exerts a detectable effect on the level of mortality of prokaryotic cells due to viruses. Also, we asked whether a response to mixing was due to the entire prokaryotic community or mostly due to viruses infecting either Bacteria or Archaea. To address these questions, we conducted experiments with prokaryotic cells from the North Atlantic Deep Water (NADW), the Mediterranean Sea Overflow Water (MSOW), and the Antarctic Intermediate Water (AAIW) during a cruise in the Atlantic Ocean. Tangential-flow filtration was used to obtain prokaryotic concentrates and virus-free water from each water mass to set-up experiments consisting of 7 different treatments (2 controls, 2 transplantation treatments, 3 interaction treatments; duplicates in 20 L carboys). The experiments were incubated at in situ temperature for up to 72 hours. Sub-samples for prokaryotic and viral abundance were taken every 4 hours and for prokaryotic and viral community composition every 24 hours. Prokaryotic and viral abundance was determined flow-cytometrically. Bacterial and archaeal community composition was determined by terminal restriction fragment length polymorphism analysis (T- RFLP). Viral community composition was assessed by randomly-amplified polymorphic DNA-PCR (RAPD-PCR) analysis using primers targeting two distinct sub-populations of the viral community. Incubating prokaryotes from NADW in MSOW or AAIW water consistently resulted in an increase in the frequency of infected cells and viral production. New viral infections in the incubations were prevented due to the dilution of viruses. Thus, these results can only be due to the induction of the lytic cycle of lysogenic viruses. The bacterial community as well as one of the viral sub- populations was only weakly affected by the experimental treatments. However, Archaea and the second viral sub-population targeted by RAPD-PCR showed strong treatments effects. In summary, the data indicate that the stimulation of the frequency of infected cells and viral production was due to the induction of lysogenic viruses of Archaea.

104 FRIDAY 13 SEPTEMBER 2013 OS-10. Microbial autoecology and coevolution

9:45 SINGLE CELL GENOMICS PROVIDES A CULTIVATION-UNBIASED VIEW OF BACTERIA-PHAGE INTERACTIONS IN THE OCEAN

Jessica Labonté, Bigelow Laboratory for Ocean Sciences, East Boothbay (USA) Coauthors: Swan BR, Stepanauskas R

Viral infections of marine bacterioplankton affect global biogeochemical cycles, microbial community composition and evolution. However, our knowledge about virus-host relationships in the ocean has been limited so far to a small number of cultured representatives. Here we employed single cell genomics to analyze phage-host interactions in situ, without the need for cultivation. We searched for viral DNA in 50 single amplified genomes (SAGs) representing diverse taxonomic groups of marine planktonic Bacteria and Archaea. A total of twelve nearly complete, novel viral genomes, representing all three major phage families (i.e. Myoviridae, Podoviridae, and Siphoviridae) were recovered from a wide range of hosts. For the first time, viruses were associated with hosts from several taxonomic groups that contain no cultured relatives, such as Verrucomicrobia, the Marine Group A (SAR406) and Thaumarchaea. Our results suggest that persistent and chronic infections may be common for narrow host-range phages, such as Podoviridae. High genomic diversity and involvement in horizontal gene transfer characterize the discovered temperate and lytic Siphoviridae phages. Our results suggest a broader host range for some Myoviridae phages, as compared to cultivation-based data. The employed research approach offers new opportunities for more representative studies of viral ecology and roles in the ocean.

105 FRIDAY 13 SEPTEMBER 2013 OS-10. Microbial autoecology and coevolution

10:00 THE RESPONSE OF POLYNUCLEOBACTER NECESSARIUS TO LIGHT IN A HUMIC LAKE

Jens Glaeser, Institute of Microbiology and Molecular Biology, Giessen (Germany) Coauthors: Glaeser SP, Leunert F, Förstner KU, Allgaier M, Grossart HP

Epilimnic bacterioplankton of humic Lake Grosse Fuchskuhle is often dominated by Polynucleobacter necessarius, a ubiquitous ultramicrobacterium of the Burkholderiales (Betaproteobacteria). Hence cultured representatives of this species provide useful microbial model systems for investigating the cellular response to diurnal changes in environmental factors, e.g. light, nutrients and oxidative stress. In the SW basin of the artificially divided Lake Grosse Fuchskuhle, epilimnic bacteria were strongly inhibited by sunlight exposure. Either light or light mediated photochemical reactions may cause this effect leading to a decreased uptake of radiolabelled substrates, a decreased bacterial DNA synthesis and an increased fraction of membrane damaged cells. Bacteria were able to recover from the sunlight mediated inhibition. Subsequently, we assessed the underlying molecular responses in a cultured representative of P. necessarius. Dialysis bag cultures of this strain were grown in the surface water layer of the SW basin. Cultures exposed to sunlight and cultures covered with black plastic foil were sampled at 2 pm on a day with high solar radiation. Additional cultures were harvested before sunrise at 4 am after a period of ca. 6 hours without sunlight. In sunlight exposed cultures Illumina sequencing of total RNA extracts revealed a strong decrease in mRNA levels of genes encoding for central cellular functions such as energy metabolism (e.g. citric acid cycle genes), anabolic processes (e.g. synthesis of amino acids) and genes involved in cell division. In contrast, genes encoding oxidative stress response mechanisms (e.g. peroxiredoxin) were increased. Two dimensional gel electrophoresis of proteins from laboratory P. necessarius culture experiments revealed that light and oxidative stress caused a global proteome changes. In summary, our data show that P. necessarius strongly respond to sunlight exposure. Molecular mechanisms were triggered to overcome the effects of sunlight exposure or light mediated photochemical reactions, which are in turn prerequisite for Polynucleobacter to survive in the upper, sunlit water layer of freshwater ecosystems.

106 FRIDAY 13 SEPTEMBER 2013 OS-10. Microbial autoecology and coevolution

10:15 GREATER THAN 99% 16S rRNA GENE SIMILARITY: BROAD ECOLOGICAL AND GENOMIC DIVERSITY WITHIN A PLANKTONIC POLYNUCLEOBACTER TAXON

Martin Hahn, University of Innsbruck (Austria) Coauthors: Jezbera J, Jezberova J, Simek K, Camacho A, Koll U

Polynucleobacter bacteria evolved two distinct lifestyles, they either dwell as obligate endosymbionts of ciliates or they live as planktonic bacteria in freshwater systems. One subgroup currently known as subspecies P. necessarius ssp. asymbioticus contains exclusively free-living members sharing 16S rRNA genes with greater than 99.2% sequence similarity. This taxon is characterized by a cosmopolitan distribution and apparently ubiquitous occurrence in standing freshwater habitats. This group represents an important part of freshwater bacterioplankton comprising up to 60% of total cell numbers. We further divided this seemingly homogenous taxon in subgroups and searched for differences in ecological distribution along gradients of environmental parameters like pH or climate conditions by using cultivation-independent methods. This revealed subgroup-specific differences in distribution, for instance, some subgroups were exclusively found in acidic and others exclusively in alkaline waters. One subgroup was found to be restricted to the tropical climate zone but is at least present on four continents. Another subgroup could only be detected in Antarctic freshwater systems so far. Differences in ecophysiological adaptations suggested by the distribution studies could be confirmed by lab experiments (e.g. thermal adaptation) and by transplantation experiments between contrasting environments. Genome comparisons revealed only very minor differences in general genome features like genome size and GC value. On the other hand, pronounced difference in gene content were detected, which clearly suggest large subgroup-specific differences in ecological adaptation. In conclusion, the wide range of ecological conditions covered by this phylogenetically shallow taxon (>99% 16S rRNA similarity) can be explained by adaptive radiation: ubiquity by diversification.

107 FRIDAY 13 SEPTEMBER 2013 OS-10. Microbial autoecology and coevolution

10:30 ECOLOGICAL SIGNIFICANCE AND ECOPHYSIOLOGICAL FEATURES OF AMMONIA OXIDIZING THAUMARCHAEOTA FROM HYPOXIC WATERS OF THE BALTIC SEA

Carlo Berg, IOW - Leibniz Institute for Baltic Sea Research, Rostock (Germany) Coauthors: Vandieken V, Listmann L, Thamdrup B, Jürgens K

Marine oxygen deficient areas are hotspots for the biogeochemical cycling of nitrogen and carbon. New processes and key organisms have been discovered in the last years. For example, members of the Archaea, and not Bacteria are often responsible for ammonia oxidation. This also applies for the Baltic Sea, where ammonia-oxidizing Archaea (AOA), represented by the thaumarchaeotal subcluster GD2, dominate in hypoxic waters. Aiming to elucidate the significance of Thaumarchaeota for nitrification and their adaptations, and ecological role, we performed both field studies in the central Baltic Sea and ecophysiological experiments with enrichments of 15 Thaumarchaeota. Throughout the nitrification zone, NH4 rate measurements and catalyzed reporter deposition fluorescence in situ hybridization (CARD-FISH) revealed that the pattern of nitrification activity followed closely the distribution of the thaumarchaeotal subcluster GD2 in the water column. Remarkably, nitrification was still detectable after spiking with lower in situ-like concentrations of sulfide, which points to special adaptations of this thaumarchaeotal cluster to periodically occurring sulfide pulses. Supporting, we detected an elevated nitrification potential in water taken from a sulfidic depth. Application of the Archaea-specific hypusination inhibitor GC7 resulted in significantly reduced nitrification activity, confirming the major role of Archaea for this process. Enrichments (>90% purity) of AOA from the central Baltic Sea that were maintained for more than 2 years in the laboratory were studied with respect to chemoautotrophy and ammonia oxidation. Stoichiometric analysis revealed that the cells grew fully autotrophically while oxidizing 10 N for 1 C incorporated into biomass. Our study provides compelling evidence that ammonia oxidation in hypoxic waters of the Baltic Sea is mainly driven by Thaumarchaeota and not by Bacteria, and that they are key prokaryotes for N and C cycles. Their occurrence and maintained nitrification potential also in anoxic, sulfidic waters point to special adaptations of this thaumarchaeotal cluster to this habitat with a reduced sensitivity against hydrogen sulfide.

108 FRIDAY 13 SEPTEMBER 2013 OS-S2. Protists: the ecological meaning of species specific morphologies

11:15 DIATOM NANOSTRUCTURES IMPROVE NUTRIENT UPTAKE

Jim Mitchell, Flinders University, Adelaide (Australia) Coauthors: Seuront L, Doubell MJ, Losic D, Voelcker NH, Seymour J, Lal R

Diatoms are important autotrophs distinguished by surficial frustules with intricate designs of unknown function. We show some designs constrain diffusion to positively alter nutrient uptake. In nutrient gradients of 4 to 160 times over <5 cm, the screened-chambered morphology of Coscincodiscus sp. biases the nutrient flux towards the cell by at least 3.8 times the flux to the seawater. In contrast, the open-chambers of Thalassiosira eccentrica produce at least a 1.3 times flux advantage to the membrane over Coscincodiscus sp. when nutrients are homogeneous. Diffusion constraint explains the success of particular diatom species at given times and the overall success of diatoms. The results help answer the unresolved question of how adjacent microbes compete against each other. Furthermore, diffusion constraint by supramembrane nanostructures to alter molecular flux suggests that microbes take up nutrients in a way not considered by the standard smooth-surface equations used for nutrient uptake.

109 FRIDAY 13 SEPTEMBER 2013 OS-S2. Protists: the ecological meaning of species specific morphologies

11:30 INTERACTIONS BETWEEN MARINE BACTERIA AND UNICELLULAR EUKARYOTES

Stina Israelsson, Linnaeus University, EEMiS, Kalmar (Sweden) Coauthors: Axelsson-Olsson D, Pinhassi J

Bacteria in aquatic environments are the principal food source for several unicellular eukaryotes (protists), and as such constitute the basis for the microbial food web. There are also indications that bacteria can have negative effects on eukaryotic taxa, including algae. However, few attempts have been made to thoroughly characterize interactions between aquatic bacteria and protists. Here we investigated interactions between 18 genome sequenced marine bacterial species and three phagotrophic protists that are established model species for investigating microbial interactions. All bacteria were screened against all protists for interaction effects on both bacteria and protists over two weeks. As expected, protists efficiently grazed on most bacteria. Strikingly however, 10, 5 and 3 bacterial isolates were capable of lysing Acanthamoeba polyphaga, Tetrahymena pyriformis and Euglena gracilis, respectively. In addition to lysis, morphological changes of protists were also frequently observed. Experiments with A. polyphaga (protozoa) showed that some bacteria, e.g. BAL38 (Bacteroidetes), grew efficiently in presence of continuously viable protozoa. Also, growth curves in low-nutrient media showed that nutritional stress could favour bacterial growth in co-culture, as observed with SKA58 (Alphaproteobacteria). Interestingly, some bacteria, e.g. SKA34 (Gammaproteobacteria), showed improved survival in presence of living protozoa, and were observed in protozoa vacuoles. These findings have interesting similarities to those obtained with several human pathogens, including Legionella, where the protozoa interaction decisively determines the virulence and epidemiology of the pathogen. Our results show that many bacteria were remarkably capable of surviving and even actively killing bacterivorous protists, although grazing occurred as expected. Lysis of grazers may primarily be a bacterial defence mechanism, but could also be a way of accessing nutrients. In fact, it has been shown that several of our studied isolates have known virulence genes. Together, our results imply that interactions between marine bacteria and protists are more diverse than generally recognized and that environmental factors such as nutrient accessibility could be decisive for defining the interaction effect. This has important implications for understanding ecological and evolutionary consequences of population dynamics in bacteria and protists, and pathogenic potential of marine bacteria.

110 FRIDAY 13 SEPTEMBER 2013 OS-S2. Protists: the ecological meaning of species specific morphologies

11:45 ACHIEVEMENTS AND LIMITATIONS OF HIGH-THROUGHPUT SEQUENCING FOR DIVERSITY ASSESSMENT OF MARINE PLANKTONIC CILIATES

Luciana Santoferrara, University of Connecticut (USA) Coauthors: Grattepanche JD, Grant J, Katz LA, McManus GB

The use of high-throughput sequencing has changed the way we study and understand microbial ecology, and has become a widespread method to analyze prokaryote and protist diversity and distribution. For aquatic microbial eukaryotes, most previous works have been based on hypervariable regions of the SSU rDNA gene amplified by universal primers. However, the tremendous richness and complexity of protists at a global scale can mask major patterns at lower taxonomic levels. In addition, the available computational tools and sequence databases have been based mostly on prokaryotes as models, and thus are not always optimal for work on eukaryote microbes. We used taxa-specific libraries of partial SSU rDNA pyrosequences (454 Roche) and customized bioinformatic pipelines to study the marine planktonic ciliates in Long Island Sound (USA) during spring and summer. Also, we obtained data by microscopy, thus exploiting the advantage offered by ciliate morphology for taxa classification, and by Sanger- sequenced clone libraries. Using a similarity level of 99% for pyrosequence clustering, the richness of Operational Taxonomic Units (OTUs) varied markedly with pipelines: the original data provided estimations up to one order of magnitude higher than data subjected to either filtering of rare OTUs (≤5 reads; <4% of total sequences) or denoising procedures. However, most of the extra OTUs in the original dataset were impossible to classify reliably, while some meaningful OTUs were eliminated by denoising. In the dataset filtered for rare sequences, about 40% of OTUs (90% of total sequences) were identical or clearly linked to previously sequenced phylotypes. The remaining OTUs may correspond to 1- variants of other OTUs caused by either PCR/ sequencing errors or the presence of multiple copies of the SSU rDNA gene in some taxa, 2- actual variants of other OTUs (closely related phylotypes), 3- known taxa that were not sequenced before, or 4- novel lineages. The level of agreement between data from pyrosequencing and microscopy was similar for taxa with clear morphology and taxa revealed as cryptic in our previous species-specific analyses. Finally, the comparison between the two analyzed periods showed similarities in the diversity levels and differences in the assemblage structure, both for dominant and rare taxa. Thus, despite the fraction of diversity that cannot be resolved yet, we developed a promising tool to study the dynamics and biogeography of planktonic ciliates.

111 FRIDAY 13 SEPTEMBER 2013 OS-S2. Protists: the ecological meaning of species specific morphologies

12:00 ALL YOU CAN EAT: PROTISTS (CILIATES AND AMOEBAE) FEEDING ON TOXIC CYANOBACTERIA

Thomas Posch, Limnological Station, Institute of Plant Biology - University of Zurich (Switzerland) Coauthors: Eugster B, Salcher MM, Dirren S

Mass occurrences of harmful filamentous cyanobacteria are of increasing importance in lakes due to ongoing global warming and changing nutrient stoichiometry. Cyanobacteria may produce secondary metabolites being toxic for eukaryotes. Best known are the microcystins (MCs), cyclic heptapeptides, which are efficient inhibitors of eukaryotic protein phosphatases 1 and 2A. Potential consumers get in direct contact with endotoxins when filaments are digested. Thus, cyanobacteria are often regarded as toxic for all consumers; however various protists can be efficient predators of filaments. Up to now, most work focused on the ciliate Pseudomicrothorax dubius feeding on filamentous Oscillatoria spp. (Cyanophyceae). Here, we report on ciliate species from various taxonomic groups (Obertrumia aurea, Trithigmostoma cucullulus, Paraurostyla weissei, Holosticha pullaster) and some amoeboid genera feeding on the harmful cyanobacterium Planktothrix rubescens. Besides the documentation of their curious feeding behaviour we analyse (i) how these protistan species are able to survive their toxic diet, and (ii) how protists react when confronted with non-toxic mutants of cyanobacteria. For the amoeboid genera we have good indications that detoxifying mechanisms happen in symbiosis with bacteria. In the case of ciliates, it is still unknown if the mentioned species have other protein phosphatases which are not affected by microcystins or if ciliates metabolize toxins to less potent compounds via linkage to antioxidants.

112 FRIDAY 13 SEPTEMBER 2013

12:15 KEEP LOOKING: THE POWER OF DIRECT OBSERVATION IN MICROBIAL ECOLOGY

Invited closing Lecture by Roman Stocker (sponsored by QIAGEN) Department of Civil and Environmental Engineering, Massachusetts Institute of Technology (USA)

At a time when microbial ecology is largely traveling along genomic roads, we cannot forget that the functions and services of microbes depend greatly on their behaviors, encounters, and interactions with their environment. New technologies, including microfluidics, high-speed video- microscopy and image analysis, provide a powerful opportunity to spy on the lives of microbes, directly observing their behaviors at the spatiotemporal resolution most relevant to their ecology. I will illustrate this 'natural history approach to microbial ecology' by focusing on marine bacteria, unveiling striking adaptations in their motility and chemotaxis and describing how these are connected to their incredibly dynamic, gradient-rich microenvironments. Specifically, I will present (i) nanometer-resolution imaging at thousand frames per second to demonstrate that marine bacteria can exploit a buckling instability in their flagellum to actively steer, and (ii) microfluidic techniques and experiments to capture the dramatic chemotactic abilities of bacterial pathogens towards the roiling surface of coral hosts. Through these examples, I aim to convince you that direct visualization can foster a new layer of understanding in microbial ecology.

113 POSTER SESSIONS

MONDAY 9 SEPTEMBER 2013, 17:30 PS-1. Ecological consequences of global change in aquatic ecosystems

PS-1.01. EFFECTS OF HUMIC-RICH FRESHWATER DISCHARGE ON COASTAL PELAGIC FOOD WEBS

Agneta Andersson, Dept. of Ecology and Environmental Science - Umeå University (Sweden) Coauthors: Degerman R, Rowe O, Figueroa D, Paczkowska J

A common and established view is that increased inputs of nutrients to the sea, for example via river flooding, will cause eutrophication and phytoplankton blooms in coastal areas. Our studies show that this concept may be questioned in certain scenarios. Climate change has been predicted to cause increased inflow of freshwater to coastal areas in northern Europe. River waters in these areas are often brown from the presence of high concentrations of colored allochthonous dissolved organic carbon (humic carbon), in addition to nitrogen and phosphorus. We studied the effect of riverine loads of C, N and P on marine food webs by using a combination of field, experimental and modeling studies. The northern Baltic Sea was used as model system, a semi- enclosed sea which is highly exposed to colored carbon-rich freshwater discharge. Our field studies showed that river inflow to the coastal system in general had negative effect on phytoplankton primary production, while bacterial production was promoted. Mesocosm experiments where terrestrial dissolved organic carbon was added to the seawater supported this conclusion; however, a negative effect on primary production did not always cause a negative effect on higher trophic, e.g. fish. A minus at lower trophic levels could actually be a plus at higher trophic levels. Finally, a modeling study, using a dynamic ecosystem model based on C, N and P, showed that colored dissolved organic carbon can cause a marked decrease in primary production, mainly because of competition for nutrients from heterotrophic bacteria. Taken together, our results show that the CNP stoichiometry of the inflowing riverine water is a strong governing factor for coastal food webs, affecting the microbial community composition, the size structure and efficiency of the food web and the net ecosystem production. Climate change may lead to a change from net ecosystem autotrophy to increased heterotrophy in coastal systems in northern Europe

114 MONDAY 9 SEPTEMBER 2013, 17:30 PS-1. Ecological consequences of global change in aquatic ecosystems

PS-1.02. EFFECT OF TEMPERATURE IN OUTER MEMBRANE PROTEINS OF STARVED VIBRIO HARVEYI IN SEAWATER

Ines Arana, University of the Basque Country (UPV/EHU), Leioa (Spain) Coauthors: Orruno M, Parada C, Garaizabal I, Vladimir K, Barcina I

A large body of literature has evolved documenting the ability of bacteria to respond to harsh environmental conditions, mainly starvation and temperature changes. So, the acquisition of the viable but nonculturable (VBNC) phenotype in response to adverse conditions has been described for an increasing list of bacteria (1, 3). This response has been studied in detail in Vibrio spp., which has been reported to enter in the VBNC state at temperatures around 5°C (2, 4), and higher temperatures has not or little effect upon Vibrio spp. We have compared the physiological and phenotypical changes occurring in V. harveyi during the exposure in seawater to low (4°C) and high (20°C) temperature. The results obtained by enumeration of total, active and culturable bacteria during the exposure enabled to establish that V. harveyi apparently developed a similar response at 4 and 20°C, entering into the VBNC state in both cases. However, there were differences in the time necessary to display this phenotype. Independently of the time necessary to develop the VBNC state we discern three phases: 1) Phase I or inocula, the initial exposure to seawater. 2) Phase II characterized by the initial decrease in the ability to form colonies on culture media (3 d at 4°C and 6 d at 20°C). 3) Phase III or the VBNC state; most cells do not form colonies but retain the physiological activity (21 d at 4°C and 250 d at 20°C). A proteomic characterization of each phase was carried out by shot-gun methodology. The analysis of the outer membrane subproteome revealed a set of proteins that were detected in all situations. These proteins included OmpW, LapE, OmpA-OmpF porin family, EF-Tu and lipoproteins. However, some proteins were detected exclusively in Phase I (AsmA, HemY, etc) and others varied along the starvation. Finally, the incubation temperature promoted variations in some of the proteins detected, especially in Phase III, i.e. maltoporin or iron transport protein. Therefore, the apparently common VBNC response to temperature of V. harveyi could not be accompanied by a common pattern of change in outer membrane subproteome. 1. Barcina I, Arana I. 2009. Rev Environ Sci Biotechnol 8: 245-255 2. Böer SI, Heinemeyer EA, Luden K, Erler R, Gerdts G, Janssen F, Brennholt N. 2013. Microb Ecol 65(4): 1052-1067 3. Oliver JD. 2010. FEMS Microbiol Rev. 34(4): 415-425 4. Oliver JD, Nilsson L, Kjelleberg S. 1991 Appl Environ Microbiol. 57(9): 2640-2644

115 MONDAY 9 SEPTEMBER 2013, 17:30 PS-1. Ecological consequences of global change in aquatic ecosystems

PS-1.03. TEMPERATURE EFFECTS ON THE GROWTH OF DOMINANT BACTERIAL PHYLOGENETIC GROUPS IN A WARMER COASTAL OCEAN SCENARIO

Nestor Arandia-Gorostidi, Instituto Español de Oceanografía, Gijón (Spain) Coauthors: Huete-Stauffer TM, Alonso-Sáez L, Morán XAG

Increasing temperatures of the ocean surface moves us to study how pelagic communities will be affected by this environmental forcing, since metabolic variables such as growth and respiration rates could be importantly disturbed. Due to its high abundance and key role in different biogeochemical processes, the study of the dynamics of bacterioplankton in warmer conditions acquires special interest. In order to understand the response of specific groups of bacterial communities to temperature, we performed 12 monthly incubation experiments in 2012 under 3 different temperature regimens (in situ, -3°C and +3°C), where in situ temperature varied between 13°C and 21°C. For each temperature, two filtering treatments were performed: C, filtered by 200- µm to remove mesozooplankton and F, additionally filtered by 0.8-µm to remove phytoplankton and bacterial grazers. The single-cell method Catalyzed Reporter Deposition Fluorescent In Situ Hybridization (CARD-FISH) was used to determine changes in the abundance and cell-size of broad phylogenetic bacterial groups (Gammaproteobacteria, Bacteroidetes and Alphaproteobacteria) and two more specific members of Alphaproteobacteria (Roseobacter and SAR11). Under in situ conditions, we found marked differences in the year-round growth rates of the different taxa, with Roseobacter showing the highest rates (above 1 d-1), followed by Bacteroidetes, Gammaproteobacteria and SAR11, which had the lowest rates (usually below 0.5 d-1). In order to study their dependence with temperature, activation energies were calculated for every phylogenetic group. Our results suggest that ongoing ocean surface warming will affect differently some of the major groups of coastal bacteria. Within the whole microbial community, Roseobacter had an average activation energy close to the theoretical value (0.65 eV), higher than any other group (ca. 0.50 eV). Additionally, in F filtering treatment, most groups had lower apparent activation energies, probably caused by substrate limitation, with Bacteroidetes and Gammaproteobacteria showing similar seasonal trends. While temperature may increase the growth rate of most groups, trophic interactions will modulate specific responses. The results suggest that Roseobacter would be more affected by warming than the widespread marine cluster SAR11, indicating that our findings may have important implications for the dynamical and structural response of bacterioplankton communities in a warmer ocean

116 MONDAY 9 SEPTEMBER 2013, 17:30 PS-1. Ecological consequences of global change in aquatic ecosystems

PS-1.04. EMERGENT MACROPHYTES SELECT FOR RELEVANT N-CYCLING BACTERIA IN CONSTRUCTED WETLANDS

Lluis Baneras, Universitat de Girona (Spain) Coauthors: Ramió-Pujol S, Trias R, Vilar-Sanz A, Garcia-Lledó A

Macrophytes have a central role in constructed wetlands, and the coverage and location of vegetation is a significant aspect to be considered in design to ensure an efficient removal of nutrients. Nutrients, especially nitrogen, are preferentially removed from wetlands, not via plant assimilation but via microbial activity. Nitrifying and denitrifying bacteria have complementary ecological niches, due to different electron donor and acceptor requirements, but may coexist in the sediment, in particular in close contact with the root surface. Plants may supply oxygen at the close proximity of the root surface that may favor ammonia oxidizers. At the same time, exudation of simple organics may contribute to speed-up denitrification in the anoxic environment. In this work, we aimed at deciphering plant-microbe interactions of relevant microorganisms in the nitrogen cycle at the root level in free surface constructed wetland. Plant species were chosen among those usually used in constructed wetlands in the Mediterranean area. Composition of both nitrifying Bacteria and Archaea was investigated by qPCR and pyrosequencing of the amoA and 16S rRNA genes. Plant roots, especially those of Typha latifolia and Typha angustifolia, largely impacted the archaeal community whereas the bacterial counterpart remained almost invariable. Changes in the denitrifying bacteria were analyzed according to relevant denitrification genes, the nitrite reductases nirS and nirK, and the nitrous oxide reductase nosZ. Changes in the nir/nos ratio correlated well with potential N2O production rates in the rhizosphere of the different plant species but could not be explained by changes in the presence of volatile fatty acids in the root-exudate composition, except for the alkali bulrush (Bolboschoenus maritimus). Dissimilatory nitrate reduction to ammonia was also affected by plant composition. Our results indicate that plant rhizosphere have implications in multiple steps of the nitrogen cycle and can significantly alter nitrogen removal in wetlands.

117 MONDAY 9 SEPTEMBER 2013, 17:30 PS-1. Ecological consequences of global change in aquatic ecosystems

PS-1.05. BENTHIC BACTERIAL COMMUNITIES IN A CHANGING ARCTIC OCEAN? A CASE STUDY ON THE LAPTEV SEA CONTINENTAL MARGIN

Christina Bienhold, AWI, Bremerhaven (Germany) Coauthors: Wenzhöfer F, Boetius A

The Arctic Ocean is rapidly changing due to increasing temperatures and the loss of sea ice. One of the central questions about the consequences of the shrinking sea ice cover is to what extent primary production and subsequent export of matter to the seafloor will be affected, and how this will influence the structure and functioning of benthic communities in the Arctic. In previous studies, the availability of organic matter at the seafloor has been identified as a main driver of the structure and functioning of benthic bacterial communities, as indicated by strong relationships between biomass, community structure and activity with gradients in organic matter availability (Boetius & Damm 1998, Deep-Sea Res. I 45:239; Bienhold et al. 2012, ISME J 6:724). Here, we contrast surface sediment samples of the Laptev Sea continental slope from two different years, about two decades apart. Samples from the 1990s, when the Laptev Sea was still largely ice- covered throughout the year, provide an ecological baseline against which ecosystem shifts can be assessed. In the past decade, a rapid decline in sea ice cover has occurred, leaving most of the investigated area ice-free during Arctic summer. The Polarstern expedition IceArc (ARK-XXVII/3) returned to the study area in September 2012 to resample the same sites between 60 and 3400 m water depth. Our results suggest that environmental changes in the past two decades may have led to a substantial increase in phytodetritus availability at the seafloor. We compare bacterial biomass, community structure, extracellular enzymatic activities and microbial oxygen uptake between the years 1993 and 2012, and evaluate them in conjunction with environmental parameters. While bacterial biomass (cell counts) and community structure (ARISA fingerprinting) show no systematic changes between the two years, extracellular enzymatic activities seem to have increased as a result of higher food availability. Upcoming analyses of bacterial communities with next generation sequencing will help to link specific taxa to changes in enzymatic activity, as well as to changes in environmental parameters. This comparative study carried out in the framework of the ERC project ABYSS provides insights into bacterial community dynamics in a region dramatically influenced by global change over a time frame of two decades and will help to assess the fate of Arctic benthic ecosystems under future climate scenarios.

118 MONDAY 9 SEPTEMBER 2013, 17:30 PS-1. Ecological consequences of global change in aquatic ecosystems

PS-1.06. COMPOSITIONAL AND FUNCTIONAL CHANGES OF STREAMBED MICROBIAL COMMUNITIES DURING DESICCATION IN AN INTERMITTENT STREAM

Carles Borrego, Catalan Institute for Water Research (ICRA), Girona (Spain) Coauthors: Timoner X, Acuna V, Sabater S

Mediterranean streams are subjected to long summer droughts that may cause the interruption of water flow. During these drought periods, the complete streambed desiccation is an extreme situation that drastically affects both the composition and functioning of microbial communities thriving in different streambed compartments (epilithic, epipsammic and hyporheic). We have studied the microbial community composition of these compartments in a Mediterranean stream before, during and after the non-flow period in order to investigate their differential response to desiccation and recovery. Samples from the three stream compartments were periodically collected along the studied cycle (May-December) and analyzed by massive sequencing to reveal changes in the composition of bacterial communities. Enzymatic activities (leucine aminopeptidase, alkaline phosphatase and β-glucosidase) in the three compartments were also measured to elucidate the potential effect of desiccation on the transformation capacity of organic matter by streambed communities. Major changes during desiccation occurred in the epilithic compartment, which experienced a drastic decrease in the relative abundance of Cyanobacteria and Alpha- and Betaproteobacteria and an increase in members of the Firmicutes. Shannon-Wiener and PD indices calculated for the different compartments along time evidenced the effects of desiccation on the bacterial diversity of epilithic communities. In turn, bacterial communities in the epipsammic and hyporheic compartments, mainly composed of members of the Actinobacteria and the Alphaproteobacteria, remained fairly steady through the whole period. The analysis of beta diversity using UniFrac distances revealed striking differences between habitats (epilithic vs. sandy compartments) and hydrological conditions (flow vs. non-flow). The observed variations may be related to the specific abilities of the different compartments to retain humidity, which greatly influence the response of their indigenous microbial communities to desiccation. The expected increase of drought episodes derived from climate change would probably aggravate these effects, greatly affecting the structure and activity of streambed microbial communities and finally impairing ecosystem functioning.

119 MONDAY 9 SEPTEMBER 2013, 17:30 PS-1. Ecological consequences of global change in aquatic ecosystems

PS-1.07. A RECIPROCAL TRANSPLANT EXPERIMENT STUDYING THE RESPONSE OF LOTIC MICROBIAL COMMUNITIES TO ALTERED WATER SOURCE AND NUTRITIONAL STATE IN A GLACIATED ALPINE FLOODPLAIN

Helmut Buergmann H, Eawag: Swiss Federal Institute of Aquatic Science and Technology, Kastanienbaum (Switzerland) Coauthors: Freimann R, Findlay S, Robinson CT

Climate warming is expected to cause a shift from glacial- to groundwater-dominated water sources in alpine catchments due to receding glaciers In this context, we performed a reciprocal transplant experiment of hyporheic sediments within a Swiss alpine floodplain. Using in-situ flow- through mesocosms, we assessed the influence of water source (groundwater = krenal, glacial water = kryal) and nutritional state (C, N, and P) on the development of the bacterial community composition (BCC) and ecosystem function (EF) in transplanted and native microbial communities. The experimented was replicated over three seasons to account for temporal changes. BCC was characterized using automated ribosomal intergenic spacer analysis and EF by measuring potential activities of eight different enzymes. BCC from both kryal and krenal systems was highly resistant to exposure to a different water source, yet exhibited pronounced EF flexibility. Major factors determining BCC and EF response were sediment origin followed by seasonal variation in BCC. The gradient in seasonal change in BCC showed different strengths in the two water systems. Krenal BCC was more seasonally stable compared with kryal BCC, although functional plasticity was similar in both. This difference in connectivity between BCC and EF suggests that krenal BCC was dominated by generalists, whereas kryal BCC was dominated by specialists. The observed weak effect of altered nutritional state on BCC and EF indicates a complex but hierarchically structured relationship among these factors. We conclude that microbial communities in alpine catchments are able to rapidly buffer the effect of shifts in water source on ecosystem functioning.

120 MONDAY 9 SEPTEMBER 2013, 17:30 PS-1. Ecological consequences of global change in aquatic ecosystems

PS-1.08. HOW SEASONAL TEMPERATURE AND LIMITING FACTORS AFFECT ACTIVITIES OF MARINE HETEROTROPHIC PROKARYOTES: A SEASONAL STUDY IN THE BAY OF MARSEILLE

Benjamin Céa , MIO - Mediterranean Institute of Oceanography, Marseille (France) Coauthors: Van Wambeke F, Lefèvre D, Charriere B, Chirurgien L, Garcia N, Ghiglione JF, Gregori G, Raimbault P

Nutrient availability and temperature are recognized as major regulators of organic carbon processing by aquatic heterotrophic bacteria, however, to date, we have limited information on the interactions between both processes. In addition, temperature effects have been mostly investigated on bacterial production, or respiration, but the temperature effect on the first step of OM utilization as macromolecular hydrolysis has not received much attention. Are temperature effects different according the heterotrophic activity studied? Is there a consequence on OM degradation or bacterial growth efficiency at increased temperatures? To answer these questions, the seasonal variations of temperature effects and of limiting factors on different activities tracking OM degradation have been investigated in the Bay of Marseille, France. Samples have been collected monthly during one year (from 01/02/12 to 28/02/13) in the framework of the SOMLIT network. Temperature versus activity experiments were performed for total community respiration (CR), heterotrophic prokaryotic production (BP), phosphatase activity (phos) and leucine aminopeptidase activity. In addition, nitrate and ammonium (N) vs phosphate (P) vs glucose (G) enrichment experiments were performed, both at in situ temperature and with an increase of 3°C above the in situ temperature. Metabolic activities tested increased with temperature. Some of the kinetics were reaching a plateau or a decrease for temperature above 26°C, such as BP. Within the Arrhenius law domain, Q10 values showed marked seasonal variations (up to 4 fold). The Q10 values of respiration and production varied on a larger extent than those of aminopeptidase or phosphatase. Q10-BP was positively correlated to in situ temperature whereas Q10-phos and Q10-CR were decreasing with increasing in situ temperatures. Q10-CR was higher than Q10- BP on 5 cases over the 9 tested, and thus bacterial growth efficiency was not systematically decreasing after an experimental temperature increase. The first single factor limiting BP was P between May and November (in situ temperatures above 15°C). At the other periods G limitation or co-limitation prevailed (PG, NP or NG). Synergetic/antagonistic effects of temperature and nutrient limitation are examined in relation with the biogeochemical environment, as well as consequences of varying Q10 on the successive steps of degradation of organic matter: hydrolysis of polymers, assimilation and respiration.

121 MONDAY 9 SEPTEMBER 2013, 17:30 PS-1. Ecological consequences of global change in aquatic ecosystems

PS-1.09. OCEAN ACIDIFICATION EFFECT ON MICROBIAL METABOLISM IN TWO DIFFERENT LOCATIONS IN THE MEDITERRANEAN SEA

Mauro Celussi, OGS, Trieste (Italy) Coauthors: Dellisanti W, Del Negro P, Franzo A, Gaubert M, Gazeau F, Giannakourou A, Konstantinopoulou A, Maugendre L, Pitta P, Tsiola A

Ocean acidification (OA) is a process caused predominantly by dissolution of anthropogenic CO2 in seawater and has the potential to affect microbial metabolism. Notwithstanding the increasing amount of researches on this topic no consent has emerged on the effect that OA can have on many prokaryote-mediated processes. In the framework of the MedSeA (MEDiterranean Sea Acidification in a changing climate) project for the first time 2 mesocosm experiments have been performed in coastal Mediterranean areas characterised by different trophic status (ultraoligotrophic Bay of Calvi - Corsica and oligotrophic Bay of Villefranche-sur-Mer). Several parameters were studied along with time in 9 enclosures: 3 unamended controls and 6 CO2 treated ones, with initial pCO2 of 450, 550, 650, 750, 1000, 1250 µatm. Here we present results involving prokaryotic standing stocks and heterotrophic production, abundance of highly respiring cells (CTC+), degradation processes (beta-glucosidase, chitinase, protease, lipase and alkaline phosphatase) and respiration rates. Abundances of heterotrophic and photoautotrophic (Synechococcus) prokaryotes were not affected by CO2 addition in both experiments. Similarly, no evident response to acidification was observed either in CTC+ cell abundance or 3H-leucine uptake rates. Plankton community respiration did not evidently respond to acidification. Degradation of polysaccharides was inhibited by CO2 addition in both experiments whereas lipase activity didn’t show any clear dependence on treatments. The other tested enzymes behaved differently in the 2 sites: mobilisation of aminosugars (by chitinase) was unaffected by acidification at low nutrient concentration whereas it was inhibited in the Villefranche experiment. Alkaline phosphatase and leucine aminopeptidase activities did not show any CO2-related variation in the oligotrophic site. On the contrary, in the Bay of Calvi they were slightly enhanced and inhibited, respectively. Although many fundamental processes did not show clear alteration due to increased pCO2 in seawater, modified degradation rates may affect considerably the export of organic matter to the seafloor and thus ecosystem functioning along the whole water column. Our results highlight the need to further analyse the consequences of OA in different Mediterranean ecosystems in order to predict more precisely the potential damage of anthropogenic CO2 emission on marine resources.

122 MONDAY 9 SEPTEMBER 2013, 17:30 PS-1. Ecological consequences of global change in aquatic ecosystems

PS-1.10. INVESTIGATING A MARINE ALGAL-BACTERIAL SYMBIOSIS FOR ELEMENTS OF THE B- VITAMIN COMPLEX

Matthew Cooper, University of Cambridge - Department of Plant Sciences (UK) Coauthors: Peaudecerf F, Croze O, Goldstein RE, Smith AG

An estimated half of all microalgal species require an exogenous source of vitamin B12 (Croft et al 2005), which has been shown to be important limiting factor of algal growth in oceans and in algal blooms (Koch et al 2011). Previous work in our laboratory has demonstrated an algal-bacterial symbiosis between the B12-dependent green alga Lobomonas rostrata and the soil bacteria Mesorhizobium loti in which bacteria provide B12 in return for fixed carbon from the alga (Kazamia et al 2012). We have now been able to establish a similar symbiosis between the marine alga Ostreococcus tauri, which requires both B12 and B1 (thiamine) for growth, and the bacterium Dinoroseobacter shibae. We show that D. shibae can form a stable interaction with O. tauri in B12 and thiamine limited conditions resulting in mutually supported growth that persists over multiple generations and sub-cultures. This mutualism persists even in media containing no B-vitamin supplements, which is notable as D. shibae requires an exogenous source of biotin, niacin and p- aminobenzoic acid (along with carbon) for growth. This work then shows a complex interaction between these two wide-spread and ecologically relevant organisms in which both provide different elements of the B-vitamin family to support each other’s growth. Using fluorescence microscopy, soft agar capillary assays and microfuidic chamber experiments we also describe the chemotactic behaviour of D. shibae towards the various B-vitamins and potential carbon sources it requires, along with its chemotactic behaviour towards immobilised O. tauri cells. This work has important implications for carbon and nutrient cycling in the world’s oceans along with providing an explanatory mechanism for the widespread evolution of vitamin auxotrophy in many microalgal species. Croft, M. et al. Nature, 438, 90-93 (2005) Kazamia, E. et al. Environ. Microbiol. 14, 1466 (2012) Koch, F. et al. Limnol. Oceanogr. 3, 1023-1034 (2011)

123 MONDAY 9 SEPTEMBER 2013, 17:30 PS-1. Ecological consequences of global change in aquatic ecosystems

PS-1.11. SEAWEEDS FROM UNITED ARAB EMIRATES COASTS AS A NUTRIENT BASE FOR HALO- TOLERANT MARINE BACTERIA AND ACTINOMYCETES TO PROMOTE THE GROWTH OF THE SEAWATER-IRRIGATED OILSEED HALOPHYTE SALICORNIA BIGELOVII

Khaled El-Tarabily, University of United Arab Emirates, Al-Ain (UAE) Coauthors: Alkhajeh AS, Torky Y

Seaweed extract prepared from different green (Cladophora sp.), red (Laurencia sp.) and brown (Padina sp. and Sargassum sp.) algae collected from the Arabian Gulf Coast in the United Arab Emirates (UAE) was evaluated as a nutrient base to promote the growth of the halophyte plant Salicornia bigelovii by halo-tolerant marine bacteria and actinomycete isolates. These marine halo- tolerant isolates were isolated from the mangrove Avicennia marina sediment in the UAE. Twenty- four isolates were selected from a screening of 87 isolates based on their ability to produce plant growth regulators (PGRs). Seventeen promising PGRs-producing isolates were further screened for their competence as root colonizers and for their abilities to colonize Salicornia roots. Five isolates showing exceptional rhizosphere competence which were capable of producing the highest levels of auxins, gibberellins and cytokinins significantly colonized Salicornia roots using the indicator root colonization plate assay and the non-sterile sand tube method assay. These five promising isolates were further tested under greenhouse conditions in seawater-irrigated pots as plant growth promoters in the presence and absence of seaweed extract compared to the commonly used inorganic chemical fertilizers. The nutrient contents, types and levels of PGRs in tissues of treated Salicornia plants were assayed to determine the basis of growth promotion. The treatment which included all five rhizosphere-competent isolates in soil amended with seaweed extract was significantly superior to all other treatments in promoting Salicornia growth. These marine bacteria and actinomycete isolates utilized seaweed extract as a source of nutrients and precursors for PGRs. The endogenous levels of PGRs in Salicornia tissues following combined treatments of the marine actinomycete and bacterial isolates and seaweed extract were found to be significantly enhanced over other treatments. The effect of the seaweed extract appears to be more related to its role as a nutrient base for the bacterial and actinomycete isolates rather than to the increased activity of the general microflora of treated soil. These results indicate that the successful treatment (combination between seaweed extract from the Arabian Gulf coast and marine actinomycete and bacterial isolates as a source of PGRs) can be effective and economical for improving the growth of the halophyte plant Salicornia bigelovii in the UAE coasts.

124 MONDAY 9 SEPTEMBER 2013, 17:30 PS-1. Ecological consequences of global change in aquatic ecosystems

PS-1.12. ANTIMICROBIAL RESISTANCE OF ESCHERICHIA COLI ISOLATED FROM WATERS AND SANDS AT TROPICAL MARINE RECREATIONAL BEACHES IN BRAZIL

Ana Julia Fernandes Cardoso de Oliveira, UNESP, São Vicente (Brazil) Coauthors: Andrade da Costa V, Pinto Bartelochi A

Density, distribution and antimicrobial resistance of bacteria Escherichia coli were evaluated in seawater and sands from two marine recreational beaches with different levels of pollution on the southeast coast of the state of São Paulo (Brazil). At the beach with higher degree of pollution (Gonzaguinha), water samples presented the highest densities of E.coli and higher frequency of resistant strains (69.2%) compared to wet (58.8%) and dry (45.5%) sand from the less polluted beach. Resistance to a larger number of antimicrobial groups was observed in water (betagalactamics, aminoglycosids, macrolides, rifampicins and tetracyclines) and sand (betagalactamics and aminoglycosids). In water samples, highest frequencies of resistance were obtained against ampicilin (23.1%), streptomycin (15.0%) and rifampicin (15.0%), whilst in sand, the highest frequencies were observed in relation to ampicilin (21.5%) and streptomycin (11.0%). At the less polluted beach, Ilha Porchat, highest densities of E. coli and higher frequency of resistance were obtained in wet and dry sand (54.5% and 53.8% respectively) compared to water (50%). Antimicrobial resistance in strains isolated from water and sand only occurred against betalactamics (ampicilin and amoxicilin plus clavulanic acid). The frequency and variability of bacterial resistance to antimicrobials in marine recreational waters and sands were related to the degree of fecal contamination in this environment. These results show that water and sands from beaches with a high index of fecal contamination of human origin may be potential sources of contamination by pathogens and contribute to the dissemination of bacterial resistance.

125 MONDAY 9 SEPTEMBER 2013, 17:30 PS-1. Ecological consequences of global change in aquatic ecosystems

PS-1.13. BACTERIAL UTILIZATION OF TERRESTRIAL ORGANIC MATTER IN AN INFLUENCED BY HIGH INFLOW OF ALLOCHTHONOUS ORGANIC MATTER

Daniela Alejandra Figueroa, Umeå University (Sweden) Coauthors: Rowe O, Paczkowska J, Andersson A

The Bothnian Bay (northern Baltic Sea) is a brackish water body that is highly exposed to terrestrial organic matter (TOM). Here, bacterial production constitutes as much as 50% of the annual basal production, suggesting that TOM to a large extent fuels the marine food web. In our study we examined the extent to which TOM could support heterotrophic bacterial production in a Bothnian Bay estuary (Råne estuary) over spatial and temporal scales. Bacterial growth, dissolved organic carbon (DOC) and its bioavailability, and a range of possible explanatory variables were measured in a transect from within the Råne river to ~6 km offshore, on four occasions between May and August, 2011. Bacterial growth was found to be highest in May, coinciding with the river spring flush, and lowest in August. Linear regression indicated that ~50 % of the overall bacterial growth could be explained by variations in suspended particulate organic material. DOC concentrations were generally highest in the river during spring, ~12 mg C/l and lowest in the most offshore localities, ~5 mg C/l. DOC availability and bacterial growth efficiencies, measured in bioassays performed over 10-14 days, averaged around 8% and 40%, respectively. The average bacterial production in the estuary was 6.2 μmol C L-1 day-1. Thus carbon utilization would have been 15 μmol C L-1 day-1, while the availability from DOC would have been ~6 μmol C L-1 day-1. This indicated that available terrestrial DOC accounted for ~40 % of the bacterial food resource, a finding which is in keeping with other studies indicating a dominance of terrestrial DOC in the Bothnian Bay. Results from our bioassays furthermore showed that bacterial growth were mainly C limited in the estuary, however at the outermost stations, N and P were observed to be limiting. This might be explained by geochemical precipitation of P in the estuarine salinity gradient. Overall, this study indicates that terrestrial dissolved and particulate organic carbon may contribute with as much as 90% of the food source for bacteria in the Råne estuary, the remainder probably originating from autochthonous primary production. With the climate change, the inflow of terrestrial organic matter is expected to increase by ~30% to this sea area. This points at an increased importance of terrestrial organic material as a food source for basal marine production in coastal areas of the Bothnian Bay.

126 MONDAY 9 SEPTEMBER 2013, 17:30 PS-1. Ecological consequences of global change in aquatic ecosystems

PS-1.14. POPULATION TOXICITY OF THE CYANOBACTERIUM PLANKTOTHRIX RUBESCENS IN A PREALPINE LAKE

Marie-Ève Garneau, University of Zurich (Switzerland) Coauthors: Posch T, Pernthaler J

The filamentous cyanobacterium Planktothrix rubescens produces potent toxins called microcystins (mcy) that are toxic to most eukaryotes, from zooplankton grazers to cattle and humans. P. rubescens occurs in many deep and thermally stratified lakes throughout Europe, including Lake Zurich where it re-appeared in the 1970's after a period of re-oligotrophication. Since then, P. rubescens is the dominant species in this major water reservoir of Switzerland, and forms massive blooms in the metalimnion during late summer. To better assess the potential toxicity of these metalimnetic blooms, we quantified the non-mcy-producing filaments of P. rubescens using a qPCR assay that targets a deletion on the mcyH and mcyA genes of the mcy gene cluster. This mcyHA deletion inactivates the microcystin biosynthesis. Two complementary qPCR assays were used to assess the total population abundance (based on the 16S rDNA gene) and the mcy gene copy number (based on a conserved region in the adenylation domain of the mcyB gene). The specific objectives were to evaluate (1) the seasonal patterns and (2) the vertical spatial variations in the proportions of non-mcy-producing filaments in the total P. rubescens population. Samples were collected from July 2011 to March 2013 at three functional depths, i.e. surface (0.5 m), metalimnion layer (ca. 11 m) and below the metalimnion (between 20 to 100 m). Results showed that mcyHA mutants were usually present in low proportions (up to 20%) throughout the year and water column. Highest proportions of mcyHA mutants occurred during the winter mixis, when total abundances of P. rubescens were minimal. The mcy deficient mutants seemed to survive better in sparse populations, maybe because there is then less grazing pressure and thus a reduced need for the protection that is provided by the mcy toxin. The mutants also appeared to cope with the sub-optimal, stressful conditions in terms of light and pressure that are experienced during the winter mixis.

127 MONDAY 9 SEPTEMBER 2013, 17:30 PS-1. Ecological consequences of global change in aquatic ecosystems

PS-1.15. BACTERIAL COMMUNITIES ASSOCIATED TO THE TOXIC DINOFLAGELLATE OSTREOPSIS CF. OVATA DURING BLOOM DEVELOPMENT

Flavio Guidi, Centro Interdipartimentale di Ricerca per le Scienze Ambientali, Università di Bologna (Italy) Coauthors: Vanucci S, Pistocchi R, Guerrini F, Pezzolesi L, Long RA

Diversity of bacterial communities associated with the toxic benthic dinoflagellate Ostreopsis cf. ovata were investigated at a site named Passetto located along the Ancona coast (43°30’ N and 13°37’ E; Northwestern Adriatic Sea; Italy) and characterized by rocky bottom and shallow waters. Ambient seawater samples (< 0.5 m depth) and dinoflagellate-colonized macrophytes were collected at two different stages of the O. cf ovata bloom. Different bacterial assemblages were separated by samples’ fractionation to observe subtle changes within each partition. Among others, free-living seawater community, aggregates/mucilage associated community, and single O. cf ovata cell associated community were considered. Abundances of O. cf. ovata cell were two fold higher at the peak sampling (Oct 2, 2012; 20.6 × 103 ± 28.5 × 103 cells g-1 of fresh macrophyte) than at the beginning of the bloom (Sep 18, 2012; 94.9 × 103 ± 5.88 × 103 cells g-1 fw). Bacterial cell abundance of the aggregate fractions (range: 3.06 × 106 to 6.62 × 106 cells ml-1 ; 1st and 2nd sampling respectively) and aggregate virus-like particle concentrations (range: 1.10 × 108 and 1.23 × 108 VLP ml-1) showed significant correlations with cell densities. The number of bacterial cells attached to the single O. cf. ovata cells was generally low (mean: < 2 bacteria, with a range from 0 to 5 bacteria). Bacterial communities associated to the different fractions were compared using automated rRNA intergenic spacer analysis (ARISA) and results were summarized by similarity based analysis and ANOSIM test. Pyrosequencing analysis was performed for taxonomic affiliation. Among the 178 operational taxonomic units (OTUs) detected, only 11 were present in all samples. Unique OTUs were mainly observed in relation with the aggregate fraction and with single algal cells. Large dissimilarity was found between seawater free-living and aggregate-associated bacterial community structures, either within or between samplings. Interestingly, microbial consortia associated with single O. cf. ovata cells were significant different from communities associated with all the other partitions. On the whole, a total of 409 taxonomic affiliations bacterial genera distributed over 21 phyla were found.

128 MONDAY 9 SEPTEMBER 2013, 17:30 PS-1. Ecological consequences of global change in aquatic ecosystems

PS-1.16. METABOLIC ECOLOGY AND THE RESPONSE TO TEMPERATURE OF MARINE PLANKTONIC BACTERIA IN TEMPERATE WATERS

Huete-Stauffer TM, Coauthors: Arandia-Gorostidi N, Morán XAG, Díaz-Pérez L

The Metabolic Theory of Ecology (MTE) links the biology of individual organisms to the ecology of populations, communities and ecosystems. It is a quantitative theory that predicts how metabolic rates vary with body size and temperature, thus becoming of great importance in the context of global warming. In order to test its applicability to bacterioplankton, we carried out monthly experiments of the temperature response of coastal bacteria over a whole annual cycle during 2012 in the southern Bay of Biscay. The experimental design included 2 treatments, 0.8 µm filtered water to avoid predation (F) and non-filtered water (C), incubated at 3 temperatures (in situ, -3ºC, +3ºC) under saturating irradiance at in situ photoperiod. We analyzed by flow cytometry the abundance, size and biomass of cells with intact membranes (live), actively respiring (CTC+) and the widespread groups of low and high nucleic acid (LNA and HNA), which allowed us to estimate the growth rates and activation energies (E) of these physiological groups. Marked seasonal patterns were found for most environmental conditions, such as temperature (12.7– 21.2ºC), bacterial abundance (0.17–1.10 106 cell ml-1) or chlorophyll concentration (0.14–1.55 µg l- 1), greatly affecting monthly responses. Growth rates ranged between 0.1 and 2.6 d -1. The average E was 0.53 ± 0.05 eV, for live and 0.50 ± 0.06 eV for CTC+ cells, slightly below the mean value proposed by the MTE (0.65 eV). Neither the initial abundance nor the growth rate determined the maximal abundance reached or carrying capacity (K), which was however strongly associated with the initial percent contribution of HNA cells (r=0.87, p<0.001, n=216), overall ranging from 22.7 to 97.9%. Apparent E values of live cells in the F treatments decreased significantly with in situ temperature (r=-0.62, p=0.03, n=12), likely due to substrate limitation during summer as evidenced by a concurrent positive association of E with chlorophyll as a proxy of trophic state (r=0.65, p=0.02, n=12). Our results suggest that increases in growth rate and ultimately abundance due to increasing temperatures in the future ocean will be strongly dependent on the availability of substrates for bacterial growth and metabolism.

129 MONDAY 9 SEPTEMBER 2013, 17:30 PS-1. Ecological consequences of global change in aquatic ecosystems

PS-1.17. EFFECTS OF VARYING OXYGEN CONDITIONS ON ORGANIC MATTER REACTIVITY AND MARINE BENTHIC MICROBIAL COMMUNITIES

Gerdhard L Jessen, Max Planck Institute for Marine Microbiology, Bremen (Germany) Coauthors: Lichtschlag A, Donis D, Wenzhöfer F, Schubert CJ, Ramette A, Pantoja S, Boetius A

Global warming and eutrophication promote in aquatic systems with repercussions on fluxes of energy and matter, and negative effects on ecosystem diversity and function. We investigated the effects of varying oxygen conditions on organic matter reactivity and marine benthic microbial communities at the Crimean Shelf (Black Sea). To inquire this complex unresolved issue, sampling was performed during expedition MSM 15-1 with the R/V Maria S. Merian along an oceanographic transect subjected to oxygen concentrations between 0-150 µmol/L and a spatial gradient in biogeochemical conditions. To test the hypothesis that variations in oxygen supply will cause shifts in the structure and function of microbial communities and reactivity of organic matter, sediment microbial communities were analyzed using ARISA (Automated Ribosomal Intergenic Spacer Analysis) and 454 massively parallel tag sequencing (MPTS). In parallel, the distribution of sediment biogeochemical parameters and hydrolysable amino acids were measured to assess the lability of organic matter and to determine the connections between oxygen supply, benthic microbial community structure and organic matter reactivity. Comparing oxic, hypoxic and highly dynamic hypoxic zones at the Crimean Shelf, abundance determined by acridine orange direct counting, showed similar distributions in the sediment, whereas more organic matter accumulates under variable to low oxygenation regimes. Similarly, bacterial community dynamics observed by changes in OTU (operational taxonomic units) number and occurrence based on ARISA, showed an increase in richness and unique OTUs, with decreasing oxygen availability. Under variable oxygen concentration, however, a more heterogeneous community structure was detected compared with stable oxic and hypoxic conditions. Overall, selective preservation of organic matter was found in areas characterized by dynamic or permanent hypoxia, together with shifts in microbial community structure, and was accompanied by changes in biogeochemical function. Results from 454 MPTS analysis for Bacteria and Archaea will be further presented, to identify key microbial populations resilient to oxygen variation, and on the potential role of the rare biosphere on the observed patterns. This study was supported by the EU 7th FP project HYPOX with additional funding from the PFB31/2007 Program COPAS Sur-Austral, Chile. GLJ is granted a student scholarship from CONICYT, Chile.

130 MONDAY 9 SEPTEMBER 2013, 17:30 PS-1. Ecological consequences of global change in aquatic ecosystems

PS-1.18. GREENHOUSE EFFECT ON THE CONTROL OF POPULATION DYNAMICS OF MICROBIAL COMMUNITIES IN COASTAL WATER OF SURUGA BAY, JAPAN THROUGH DILUTION AND FRACTIONATON EXPERIMENT

Kenji Kato, Shizuoka University (Japan) Coauthors: Tuyet DTA, Tanaka T, Nagaosa K, Hao DM

To reveal the impacts of sea temperature rise on microbial communities particularly on pathogenic groups, we measured the bacterial production and death rates and changes in their community structure employing dilution and flactionation experiments designed with different temperature conditions. Three experiments were carried out in August 2011, April and October 2012 for the water taken from one meter depth of Shimizu Bay (35°00’56”N-138°30’58”E), Japan and samples were incubated at in situ temperature together with + 3/5°C and 10°C conditions. The microbial communities were analyzed done at 3 or 4, 6, 12 or 15, 24 hours of incubation. The most rapid increase in bacterial number appeared at the first 6 hours of incubation for all the examined samples. Bottom-up and top-down controls were found at the same time of 6 hour of incubation in both experiments conducted in April and October. Strong impact appeared in both controls when incubated at higher temperatures than at in situ one. The same trend appeared with impact of viral control. The contriribution of gamma-proteobacteria to bacteria at high temperature conditions were higher than those in the samples at in situ temperature. The results suggest that increasing in temperature may lead increasing in production of prokaryote and particularly for gamma-proteobacteria, which includes pathogens that may cause problems in and environmental health.

131 MONDAY 9 SEPTEMBER 2013, 17:30 PS-1. Ecological consequences of global change in aquatic ecosystems

PS-1.19. N-RELATED PROKARYOTIC COMMUNITIES ACTIVITY AMONG SEASONS AND DEPTH GRADIENT DURING A YEAR IN AN ATLANTIC INTERTIDAL Céline Lavergne, LIENSs - La Rochelle University, La Rochelle (France) Coauthors: Agogué H, Beaugeard L, Dupuy C

European intertidal are the seat of high uptake of inorganic nitrogen and phosphate in coastal waters attenuating high loads from the land to the sea. Nitrogen cycle is thus crucial in these shallow environments because this element can influence biological sequestration of CO2 in the ocean. N-related prokaryotic communities (Bacteria and Archaea) enhance nitrogen biodisponibility by remineralization of inorganic nutrients for primary production and are key organisms in these benthic non light limited ecosystems. Our hypothesis is that prokaryotic metabolism is responsible for the variation of N-related reactions among depth and seasons and creates a nutrient gradient in sediment. Reactions implied in nitrogen cycle can thus vary among depth and seasons in sediment mainly thanks to prokaryotic metabolism and create nutrient release gradient. We thus proposed to study the role of bacterial and archaeal communities involved in the nitrogen cycle among depth gradient in an intertidal mudflat during low tide (Brouage mudflat, Atlantic coast). Sediment and biofilm were sampled at each season during a year at different depths: surface (i.e biofilm, first 500µm), 0.5-1 cm, 1-2 cm, 2-5 cm and 5 to 10 cm. For each layer, several abiotic parameters and the N-related active population ratio by molecular analysis was investigated. We used quantitative PCR to quantify N-related genes expression. Active population was identified by reverse transcription quantitative PCR. Targeted genes were bacterial and archeal amoA (ammonia oxidation), nirS and nirK (nitrite reductases) and anammox (anaerobic ammonium oxidation). Abundance of total prokaryotes was determined by flow cytometry analysis and bacterial production was evaluated by radioactive Thymidine (3H) incorporation. Our results confirm that oxygen and light are crucial for prokaryotic activity considering that high differences occurred among depth. A shift seems to appear after 2 centimeters behind the surface when nutrients concentration decreased. Most active populations were recorded between 0.5 and 1 cm below the surface with 26% of anammox genes actively transcribed. Finally, seasonal patterns are difficult to explain but temperature variations appear to be a driving force for prokaryotes activity and abundance.

132 MONDAY 9 SEPTEMBER 2013, 17:30 PS-1. Ecological consequences of global change in aquatic ecosystems

PS-1.20. BACTERIAL AND ARCHAEAL ABUNDANCES IN LAKES OF BYERS PENINSULA, LIVINGSTON ISLAND (ANTARCTICA) AS DETERMINED BY CATALYZED REPORTER DEPOSITION FLUORESCENCE IN SITU HYBRIDIZATION

Valeria Lentini, University of Messina (Italy) Coauthors: Gugliandolo C, Maugeri T, Camacho A, Lo Giudice A, Michaud L

The prokaryotic diversity in Antarctica is surprisingly high, in contrast with the rather poor diversity of plants and animals. To date, microbiological studies carried out in Antarctic environments have been mainly carried out in the marine environment. Only recently, investigations have been extended to continental biomes, with the aim of isolating and evaluating the biotechnological potential of extreme prokaryotes (Bacteria, and Archaea) adapted to life at low temperature (psychrophilic and psychrotrophic). Byers Peninsula is located at the western end of Livingston Island (maritime Antarctica) and for the natural and biological values, including a large number of lakes, it has been designed as an Antarctic Specially Protected Area (n° 126). The aim of the present study was to evaluate the abundance of Bacteria and Archaea and their relative contribution to the prokaryotic community by using the Catalyzed Reporter Deposition Fluorescence In Situ Hybridization (CARD-FISH) technique. Sediment samples were collected from five lakes (L1, L2, L8, L11 and L15) in the central plateau of the Peninsula, and from two lakes (L5 and L6) located close to the coast, during the 2008-2009 Austral summer, in the framework of the International Polar year. The presence of great colonies of marine fauna greatly influence the trophic condition of coastal waters and of the closest lakes. As revealed by high contents of Chl-a and nutrients, mainly nitrate and phosphates, waters of coastal lakes were eutrophic, whereas those of central lakes were oligotrophic. Total prokaryotic abundance, determined using DAPI (4’, 6-diamidino-2-phenylindole) staining method, ranged from 6.48 × 106 cells g-1 (L8, a central oligotrophic lake) to 1.84 × 107 cells g-1 (L6, a coastal eutrophic lake) and was less than retrieved that from a marine sediment used as control (S1) (2.23 × 107 cells g-1 ). As determined by CARD- FISH technique, microbial communities were always dominated by Bacteria. Bacterial abundance was higher in eutrophic than in oligotrophic lakes. The contribution of Bacteria to prokaryotic abundance was higher in the coastal lakes (from 65.27 to 74.47 % of DAPI-stained cells) than in the central lakes (46.29 to 61.23%). Archaeal contribution to prokaryotic abundance in the lakes, ranged from 0.39 (L11) to 1.21% (L8). Archaea to Bacteria ratio was higher (3:100) in the oligotrophic central lake (L8) than in the other lakes and was also higher than that observed in the control marine sediment (1:100) (S1). Our results suggested that Archaea and Bacteria ratios are strictly determined by the trophic status of lakes. Finally, the low archaeal abundance is in line with previous results, suggesting that they probably do not play a prominent role in the Antarctic lakes.

133 MONDAY 9 SEPTEMBER 2013, 17:30 PS-1. Ecological consequences of global change in aquatic ecosystems

PS-1.21. PACIFIC OYSTER AND ITS MICROFLORA IN CHANGING ENVIRONMENT: TEMPERATURE MATTERS

Ana Lokmer, Geomar - Helmholtz centre for ocean research, Kiel (Germany) Coauthors: Wegner KM

Microbiota play an important role in their host´s life, for good or for bad. Symbiotic bacteria may provide nutrients or protection against disease; they may act as commensals or even turn pathogenic. Which way it will be depends on a number of factors, ranging from host´s genotype, age and physiological condition, to bacterial species composition, and, last but not least, the environment and environmental stress. As diseases represent a strong evolutionary and ecological force, it is important to learn more about conditions leading to them. Temperature is likely to be a major environmental factor shaping the host-microflora interactions in marine poikilotherms, such as the Pacific oyster (Crassostrea gigas). This invasive bivalve has spread across the Wadden Sea in Germany over the last 20 years, partly due to the increase in summer seawater temperatures. If the population will grow further, stabilize or shrink as the warming continues, depends also on the emergence of new pathogens. The first step in adressing this question is to find out more about the oyster microflora in the wild, and how the temperature and biotic and abiotic stress affect its composition and the outcome of oyster-microbiome interactions. Here I will present results from an experiment and a field study tackling these issues with immunological and new-generation- sequencing methods.

134 MONDAY 9 SEPTEMBER 2013, 17:30 PS-1. Ecological consequences of global change in aquatic ecosystems

PS-1.22. MICROBIAL COMMUNITY CHANGES DUE TO CLIMATE CHANGE

Els Maas , NIWA, Wellington (New Zealand) Coauthors: Hulston DA, Burrell TJ, Law CS

Few studies have investigated how bacterial community composition changes in response to climate change, in particular decreasing pH and increasing oceanic temperature. Research to date has shown that microbial communities alter under high CO2 and that the microbial community diverges from the original community. Over the last 5 years we have conducted several experiments in which the pH was altered, either using acid or CO2, and with both pH and temperature were altered in some so that the effect of multiple stressors could be determined. Three experiments were conducted in the Ross Sea, two in oligotrophic water to the north of New Zealand, one in subtropical waters and one in the subtropical front east of New Zealand. The total microbial RNA pool was extracted from these experiments at the start and the end of the incubations and microbial community fingerprints of the active fraction of community using T- RFLP were produced. The general trends observed in the experiments were that microbial diversity decreased under high CO2 conditions and that the community became less diverse compared to the controls. The communities in all incubations diverged from the starting water even in the controls but the communities in the high CO2 incubations in the experiments were more similar to each other than the control. The results indicate that bacterial communities will change under climate change scenario and may become less diverse. This loss of diversity may then alter the functioning of the microbes in the oceans.

135 MONDAY 9 SEPTEMBER 2013, 17:30 PS-1. Ecological consequences of global change in aquatic ecosystems

PS-1.23. ECOPHYSIOLOGICAL ASPECTS OF ALGAL VIRUS-HOST INTERACTIONS IN A CHANGING OCEAN

Douwe Maat, Royal Netherlands Institute for Sea Research, NIOZ Coauthors: Brussaard C

Viruses are an important source of phytoplankton mortality. By lysing their photoautotrophic hosts they directly reduce the available biomass for higher trophic levels. Organic carbon and nutrients are released back into the environment where they are either recycled by microorganisms or exported from the euphotic zone. Both the interaction between viruses and their hosts and the destination of carbon and nutrients is thought to depend largely on environmental factors. The speed by which the world’s oceans are changing, increase the necessity to study these processes in detail. Here we will present different examples of how environmental factors affect the physiology of the ecologically important picophytoplankter Micromonas pusilla and how this in turn has its impact on the viral lytic cycle and consequent production of viruses. We show how elevated pCO2, irradiance availability and nutrient limitation affect the physiology and viral infection of M. pusilla. All factors but pCO2 were found to negatively influence virus-host interaction, whereby co-limitation had the potential to enhance the effect. The consequences of our findings will be discussed in relation to global climate change.

136 MONDAY 9 SEPTEMBER 2013, 17:30 PS-1. Ecological consequences of global change in aquatic ecosystems

PS-1.24. COMPARISON OF THE STRUCTURE OF ACTUAL AND PAST MICROBIAL ASSEMBLAGES IN BENTHIC ARCHIVES OF VILLEREST RESERVOIR (FRANCE)

Benjamin Misson, LMGE, Université Blaise Pascal, CNRS (France) Coauthors: Legrand B, Bonnemoy F, Latour D, Mallet C

In aquatic ecosystems, exploring benthic archives is a pretty good way to study the evolution of microbial communities on large time scales. Such approach can allow us to evaluate their responses to human-induced changes, and the consequences for ecosystem functioning. Villerest reservoir is an artificial dam reservoir established on the Loire River (France) in the early 80’s. To study historical dynamics of its benthic communities, we investigated at first large taxonomic scales by focusing on Bacteria, Archaea and Fungi. Q-PCR analyses revealed similar bacterial and archaeal abundances, whereas fungal communities were far less abundant. Globally, very similar patterns of vertical quantitative variations were recorded for the three communities, and could mainly be attributed to hydrologic events with important decreases recorded in allochtonous deposits (flood or filling of the reservoir). From a qualitative point of view, the different communities all greatly differentiated at the end of the filling of the reservoir, with important shifts of genetic structure. Then, other structural shifts were observed in late 90’s for the bacterial community and a few years later for the archaeal community. Finally, the comparison of such biological data to the global toxicity of the sediment (Microtox® tests) and to concentrations of trace metals and several emerging pollutants enabled us to assess the influence of human activities on microbial assemblages in this ecosystem.

137 MONDAY 9 SEPTEMBER 2013, 17:30 PS-1. Ecological consequences of global change in aquatic ecosystems

PS-1.25. MONITORING THE IMPACTS OF SALTWATER INTRUSION ON SEDIMENT COMMUNITIES

Tiffanie Nelson, Australian Institute of Marine Science, Casuarina (Australia) Coauthors: Streten-Joyce C, Gibb K, Chariton A

Saltwater intrusion into freshwater habitats is occurring on a global scale and is predicted to continue under climate change scenarios. The introduction of saltwater into receiving ecosystems can cause dieback of important vegetation and impact wildlife as has been documented in World Heritage Listed Kakadu National Park, Northern Territory, Australia. There is limited understanding as to the mechanisms underlying the cycling of nutrients in relation to saltwater intrusion. To understand this primary ecosystem response, we investigated the sediment prokaryotic community in relation to salinity. To measure community composition, 16S rRNA pyrosequencing was performed on DNA extracted from 90 soil samples along a salinity gradient from the South Alligator River floodplain in Kakadu. Chemical analyses of the floodplain samples revealed that metal and values differed across sites so the response of the bacterial community could not be directly related to salt exposure. To assess the effect of salt alone, a subset of floodplain soil samples were exposed to freshwater and saltwater under laboratory conditions. DNA was extracted from the laboratory soil samples at three time periods: before, after 48 h and after 7 d. Over 10, 000 different bacterial species were detected in the floodplain soils. Sites with high salinity were less diverse than sites with low salinity. Using data from both the in situ and laboratory study we discuss the importance of prokaryotic communities in saltwater intrusion and the potential effects on biogeochemical cycling.

138 MONDAY 9 SEPTEMBER 2013, 17:30 PS-1. Ecological consequences of global change in aquatic ecosystems

PS-1.26. THE COORONG BACTERIAL METAGENOME REVEALS DRAMATIC SHIFTS IN TAXONOMY AND FUNCTION DRIVEN BY SALINITY

Kelly Newton, Flinders University, Adelaide (Australia) Coauthors: Jeffries TC, Smith RJ, Seymour JR, Seuront L, Mitchell JG

The Coorong estuary lies at the terminus of Australia’s largest river system, the Murray-Darling; both are strongly influenced by human activity. Metagenomic approaches were used to determine the planktonic bacterial community composition and potential metabolic function at two extremes in the Coorong, the river mouth which exhibits marine-like salinity, and the hypersaline upper- reaches of the estuary. Significant shifts in taxa and metabolic function were seen between the two sites. The river mouth exhibited an increase in abundance of Rhodobacteriaceae and Alteromonadaceae; families readily able to adapt to change in nutrient conditions; and the potentially pathogenic families Brucellaceae, Enterobacteriaceae and Vibrionaceae. Metabolisms over-represented include motility and chemotaxsis, RNA metabolism and membrane transport, all of which are involved in actively searching for and obtaining nutrients. Also over-represented were metabolisms involved in population succession and stress response. An over-representation of taxa and metabolisms indicative of environmental change is reflective of anthropogenically affected riverine input. In the hypersaline upper reaches of the estuary the halophilic family Ectothiorhodospiraceae was over-represented as were the families Flavobacteriaceae, Cytophagaceae and Nocardioidaceae, members of which are able to survive over a wide salinity range. Metabolisms over-represented here were reflective of increased bacterial growth, classic of hypersaline environments, and included DNA metabolism, nucleotide and nucleoside synthesis and cell cycle. While the Coorong metagenomes clustered with other planktonic metagenomes they were the least similarity to the group both taxonomically and metabolically, 71 and 84 % similarity respectively. This indicates that Coorong exhibits a unique planktonic bacterial community that is influenced by riverine input at the river mouth and salinity in the upper- reaches.

139 MONDAY 9 SEPTEMBER 2013, 17:30 PS-1. Ecological consequences of global change in aquatic ecosystems

PS-1.27. UV-RADIATION INDUCED DNA DAMAGES IN BALTIC SEA ICE BACTERIA

Jonna Piiparinen, Finnish Environment Institute/ Marine Research Centre, Helsinki (Finland) Coauthors: Pescheck F

The climate change scenarios for the Baltic Sea predict most pronounced air temperature increase in winter time resulting in with a considerable decrease in the extent, thickness and duration of the ice cover. This will affect the light conditions in ice by exposing it earlier in the season and for longer time than in the past and thus, more solar radiation will penetrate into and through the ice. In the microbial food web of sea ice, heterotrophic bacteria play a key role in transforming the dissolved organic carbon to bacterial biomass but ultraviolet radiation (UVR) may disturb this step of carbon transfer in many ways and, consequently, reduce the overall productivity of sea-ice biota. The general acclimation to low light intensities, very limited vertical movement and slower recovery rates at cold temperatures make the sea-ice biota sensitive to UVR as such but as heterotrophic bacteria also lack UV-absorbing compounds (mycosporine-like amino acids) and are small in size, they can be considered to be among the most sensitive ones. Formation of cyclobutane-pyrimidine dimers (CPDs) in DNA is one of the most common direct effects of UVR and unless repaired, these UV-specific damages can be lethal or mutagenic. Although DNA absorbs maximally at 260 nm, the action spectra for DNA dimer induction extends well into UVA region in which most of the ice penetrating UVR wavelengths are in Baltic Sea ice. The aim of this study was to reveal if the earlier observed effects of UVR on bacteria (Piiparinen & Kuosa 2011) could be linked to DNA damages. The data was collected from fast ice in south-west coast of Finland in March 2012. Two untreated (snow-covered and clear ice) and two light-manipulated (PAR and PAR+UVR) ice fields were sampled at the start of the experiment and after 8 days of incubation. Additional samples from clear ice were collected on day 12. In order to estimate the accumulation of CPDs in bacteria vs. bigger organisms, the extracted DNA of size-fractionated (>0.8 µm and <0.8 µm) samples was used for immuno dot plot assay (Boelen et al. 2001). Bacterial production was measured as 3H-thymidine and 14C-leucine incorporation. The preliminary results show that bacterial production was markedly lower under snow-free conditions exposed to full solar spectrum and this was accompanied with a higher number of CPDs. No clear increase of CPDs in the <0.8 µm fraction was observed but this might partly be attributed to methodological deficits as some bacteria were probably trapped in the upper size fraction. These results indicate that UVR plays a significant controlling role in Baltic Sea ice and potentially alters the nutrient and carbon fluxes in the future in the changing climate.

140 MONDAY 9 SEPTEMBER 2013, 17:30 PS-1. Ecological consequences of global change in aquatic ecosystems

PS-1.28. EFFECT OF SOLAR IRRADIATION ON HETEROTROPHIC BACTERIA IN THE MARINE ENVIRONMENT

António Pinto, University of Aveiro (Portugal) Coauthors: Cunha A, Gomes N, Santos E, Almeida A

Photochemical and microbial processes act in concert on carbon recycle and transformation in aquatic ecosystems. Solar radiation induces several dissolved organic matter (DOM) chemical reactions resulting in loss of color and DOM oxidation. These processes also lead to the release of nutrients and to the formation of biological labile compounds, which can increase microbial activity and intensify carbon and energy transformation to trophic webs. The photodegradation processes can result in a transformation of the DOM into a more labile DOM, photoproduction of nutrients such ammonium, nitrates, nitrites and phosphates and therefore increase in bacterial activity and density. The aim of this study was to assess the impact of DOM degradation by solar radiation on bacterial activity and abundance in the marine environment. The study was performed in two distinct locations of Ria de Aveiro (Portugal), one located in the marine zone – N1 - and the other in the brackish water zone – I6. Water samples previously filtered and irradiated in a Solarbox simulator for 12 hours, were inoculated with a bacterial inoculum (1/10) and incubated over one week at in situ temperature in dark conditions. The DOM composition showed a significant change after irradiation in both locations (compared to control, non- irradiated sample), showing a reduction of its molecular weight (E2:E3: 6.8 to 14.0 in N1 and 6.3 to 9.2 in I6), degradation of compounds in bulk DOM (degradation of humic-like compounds – 46% and 60% in I6 and N1, respectively and of protein-like substances – 30% and 47% in I6 and N1, respectively) as well as changes in the nutrient concentration (photoprodution of ammonium in N1; photodegradation of nitrites in both places). A significant increase in bacterial activity and abundance was observed in the irradiated samples relatively to the non-irradiated ones. The results of this study clearly indicate that DOM photochemical reactions lead to formation of compounds that, although might have negative impacts on bacterial communities, their real impact on bacterial activity and density is positive, increasing therefore the ecosystems productivity.

141 MONDAY 9 SEPTEMBER 2013, 17:30 PS-1. Ecological consequences of global change in aquatic ecosystems

PS-1.29. RESPONSES OF ARCTIC BACTERIOPLANKTON ACTIVITY TO OCEAN ACIDIFICATION: RESULTS FROM A MESOCOSM STUDY IN A HIGH LATITUDE FJORD

Judith Piontek, GEOMAR Helmholtz Centre for Ocean Research, Kiel (Germany) Coauthors: Borchard C, Sperling M, Schulz K, Brussaard C, Riebesell U, Engel A

The Kiel Off-Shore Mesocosms for Future Ocean Simulations (KOSMOS), consisting of 9 mesocosm units, were deployed in Kongsfjorden (79°N), on the west coast of Spitsbergen, during June and July, 2010. Each mesocosm enclosed about 45 m³ of seawater with minimal disturbance of the water body and its natural plankton community. The plankton community in the mesocosms was exposed to different CO2 concentrations, ranging from glacial to projected mid-next-century levels. Seawater acidification enhanced the activity of extracellular enzymes. Rates of β-glucosidase and leucine-aminopeptidase increased along the CO2 gradient in the mesocosms and almost doubled when pH was decreased by 0.5 units. Both composition and production of bacterioplankton were closely coupled to phytoplankton productivity throughout this experiment. Bacterial growth started to increase in response to rising chlorophyll a concentrations after a lag phase of only a few days. Comparison of CO2 treatment revealed significantly higher primary production in high- CO2 mesocosms. Elevated primary production under high-CO2 coincided with enhanced bacterial biomass production, suggesting that bacterial carbon turnover can counteract surplus photosynthetic carbon fixation in the future, and, thereby, limit the potential for biological uptake of anthropogenic CO2 in the Arctic Ocean.

142 MONDAY 9 SEPTEMBER 2013, 17:30 PS-1. Ecological consequences of global change in aquatic ecosystems

PS-1.30. OFF-SITE IMPACTS OF AGRICULTURAL COMPOSTING: ROLE OF TERRESTRIALLY DERIVED ORGANIC MATTER IN STRUCTURING AQUATIC MICROBIAL COMMUNITIES

Emma Rochelle-Newall, Institut de recherche pour le développement (IRD), Paris (France) Coauthors: Pommier T, Bettarel Y, Got P, Janeau JL, Jouquet P, Merroune A, Thu TD, Toan TD

Organic amendments such as compost and biochar are considered to provide a sustainable, low cost option for improving soil quality and increasing soil sustainability. However, the impact of these amendments on downstream aquatic ecosystems remains poorly studied, particularly in tropical regions. Here, we present the results from a study conducted in Vietnam that investigated the impact of different organic amendments (compost, vermicompost and biochar) on the quantity and quality of dissolved organic carbon (DOC) in soil leachate and its impact on downstream aquatic microbial communities. The results show that the addition of organic amendments to soil significantly increased the amount of DOC and colored dissolved organic matter (CDOM) lost in leachate and that this organic matter was highly bioavailable to aquatic bacterial communities (up to 27% remineralised in 72h). The addition of biochar to composted material had no impact on the quantity and quality of leachate relative to compost or vermicompost alone. This is in contrast to leachate from soil amended with biochar for which an increase of bioavailability relative to leachate from soil alone was observed. This increase (8% more carbon remineralised than in soil alone leachate) may be due to the stimulation of organic matter upon addition of organic matter ("priming effect"). The addition of terrestrially derived water soluble DOC also resulted in strong shifts in aquatic bacterial diversity as estimated by pyrosequencing. In conclusion, we suggest that the addition of organic amendments, such as compost and vermicompost, to soils has a strong effect on downstream aquatic microbial diversity and that the off-site impacts of these amendments need to be taken into account in agricultural management programs.

143 MONDAY 9 SEPTEMBER 2013, 17:30 PS-1. Ecological consequences of global change in aquatic ecosystems

PS-1.31. SEASONAL DYNAMICS AND INTER-ANNUAL CHANGES OF PELAGIC BACTERIAL COMMUNITIES

Stefan Rösel, Leibniz-Institute of Freshwater Ecology and Inland Fisheries, Stechlin (Germany) Coauthors: Grossart HP

Recurrent seasonal patterns of bacterial abundance and diversity have been observed in long-term studies of marine and freshwater habitats, but the underlying mechanisms are still largely unknown. In order to evaluate seasonal and annual changes of pelagic bacterial communities in different limnetic ecosystems in relation to changes in environmental conditions, we conducted several surveys differing in duration and temporal resolution. First, a long-term study was conducted in mesotrophic Lake Tiefwaren, NE-Germany, ca. 100 km north of Berlin. The lake was sampled monthly for >7 years following a lake restoration treatment. The aim of the long-term monitoring was to determine various limnetic (physico-chemical and biological) variables and microbial parameters for studying succession of the bacterial community in relation to seasonal changes. Second, in a field campaign with a high temporal resolution in oligotrophic Lake Stechlin, we investigated the dynamics of pelagic bacteria during and after the diatom spring bloom. Thereby, changes in bacterial community composition were related to the phytoplankton spring succession. Third, we differentiated between particle-associated (PA) and free-living (FL) bacterial communities to account for different bacterial life-styles. While the free-living bacterial community remained very stable over multiple years, particle-associated bacteria were much more dynamic and diverse. Thus, particle-associated bacteria showed pronounced seasonal trends, whereby summer and winter bacterial assemblages clearly differed from each other. In addition, particle-associated microorganisms were much more variable and tightly coupled to phytoplankton development. Generally, abundance and community composition of both bacterial size fractions were greatly influenced by various environmental variables, most strongly by temperature, pH and nutrient availability (particularly nitrogen and phosphorus). In conclusion, the linkage between long-term studies on multi-annual data and short-term experiments with a high temporal resolution enabled us to evaluate seasonal changes in bacterial communities in detail and to link recurrent seasonal patterns in bacterial community structure to specific environmental factors.

144 MONDAY 9 SEPTEMBER 2013, 17:30 PS-1. Ecological consequences of global change in aquatic ecosystems

PS-1.32. DIVERSITY OF VIBRIO SPP. AND PATHOGENIC VIBRIO SPECIES IN THE CORAL OCULINA PATAGONICA

Esther Rubio Portillo, Universidad de Alicante (Spain) Coauthors: Penalver C, Yarza P, Gomariz M, Martinez-García M, Ramos-Esplá AA, Antón J

Bleaching and other diseases of corals, which can be caused by microbial pathogens and environmental stress, have increased during the last few decades. In the Mediterranean Sea, the pathogen Vibrio mediterranei has been identified as a bleaching agent in Oculina patagonica while Vibrio corallititycus causes disease in the purple gorgonian Paramuricea clavata. In this work we have investigated the relationships between environmental variables and the temporal variation of Vibrio spp. populations in Oculina patagonica, in the Western Mediterranean Sea. We have collected coral colonies and samples of surrounding water, every three months during a year, in two different locations of Alicante coast: Alicante harbour and the Marine Reserve of Tabarca, between 3-5 m depth. Vibrios were isolated from the mucus and the coral tissue by cultivation on TCBS agar. Identification was carried out by sequencing of 16S rRNA genes PCR amplified from genomic DNA of the colonies grown in TCBS. The obtained sequences were compared with reference sequences at NCBI by BLASTn and grouped into phylotypes, defined by sequence similarities ≥98 % using RDP. The occurrence of Vibrio spp. at the seasonal scale was correlated with temperature; in seawater, vibrios were only detected in warm months, but they were present all year-round in corals, although their concentrations were low during cold months. A total of 272 isolates, grouped into 17 phylotypes, were analysed and differences in their distribution were related to trophic status (sedimentation rate, mud fraction and organic matter) and seawater temperature. During late summer and early autumn, when seawater temperature was up to 28ºC, Oculina patagonica showed visual signs of bleaching in both localities, but in Tabarca most of affected colonies exhibited patchy or complete tissue loss. Culturable Vibrio counts in corals during bleaching were higher in diseased (1, 07 x 105 ± 2, 1 x 104) than in healthy (1, 1 x 103 ± 1, 1 x 102) corals. Furthermore, Vibrio communities revealed a perfect grouping by bleached and healthy corals. The pathogens V.mediterranei and V. corallititycus were only present in unhealthy corals; being the former more abundant in the Harbour, and the second in Tabarca. Three phylotypes (V. gigantis, V. harveyi-like and V.comitans) appeared along the whole year in both localities and most likely were part of the normal coral microbiota.

145 MONDAY 9 SEPTEMBER 2013, 17:30 PS-1. Ecological consequences of global change in aquatic ecosystems

PS-1.33. CULTIVATION OF BACTERIA INVOLVED IN THE TERRESTRIAL DOC DEGRADATION ALONG THE SALINITY GRADIENT OF THE BALTIC SEA

Julia Simon, Leibniz-Institute DSMZ, Braunschweig (Germany) Coauthors: Overmann J

The Permafrost of the northern hemisphere has accumulated a large amount of terrestrial dissolved organic carbon (tDOC). As a consequence of the climate change and the melting of the permafrost soil, the tDOC is increasingly mobilized and enters marine habitats. Understanding the degradation of tDOC is needed to identify its feedback on the climate. In the present study, tDOC degradation mechanisms were studied in the Baltic Sea because its salinity gradient covers nearly limnic to marine conditions, allowing the analyses of tDOC degradation under different environmental conditions. Long-term incubation experiments were established with water from the Kalix River (next to Överkalix, North Sweden) as a tDOC source. The effect of salinity on tDOC degradation was studied by using Baltic Sea water with three different salinities (32 g l-1, 7 g l-1 and 2 g l-1) as inoculum. To analyze seasonal tDOC degradation effects the experiment was performed in winter 2011 and in summer 2012. To isolate the relevant bacteria, samples were taken during different stages of tDOC degradation. The MultiDrop technique was used for high throughput cultivation. Changes of cultivability of potential tDOC degrading bacteria were quantified with the most probable number method. First results show a higher cultivability of bacteria with salinities lower than 7 g/l. For the winter experiment the cultivability reached up to 17% of the total bacterial cells, in summer the cultivation successes could catch 25% of the total bacterial cells. The community composition of cultivable bacteria was assessed by DGGE-fingerprinting of 16S rRNA genes. Based on the DGGE-fingerprinting differences in the cultured bacterial community can be shown between the winter and summer experiments. The community in the summer experiment seems to be more diverse than in the winter. First sequence analysis of the winter experiment show Proteobacteria and Bacteriodetes as the most abundant cultured phyla. Also phyla like Acidobacteria, which are known as one main soil phyla, were cultivated. Acidobacteria and Bacteriodetes are also known for degrading terrestrial or complex organic compounds. Further physiological characterizations will be done to understand the roll of the potential tDOC degrading bacteria.

146 MONDAY 9 SEPTEMBER 2013, 17:30 PS-1. Ecological consequences of global change in aquatic ecosystems

PS-1.34. MICROBIAL BIODIVERSITY OF SUB-GLACIAL BRACKISH WATER LAKE: PANGONG TSO

Ram Nageena Singh, National Bureau of Agriculturally Important Microorganisms, Maunath Bhanjan (India) Coauthors: Singh RP, Srivastava AK, Arora DK, Srivastava AK, Sharma AK

Pangong Tso is an endorheic lake in the Himalayan valley situated at a height of about 4, 350 m (14, 270 ft), in Leh-Laddakh, India. It is 134 km long and 5 km wide and extends from India to Tibet and first trans-boundary wetland in South Asia. During winter, the lake freezes completely, despite being saline water. The brackish water of the lake is devoid of any micro-vegetation. There are no reports yet for presence of fish or other aquatic life in the lake, except for some small crustaceans. However, some species of scrub and perennial herbs that grows in the marshes around the lake. The lake acts as an important breeding ground for a variety of birds including a number of migratory birds. During summer, the Bar-headed goose and Brahmini ducks are commonly seen here. It is first study of microbial biodiversity of Pangong Lake by metagenome sequencing analysis. Water sample was collected in frozen state. Whole metagenome sequencing was done by 454 pyrosequencing and analyzed. The analysis of metagenome was achieved by MG-RAST online server which includes RDP, Greengenes, SEED, KEGG and customized curated databases developed by MG-RAST research group. RDP analysis with 90% similarity results in 5 classes Actinobacteria, Aquificae, Proteobacteria, Bacteroidetes and Firmicutes of Bacterial domain while M5NR classification results in Archea (Crenarchaeota and Euryarchaeota), Bacteria (Acidobacteria, Aquificae, Bacteroidetes, Chlorobi, Chloroflexi, Cyanobacteria, Deferribacteres, Deinococcus- Thermus, Fibrobacteres, Firmucutes, Gemmatimonadetes, Lentisphaerae, Nitrospirae, Planctomycetes, Proteobacteria, Spirochaetes, Tenericutes, Verrucomicrobia and unclassified Bacteria), Eukaryota (Ascomycota, Cholorophyta, and Streptophyta) and results in 51 classes with 60% and unassigned sequences. Analysis revealed that sequence data have signatures belonging to 241 genera and 397 species in the sample processed. Greengenes annotation showed one more class Synergistia, which was not shown in either RDP or M5NR. Functional analysis of sequences based on SEED database revealed that major part of the data classified as Protein metabolism, RNA metabolism, Carbohydrate metabolism, DNA metabolism, and stress metabolism, suggested that these are main functions operating in the environment, followed by CO2 metabolism. The study revealed the diversity and presence of some ancient microorganisms in Pangong Lake and will be helpful in deciphering the phylogenetic linkages among the similar ecosystems of world.

147 MONDAY 9 SEPTEMBER 2013, 17:30 PS-1. Ecological consequences of global change in aquatic ecosystems

PS-1.35. CONCENTRATION OF NUTRIENTS FROM LAKEWATER AND ITS APPLICATION TO BARREN LAKESIDE AREA WITH RHIZOBACTERIUM TO PROMOTE REVEGETATION WITH ASTER SP.

Hong-Gyu Song, , Kangwon National University, Chuncheon (South Corea)

Many large barren lakeside areas are formed due to various reasons including climate change, and these areas need revegetation by cost effective and environment-friendly means and a microbial revegetation can be a good alternative. In this study, growth limiting nutrients in oligotrophic lakewater, such as N and P were concentrated in situ in a coconut fiber mat, and the effects of application of the withdrawn nutrient concentrated interstitial water together with a rhizobacterium on growth promotion of a wild plant Aster koraiensis was examined at the barren lakeside area at Lake Paro, S. Korea. Arthrobacter woluwensis ED was isolated from the rhizosphere of a wild plant Isachne globosa. A. woluwensis ED could improve the root length, shoot length, and dry weight of A. koraiensis by 18.6, 22.8 and 26.2%, respectively compared with those of the uninoculated control in a microcosm study, and this wild plant can be used as a pioneering plant species on a barren areas. When the nutrients concentrated lakewater was supplied biweekly to A. koraiensis in a field test, it could increase the lengths of stem and root of grown plants by 4.0 and 35.8%, respectively compared to those of the control (unconcentrated lakewater supplied). The inoculation of A. woluwensis ED (1011 cells/1×1 m plot) with the nutrients concentrated lakewater could enhance the lengths of plant stem and root by 22.4 and 9.4%, respectively than those of uninoculated and concentrated lakewater supplied plot. It showed even higher increase of plant growth compared to those of unconcentrated lakewater supplied control. After 165 days of experimental period, all the plants were harvested and the fresh weight of whole plants and dry weight of subterranean stems were measured. Nutrient concentrated lakewater could not increase the fresh weight of whole plant and subterranean stem of A. koraiensis, but it increased the dry weight of subterranean stem by 16.9% than the control. Simultaneous application of the bacteria and concentrated lakewater showed very high increases of fresh weight of whole plant, fresh and dry weight of subterranean stems. When the bacterial community in rhizosphere soils was analyzed by DGGE, the inoculated bacteria remained more than 2 weeks and there was not any significant change in indigenous bacterial community. These results suggest that a plant growth promoting rhizobacterium A. woluwensis ED may be utilized as biofertilizer for the revegetation of barren lands, especially for sensitive areas such as lakeside lands, and the supply of the nutrients concentrated lakewater can increase its effect further.

148 MONDAY 9 SEPTEMBER 2013, 17:30 PS-1. Ecological consequences of global change in aquatic ecosystems

PS-1.36. INTERPLAY OF BACTERIA AND ORGANIC GEL PARTICLES AT THE AIR-SEA INTERFACE: EFFECTS ON OCEAN CARBON DYNAMICS IN A CHANGING CLIMATE

Christian Stolle, Leibniz-Institute for Baltic Sea Research Warnemuende, Rostock (Germany) Coauthors: Galgani L, Endres S, Schulz KG, Engel A, Jürgens K

The impact of gelatinous, organic particles - like transparent exopolymeric particles (TEP) and Comassie-stainable particles (CSP) and associated bacteria on marine carbon cycling is well established. Furthermore, possible changes on this interplay due to climate change (ocean acidification, increasing water temperature) have been reported. However, less is known how this interaction affects organic matter exchange between the ocean and atmosphere. Thereby, the sea-surface microlayer (SML) - a gelatinous boundary layer at the air-sea interface plays a pivotal role, and our previous studies indicated the importance of particle-attached bacterial communities (i.e. the bacterioneuston) to understand SML dynamics. However, consequences of changing climate on SML structure and function are unclear. Our objectives were to examine the gelatinous composition of the SML as well as the abundance and carbon production of the bacterioneuston community in the future scenario of an acidified ocean. Therefore, Kiel Off Shore Mesocosms for Ocean Simulations (KOSMOS) were deployed in the Raunefjorden, Norway in May 2011, which were exposed to increasing levels of pCO2. The temporal variability of the SML was studied in six mesocosms during a spring phytoplankton bloom for 30 days. In the SML, CSP were found to be more abundant than TEP and both particle types showed different temporal dynamics throughout the experiment. CSP reached highest abundances in the SML four days after the phytoplankton bloom peaks. In contrast, TEP in the SML showed a somewhat variable behavior. Interestingly, the TEP dynamics were clearly correlated to bacterioneuston abundance and production. Whether this was due to upward transport of TEP-attached bacteria from the water column or bacterioneuston TEP production is currently unclear. Nonetheless, the importance of particle turnover in the SML was supported by our findings that particle-attached bacterial production was on average 50 % higher in the SML compared to the underlying bulk water. The different behavior of gel particles in the SML might be at least partially due to bacterioneuston-mediated transformations as revealed by pH-dependent shifts: in higher pCO2 -levels TEP and bacterial abundance in the SML tended to increase whereas CSP and bacterial production tended to decline. Taken together, this study stresses the role of SML functioning in marine carbon cycling and in mediating air-sea interactions in future ocean scenarios.

149 MONDAY 9 SEPTEMBER 2013, 17:30 PS-1. Ecological consequences of global change in aquatic ecosystems

PS-1.37. DIVERSITY OF AQUATIC HYPHOMYCETES IN HANUMANA GUNDI FALLS OF CHIKMAGALUR DISTRICT, KARNATAKA, INDIA

Hombale R Suresha, Kuvempu Unversity, Shivamogga (India) Coauthors: Krishnappa M, Descals E, Raju GH, Taylor BR

Aquatic ecosystems include both fresh and marine water bodies comprising both abiotic and biotic components. The biotic component consists of producers, consumers and decomposers. Microorganisms play an important role in decomposition of organic matter; in fresh water much of this decomposition is carried out by a group of Deuteromycete fungi known as aquatic hyphomycetes. The diversity of aquatic hyphomycetes in a river can be assessed indirectly because they produce distinctively shaped conidia that persist in the water and are often concentrated in foam. Production of conidia may also be induced by incubating decomposing organic matter. The present study was carried out to explore the diversity of aquatic hyphomycetes on leaf bits in Hanumana gundi Falls, located at Chikmagalur District of Karnataka. The fallen leaves of four species of riverside plants were incubated in the falls, collected after 15 days, and examined for the presence of aquatic fungi. A total of 18 species of aquatic hyphomycetes belonging to 13 genera were recorded. There was little evidence of species associations, and the assemblage at each site along the falls was distinct.

150 MONDAY 9 SEPTEMBER 2013, 17:30 PS-1. Ecological consequences of global change in aquatic ecosystems

PS-1.38. THE DEGRADATION OF BIO-PLASTIC BY MARINE MICROBES

Tinkara Tinta, National Institute of Biology, Ljubljana (Slovenia) Coauthors: Glava N, Kovac N, Turk V

One of the major ecological threads for seas and oceans nowadays is marine littering. The central aim of this research was to study the biodegradation of a specific type of edible and biodegradable plastic (bio-plastic), developed to decrease the litter in the marine ecosystem, with the focus on the role of the microbial community in this process. A series of laboratory experiments was set up in small bottles by exposing a piece of soft plastic to different microplankton community size fractions: (a) 0.2 µm pre-filtered seawater (SW) fraction, (b) GF/F pre-filtered SW fraction (presumably containing microorganisms of app. < 0.8 µm in size) and (c) unfiltered SW. Each of the set up was regularly sampled for bacterial abundance and community structure analyses. At the same time samples for FTIR and elemental analyses were collected. The intense degradation of studied substrate was indicated by decreasing absorption intensities of aliphatic CH3 and CH2 stretching (2800-3000 cm-1) and ester C=O stretching (1755 cm-1). In order to determine how the microbial community composition changed during the degradation process, the bacterial community DNA was extracted and 16S rRNA gene clone libraries were constructed. Our preliminary results show that degradation process was slow, on the time scale from weeks to months in the unfiltered SW treatment, while in the treatments containing 0.2 µm and GF/F microplankton size fractions, the degradation of plastic did not start even after several months. The analysis of 16S rRNA gene clone libraries from unfiltered SW treatment showed that most of the clones (app. 33%) are affiliated with Alphaproteobacteria (within which Rhodobacteraceae, Rhodospirillaceae and Hyphomonadaceae), followed by otherwise rare community members Firmicutes (Clostridiaceae), which represented up to 24% of total bacterial community, but were previously not detected in clone libraries from this environment (Tinta 2011). Deltaproetobacteria represented around 12% and Gammaproteobacteria only up to 3%. A large percentage of clones (app. 27%) did not affiliate with any of the sequences deposited in the GeneBank (NCBI). These preliminary results suggest a large possible impact of bio-plastic on the ambient bacterial community structure and consequently on the ecosystem functioning.

151 MONDAY 9 SEPTEMBER 2013, 17:30 PS-1. Ecological consequences of global change in aquatic ecosystems

PS-1.39. INTEGRATED EVALUATION OF ENVIRONMENTAL PARAMETERS INFLUENCING VIBRIO OCCURRENCE IN THE COASTAL NORTHERN ADRIATIC SEA (ITALY)

Ilaria Trento, University of Verona (Italy) Coauthors: Caburlotto G, Bianchi F, Socal G, Lleo MM

There is no general agreement on which parameters determine the persistence and abundance of vibrios in the marine environment, partly because they influence Vibrio occurrence differently in different areas of the world. Moreover, oceanographic parameters are generally interdependent and should not be considered separately when their influence on bacterial presence and concentration is tested. In this study, an integrated approach was used to identify key parameters determining the abundance of Vibrio spp in marine samples from the Venetian lagoon in Italy, which is an important area for fish farming and tourism. Multivariate techniques have been adopted to analyze the data-set: using PCA, it was shown that a relatively high proportion of the total variance in this area was mainly due to two independent variables, like salinity and temperature. Using Cluster Analysis it was possible to categorize different groups with homogeneous features as regards space (“stations”) and time (“seasons”) distribution, as well as to quantify the concentrations of the environmental variables and Vibrio abundances in each categories. Furthermore, integrating key environmental factors and bacterial concentration values, let us to identify levels of salinity and sea surface temperature which were optimal for Vibrio concentration in water, plankton and sediment samples. The identification of key environmental variables conditioning Vibrio occurrence should facilitate ocean monitoring, making it possible to predict unexpected variations in marine microflora which determine possible public health risks in coastal areas.

152 MONDAY 9 SEPTEMBER 2013, 17:30 PS-1. Ecological consequences of global change in aquatic ecosystems

PS-1.40. STUDYING ORGANIC POLLUTANTS AND SEDIMENT BACTERIA IN TEMPORARY AQUATIC ENVIRONMENTS: THE RESULTS OF A MULTIPLE APPROACH

Annamaria Zoppini, Water Research Institute - National Research Council (IRSA-CNR), Montelibretti, Roma (Italy) Coauthors: Ademollo N, Amalfitano S, Casella P, Patrolecco L, Polesello S

Flood and drought events of higher intensity and frequency are expected to increase in arid and semi-arid regions where temporary rivers represent either a water resource or an aquatic ecosystem to be preserved. However, these environments are not recognized in most river management policies. In the present study, we applied a multiple approach characterising the variation of two classes of hazardous substances (Polycyclic Aromatic Hydrocarbons, and NonylPhenols) and the microbial metabolic rates, responsible for organic matter mineralization, in river sediments subject to hydrological fluctuations (Candelaro river basin, Italy). A moderate sediment pollution (PAHs range 8-275 ng g-1; NPs range 299-4858 ng g-1) and drastic changes of the contamination patterns were observed, with mobilization under high flow, accumulation during low flow and a drastic reduction of pollutant concentrations under no flow conditions. The microbial metabolic properties at the streambed level (biomass, bacterial C production, extracellular enzymes, community respiration) declined progressively passing from high flow to low flow conditions, but the resident communities showed residual activities in dry sediments, with potential repercussions on the sediment organic matter quality. The chemical and microbiological dynamics should be taken into consideration for a more realistic prevision of the impact of pollutants in temporary aquatic environments.

153 MONDAY 9 SEPTEMBER 2013, 17:30 PS-1. Ecological consequences of global change in aquatic ecosystems

PS-1.41. OCTADECABACTER JEJUDONENSIS SP. NOV., ISOLATED FROM THE JUNCTION BETWEEN THE OCEAN AND A FRESHWATER SPRING

Yong-Taek Jung,Department of Food Science and Biotechnology, Sungkyunkwan University (South Korea) Coauthors: Sooyeon P, Jung-Hoon Y

Soesokkak, which was located at Jeju island of South Korea and designated a Natural Environment Preservation Zone by UNESCO, is a unique place where the ocean and a freshwater spring meet. During a screening of novel bacteria from the junction place, many novel bacterial taxa have been isolated and characterized taxonomically. One of these isolates, designated SSK2-1T, is described in this study, since it was found to be phylogenetically most closely related to the genus Octadecabacter, a member of the Alphaproteobacteria. The genus Octadecabacter was proposed by Gosink et al. (1997, 1998) with the descriptions of two Octadecabacter species, Octadecabacter arcticus (type species) and Octadecabacter antarcticus, which were isolated from sea ice of the Arctic and Antarctica, respectively. Since then, no species belonging to the genus Octadecabacter has been described yet. The aim of the present work was to investigate if strain SSK2-1T represents a third species of the genus Octadecabacter by using a polyphasic characterization including chemotaxonomic and other phenotypic analyses and a detailed phylogenetic investigation based on 16S rRNA gene sequences. The almost complete 16S rRNA gene sequence of strain SSK2-1T determined in this study comprised 1384 nucleotides, approximately 95 % of the Escherichia coli 16S rRNA sequence. In the neighbour-joining phylogenetic tree based on 16S rRNA gene sequences, the type strains of O. arcticus and O. antarcticus clustered by a bootstrap resampling value of 100 % and strain SSK2-1T joined the cluster comprising the type strains of O. arcticus and O. antarcticus by a bootstrap resampling value of 99.3 %. The relationships among strain SSK2-1T and the type strains of O. arcticus and O. antarcticus were also maintained in the trees constructed using the maximum-likelihood and maximum-parsimony algorithms. Strain SSK2-1T exhibited 16S rRNA gene sequence similarity values of 96.5 and 96.8 % to the type strains of O. arcticus and O. antarcticus, respectively, and less than 95.8 % to the type strains of the other recognized species. The major fatty acids (> 10 % of the total fatty acids) found in strain SSK2-1T were C18:1 ω7c (53.6 %) and C16:0 (29.1 %). The phylogenetic data and differential chemotaxonomic and other phenotypic properties of strain SSK2-1T suggest that the novel strain is separate from recognized species of genus Octadecabacter. On the basis of the data presented, therefore, strain SSK2-1T is considered to represent a novel species of the genus Octadecabacter, for which the name Octadecabacter jejudonensis sp. nov. is proposed.

154 MONDAY 9 SEPTEMBER 2013, 17:30 PS-1. Ecological consequences of global change in aquatic ecosystems

PS-1.42. A NOVEL ESTERASE WITH ACTIVITY TOWARD TERTIARY ALCOHOL FROM COMPOST METAGENOME LIBARARY

Chul-Hyung Kang,Department of Food Science and Biotechnology, Sungkyunkwan University (South Korea) Coauthors: Jung-Hoon Y

A novel esterase, EstCS1, was isolated from compost metagenomic library. The EstCS1 composed of 309 amino acid residues with a molecular mass of 34 kDa and showed the highest amino acid identity (47%) to the lipase/esterase from uncultured bacterium (AAS77247.1). The EstCS1 belonged to HSL family of lipolytic enzyme classification proposed by Arpigny and Jaegar, and retained catalytic triad Ser155-Glu255-His285 typical to the α/β hydrolase. The Ser155 residue in the catalytic triad of EstCS1 was located in the consensus active site motif, GXSXG, and conserved HGG(G/A) motif in oxyanion hole of HSL family was found. The EstCS1 exhibited strong activity toward p-nitrophenyl propionate (C3) and caproate (C6), and was stable up to 60°C with an optimal activity 50°C. The maximal activity was observed at pH 8 and stable within pH range of 5 to 10. Interestingly, The EstCS1 showed the ability in hydrolysis of sterically hindered ester linalyl- acetate and remarkable stability in up to 30% (v/v) of water miscible organic solvents. The organic solvent stability and the activity towards esters of tertiary alcohols of EstCS1 make it potentially useful for organic synthesis and related industrial application.

155

TUESDAY 10 SEPTEMBER 2013, 17:30 PS-2. Bacterial diversity: from community composition to community functions

PS-2.01. MICROBIAL COMMUNITY DISTRIBUTION, COMPOSITION AND ACTIVITY IN THE COASTAL AREAS IN THE SOUTHERN TYRRHENIAN SEA

Cecilia Balestra, Stazione Zoologica A. Dohrn, Naples (Italy) Coauthors: Casotti R

Marine heterotrophic bacteria play an important role in structuring marine ecosystems and their functioning. Taxonomic composition of bacterial assemblages, their metabolic activity and their temporal and spatial dynamics in the oceans has revealed to be of major importance for marine ecosystems. In November 2010, 32 stations, in the Gulf of Naples and along the Latium Region coast along coast-offshore transects, were sampled to estimate heterotrophic bacteria and picophytoplankton abundance, bacterial community composition and bacterial metabolic activity. Cell concentrations were estimated by flow cytometry for three main groups of autotrophs (Synechococcus, Prochlorococcus and ) as well as for the heterotrophic bacteria. Prochlorococcus represented the most abundant group of autotrophic picoplankton (on average 1.88x104cell ml-1SD 1.10x104), Synechococcus were on average 1.50x104cell ml-1 (SD 1.07x104) and picoeukaryotes were 7.59x102cell ml-1(SD 6.20x102). Heterotrophic bacteria were the most abundant group on average 6.01x105cell ml-1(SD 3.88x105). At the surface At the surface all the three groups of autotrophs were more abundant near the Sele river (1.98x104cell ml-1, 4.89x104cell ml-1, 3.31x103cell ml-1, Prochlorococcus, Synechococcus and picoeukaryotes, respectively). Heterotrophic bacteria concentration varied from 1.48x105 and 2.17x106cell ml-1 and their distribution followed the coastal offshore gradient with higher concentrations near the rivers confirming their role as remineralizers of organic matter and as nutrient recyclers. Heterotrophic bacteria community composition was analyzed by CARD-FISH. 75% (SD 8.4%) of total cell counts were detected with the EUB 338 probe. The overall most abundant group was α-proteobacteria 56% (SD 6.7). The second group in terms of abundance was Cytophaga-Flavobacterium- Bacteroides 30% (SD 5.4). γ-proteobacteria were on average 22% (SD 5.0). Along the Sarno and the Volturno river Cytophaga and γ-proteobacteria showed an increase from the offshore stations (22% SD 2.1 and 19% SD 1.8 CFB and Gamma, respectively) to the coastal ones (30% SD 1 and 24% SD 2 CFB and Gamma respectively). On the contrary α-proteobacteria showed an opposite trend with higher concentration offshore (55% SD 2.0) and lower near the coast (44% SD 3.2). Among the α-proteobacteria, SAR11 was the most abundant clade (up to 30% of total Eubacteria counts). The less abundant clade in all the stations sampled was Roseobacter (9% SD 3.4). Results of the analyses of the entire dataset on the community composition, the metabolic activity estimated by MAR-CARD-FISH, and the metagenomics comparative analysis from two sites will be discussed with the aim of providing integrated tools for the assessment of biological properties of coastal areas.

156 TUESDAY 10 SEPTEMBER 2013, 17:30 PS-2. Bacterial diversity: from community composition to community functions

PS-2.02. DIVERSITY OF N2 FIXERS IN THE PHYLLOSPHERE OF MEDITERRANEAN , POSIDONIA OCEANICA, AND THEIR SIGNIFICANT ROLE AS SOURCE OF NEW N IN THE COMMUNITY

Nona Sheila Agawin, University of the Balearic Islands, Palma de Mallorca (Spain) Coauthors: Ferriol P, Cryer C, Alcon E, Busquets A, Sintes E, Vidal C, Moyà G

Molecular analysis of nifH genes of epiphytic samples in the phyllosphere of Posidonia oceanica revealed bacterial nifH sequences, closely related to uncultured bacteria, of which the closer cultured relatives (sequence similarity index >75%) were from Prosthecochloris, Desulfurivibrio, Desulfovibrio, Chlorobium and Chlorobaculum genera. These results indicate the occurrence of a larger diversity of epiphytic nitrogen fixers than previously assumed in these environments. We further provide evidence of their significant nitrogen fixation rates, higher than most rates reported in the phyllosphere of tropical . The findings are new and may have important consequences on identification of significant external source of N to support the high productivity of P. oceanica and a link to the unbalanced N budget in the Mediterranean Sea system.

157 TUESDAY 10 SEPTEMBER 2013, 17:30 PS-2. Bacterial diversity: from community composition to community functions

PS-2.03. A MICROCOSM APPROACH TO UNDERSTAND THE RESPONSE TOWARD SALINITY CHANGES OF SEDIMENTARY NITRIFYING COMMUNITIES

Axel Aigle, MIO-Mediterranean institure of Oceanographie, Marseille (France) Coauthors: Zaghmouri I, Militon C, Guasco S, Bonin P, Michotey V

The response of ammonia-oxidizing (AO) community towards different short term scenarios of salinity fluctuations in microcosm was studied. Two types of sediment were retrieved from the same coastal lagoon but with different long term salinity records; SA1 was located in the northern part of the lagoon directly under the inflows of freshwater and encountered on long-term frequent salinity changes; SA3 was located in the southern part of the lagoon mainly influenced by the marine water inflows with a more stable salinity conditions. From 16S ARNr gene barcoding, SA1 appeared less diverse than SA3 although both stations presented 70% of shared OTU. Ammonia oxidizer abundances were estimated by quantifying gene copies of the ammonia monooxygenase subunit (amoA) and their activity by nitrifying rate measurements and by Amo transcripts quantification. AmoA genes were more abundant in SA1 than in SA3 and Ammonium Oxidizing Archaea (AOA) largely dominated communities of both stations. On transcript level, Oxidizing Bacteria (AOB) were the most active at SA1, whereas AOA were the most active at SA3. Nitrifying activity did not follow Amo gene number and was higher at SA3 than at SA1.

158 TUESDAY 10 SEPTEMBER 2013, 17:30 PS-2. Bacterial diversity: from community composition to community functions

PS-2.05. ZONATION OF BACTERIOPLANKTON COMMUNITIES ALONG AGING UPWELLED WATER IN THE NORTHERN BENGUELA REGION

Benjamin Bergen, Leibniz Institute for Baltic Sea Research Warnemünde (Germany) Coauthors: Herlemann D, Jürgens K

Microbial communities are known as important drivers of biogeochemical processes in upwelling systems. However, the dynamics in their community composition is poorly understood. The Northern Benguela upwelling region is characterized by wind driven upwelling and the resulting Ekman offshore transport of nutrient rich water. The aim of this study was to investigate the succession of bacterial assemblages in aging upwelled water from coastal to offshore sites. We sampled surface water (5 and 20 m) at 12 stations along two subsequent transects from the origin of upwelling to a distance of 220 km. For bacterial diversity analysis, the PCR amplicons of the V3- V5 region of the 16S rRNA gene were pyrosequenced whereas catalyzed reporter deposition- fluorescence in situ hybridization (CARD-FISH) is used for quantification of major OTUs. Additionally, bacterial cell numbers were assessed by flow cytometry and bacterial production by 3H-leucine incorporation. After quality filtering and processing of pyrosequencing data, 12, 5627sequences were clustered into 1335 different normalized operational taxonomic units (OTU) using a definition of 97% sequence identity. Community statistical analysis revealed a reproducible zonation along the two transects with four clusters of microbial assemblages at the phylum-level. All clusters consisted of the same taxonomic divisions, but showed strong fluctuations in their abundance. Moreover, k-means clustering demonstrated that seven characteristic patterns in the abundance of independent OTUs could be distinguished. Most patterns were positively or negatively correlated with phytoplankton, indicating oligotrophic and copiotrophic lifestyles. The single most dominant OTU (9 % of all reads) was affiliated with the SAR11 cluster and showed a strong negative correlation with phytoplankton. In contrast, the second most abundant OTU (6 % of all reads), affiliated with the phylum Verrucomicrobia, correlated positively with phytoplankton. Further corroborated by a close relation of bacterial production and phytoplankton abundance, the data show that shifts in the bacterial community composition and activity are strongly driven by the presence and absence of algal substrates and the phytoplankton community composition.

159 TUESDAY 10 SEPTEMBER 2013, 17:30 PS-2. Bacterial diversity: from community composition to community functions

PS-2.06. THE PLANKTONIC FOOD WEB 200 AND 2012 IN RHINE AND MOSELLE

Tanja Bergfeld, German Federal Institute of Hydrology, Koblenz (Germany) Coauthors: Sklorz K, Scherwaß A

The dynamics of phyto-, bacterio-, proto- and metazooplankton were investigated fortnightly from April until October 2000 and 2012 at Rhine-km 590 and Moselle-km 6. The two rivers differ in their water residence time, but also in their nutrient availability and benthic filter feeder density. The Rhine is a fast flowing river with short flow time, while the Moselle is heavily impounded with long flow time. At the same time, the density of benthic filter feeders is higher in the Moselle clearly influencing the planktonic food web. The Chlorophyll a content in the Rhine (mean 3, 3 µg Chla/L in 2000 and 6, 5 µg Chla/L in 2012) is lower than in the Moselle (mean 9, 6 µg Chla/L in 2000 and 7, 3 µg Chla/L in 2012). In 2000 in both rivers, the bacterial size with a mean value of 0.2 µm length was astonishing small, while in 2012 we found larger bacteria. We discuss the influence of the different conditions in the two rivers on the absolute values, but also on the relation of the different components of the planktonic food web.

160 TUESDAY 10 SEPTEMBER 2013, 17:30 PS-2. Bacterial diversity: from community composition to community functions

PS-2.07. INTRIGUING DIVERSITY AMONG DIAZOTROPHIC PICOPLANKTON ALONG A MEDITERRANEAN TRANSECT : A DOMINANCE OF RHIZOBIA

Isabelle Biegala, Mediterranean Institute Of Oceanography, Marseille (France) Coauthors: Le Moal M, Collin H

Although the importance of nitrogen fixation in the Mediterranean Sea carbon and nitrogen fluxes is under debate, the diazotrophs responsible for this activity have still not been investigated in the open sea. In this study we characterised the surface distribution, species richness of unicellular and filamentous diazotrophs by combining microscopic counts with size fractionated in situ hybridization (TSA-FISH) and 16S rDNA and nifH phylogenies. These genetic analyses were possible owning to the development of a new PCR protocol adapted for scarce microorganisms (1 cell ml-1). Diazotrophs community was dominated at 99.9% by picoplankton at low concentration 3.5 cell ml- 1 including small (0.7-1.5 µm, UCYN-A) and large (2.5-3.2 µm, Crocosphaera watsonii) cells. NifH clone libraries were surprisingly dominated by Bradyrhizobium an α-proteobacteria closely related (94%) to a unique group of terrestrial rhizobia known to be able to fix nitrogen freely extra plantae owning to their photosynthetic activity. We discuss the first discovery of C. watsonii and Bradyrhizobium in the Mediterranean Sea, as well as biotic and abiotic factors which may explain their distribution.

161 TUESDAY 10 SEPTEMBER 2013, 17:30 PS-2. Bacterial diversity: from community composition to community functions

PS-2.08. PRESENCE OF FISH, THEIR EVOLUTIONARY HISTORY AND FEEDING HABITS AFFECT AQUATIC MICROBIAL COMMUNITIES - A MESOCOSM STUDY

Helmut Buergmann H, Eawag: Swiss Federal Institute of Aquatic Science and Technology, Kastanienbaum (Switzerland) Coauthors: Sullam K, Aebischer T, Seehausen O, Matthews B

Through eco-evolutionary feedbacks, the genotype of a fish can affect various ecosystem parameters, including nutrient fluxes, prey community structure and dissolved organic materials. We examine if the presence of fish and their evolutionary history might also impact microbial community structure. We use sticklebacks (Gasterosteus aculeatus) from lake and stream environments in Switzerland to determine how fish ecotype (lake vs. stream) alters the microbial community structure within mesocosm environments. We also determine if these effects are plastic and if they persist in environments once the treatment had ceased and a mixed population of lake and stream fish were introduced to that environment. Mesocosms were stocked with adult populations of lake or stream fish that had been reared on pelagic food or benthic food. Additionally, a subset of the 40 mesocosms was not stocked with fish. Over the course of 2 months, various environmental parameters were measured including dissolved organic carbon, chlorophyll A, and macrofauna. Bacterial community composition was also measured using culture independent techniques, and flow cytometry was used to determine bacterial size distribution in the environment. Overall, the presence of fish increased bacterial richness and the proportion of small bacteria in the environment. Additionally, the size structure of the bacteria in mesocosms with fish reared on pelagic-food shifted to larger bacteria. Once the fish were removed and a mixed population of juveniles was introduced, the bacterial richness in the mesocosms evened out. Despite the similar levels of bacteria richness among treatments at the conclusion of the experiment when mixed juvenile populations were present, environments that had previously been conditioned with lake fish reared on a pelagic diet maintained larger bacteria than the other mesocosms at the final sampling point of the experiment. These results suggest that the presence of fish and their rearing and evolutionary history can impact bacterial community composition in the environment.

162 TUESDAY 10 SEPTEMBER 2013, 17:30 PS-2. Bacterial diversity: from community composition to community functions

PS-2.09. STRUCTURE AND COMPOSITION OF THE BACTERIAL COMMUNITIES IN AN ARCTIC GLACIAL FJORD (KONGSFJORD, SPITSBERGEN, SVALBARD ISLANDS)

Conte A, Dept. of Environmental and Biological Sciences, University of Messina (Italy) Coauthors: Papale M, Lo Giudice A, De Domenico E, Michaud L

The present research was aimed at investigating the structure and composition of the bacterial community inhabiting the Arctic Kongsfjorden. Coastal sediment (S) and seawater (W) samples were collected from seven stations along the fjord, from the inlet to the outlet (stations A to E). In particular, three sites (i.e. C1, C2 and C3) next to the research village at Ny-Ålesund were considered. Samples were analyzed by applying two fingerprinting techniques, T-RFLP and ARISA, in addition to the 16S rRNA gene sequencing of bacterial clones. The T-RFLP analysis showed from 33 to 52 T-RFs in water samples and from 20 to 52 T-RFs in sediment samples. Samples DS, ES and C2S (all sedimentary) appeared statistically to be different if compared to the others. The ARISA highlighted a strong difference between seawater and sediment samples, with 70 to 90 and 69 to 94 peaks that were detected, respectively. Based on results from the application of the fingerprinting techniques, 16S rRNA gene clone libraries were constructed for samples (both sediment and seawater) from sites A (at the inlet of the fjord), C1 (in the middle of the fjord and next to the research village) and E (at the outlet of the fjord). The composition of the bacterial communities differed among sites and sample typologies. As an example, the phylogenetic analyses revealed the predominance of the Bacteroidetes (45.9%) followed by the Proteobacteria (29.7%; Gammaproteobacteria -21.6%, and Alphaproteobacteria -8.1%), Actinobacteria (8.1%) and members of the candidate phylum TM7 (8.1%) in sediment from station C1 (C1S). The Deltaproteobacteria, Acidobacteria and Verrucomicrobia totally contributed to the 2.7% of the sequences. Conversely, in seawater samples from station C1 (C1W), the predominance of the Proteobacteria (42.6%) (Alphaproteobacteria - 21.3%, Gammaproteobacteria - 17%, and Betaproteobacteria 4.3%) and Firmicutes (31.9%), followed by the Bacteroidetes (14.9%) was observed. The Actinobacteria, candidate phylum TM7 and Verrucomicrobia represented from 2.1 to 4.3% of total clones. At species level, only Flavobacterium degerlachei strain KOPRI_22212 was common between sediment and seawater communities. Obtained results enlarge the knowledge on the bacterial communities that inhabit cold environments and highlight the influence of glacier on the composition of the bacterial communities.

163 TUESDAY 10 SEPTEMBER 2013, 17:30 PS-2. Bacterial diversity: from community composition to community functions

PS-2.10. EXPERIMENTAL ECOLOGY TO UNDERSTAND MICROBIAL COMMUNITY STRUCTURATION IN BIOTURBATED OIL-POLLUTED SEDIMENTS

Cristiana Cravo-Laureau, Pau University - EEM UMR CNRS IPREM 5254 (France) Coauthors: Stauffert M, Gassie C, Cagnon C, Barantal S, Gilbert F, Militon C, Stora G, Jezequel R, Cuny P, Duran R

Muddy areas and more or less coastal anoxic zones play a key role for maintaining the integrity of estuarine and coastal ecosystems. By their location these areas are frequently exposed to pollutant injury such as oil spills or accidental events and accumulate various pollutants from the continental hydrosystems. Due to their composition (fine silt sediments), actual remediation techniques are not adapted, leading to the accumulation of the pollutants constituting “pollutant reservoirs” that are threats for the ecosystem and the human health as well. Ecosystems such as mudflats are characterized by intensive bioturbation of sediments due to burrowing activities of macrofauna that modify the microbial metabolisms. It is thus essential to consider the bioturbation when determining the impact of oil on microbial communities. An original experimental laboratory device maintaining pristine bioturbated mudflat sediments with tidal cycles was used to simulate an oil spill. Different treatments were applied: addition of standardized oil, addition of the common burrowing organism Hediste diversicolor and addition of both oil and H. diversicolor. A set of chemical and microbial analyses was performed over a nine- month period to monitor i) the removal of petroleum by estimating hydrocarbon contents ii) the macrofaunal reworking activity and iii) the structures and composition of microbial communities. Overall, oiled microcosms showed different microbial communities irrespective of H. diversicolor addition, while similar hydrocarbon removal capacities were observed revealing the functional redundancy. The mechanisms underlying functional redundancy are difficult to study because manipulating microbial communities in the field is problematical. In our study, the addition of burrowing organisms to sediments maintained near-environmental conditions, allowing the manipulation of microbial community structure and composition, thus opening the way for such a study. Omic approaches will provide in-depth characterization of the microbial communities, their adaptation and the metabolic processes involved in hydrocarbon biodegradation.

164 TUESDAY 10 SEPTEMBER 2013, 17:30 PS-2. Bacterial diversity: from community composition to community functions

PS-2.11. IN DEPTH CHARACTERIZATION OF HYDROCARBON-DEGRADATION CAPACITIES OF MARINE SEDIMENT MICROBIAL COMMUNITIES: ADAPTATION, METABOLIC PROCESSES AND INFLUENCE OF OXYGENATION REGIMES (DECAPAGE)

Cristiana Cravo-Laureau, Pau University - EEM UMR CNRS IPREM 5254 (France) Coauthors: Terrisse F, Abella J, Militon C, Cagnon C, Goni-Urriza MS, Dubosq K, Carbon A, Gassie C, Guasco S, Bartolomé M, Stora G, Michotey V, Gilbert F, Ferreira K, Bonin P, Bouyssiere B, Jezequel R, Cuny P, Duran R

Coastlines are subjected to a variety of pollution injuries, predominantly by crude oil from shipping and offshore mining. The damaging effects of such pollutants to the environment and human health coupled with new societal pressures make the restoration of oil-contaminated areas an urgent priority. The in situ treatment methods, which are particularly useful in remote areas where waste management and/or disposal are an issue, are applied to accelerate natural microbial processes that act on the oil. DECAPAGE project focus on microbial communities inhabiting coastal sediments, developing and applying a suite of integrated cross-disciplinary approaches to explore the hydrocarbon degradation capacities, understand the ecology of sediment ecosystems, particularly how the microbial communities degrade and/or detoxify hydrocarbons and how they are affected by the redox oscillations and alternating oxygen supply. Recently, we showed that the effect of petroleum on bacterial communities is enhanced by the presence of burrowing organisms. Indeed, the reworking activity deeply changes the bacterial communities but the overall degradation efficiency is not affected highlighting the functional redundancy involved in hydrocarbons degradation. These results rise up several important questions to understand the mechanisms underpinning the bacterial communities structuring: How microbial communities respond, adapt and degrade petroleum compounds? How the fluctuations of environmental parameters, particularly oxygen oscillations, influence this process? DECAPAGE aims precisely to answer these questions characterizing in depth these bacterial communities and comparing them with those resulting from mechanical reworking that correspond to a mitigation strategy implemented during oil spills. A special interest will be made to the anoxic populations that could be strongly affected by the oxygen oscillation. At the academic point of view, the expected results will allow to understand the adaptation mechanisms driving the reorganization of bacterial communities in response to petroleum. This will help to determine the optimal oxygenation regimes for efficient petroleum degradation, crucial information for the implementation of mitigation strategies.

165 TUESDAY 10 SEPTEMBER 2013, 17:30 PS-2. Bacterial diversity: from community composition to community functions

PS-2.12. TARANTO GULF (ITALY): A CASE OF OIL-SPILL, REMEDIATION STRATEGIES BY THE USE OF BLUE BIOTECHNOLOGIES

Francesca Crisafi, Institute for Coastal Marine Environment IAMC CNR, Messina (Italy) Coauthors: Russo D, Catalfamo M, Genovese M, Denaro R, Genovese L, Giuliano L, Yakimov MM

In April 2012 in the Gulf of Taranto, 20 tons of fuel have leaked from a Panamanian-flagged cargo ship. The intervention strategy followed the approved protocol by the Italian Ministry of Environment:“Piano di Pronto Intervento Nazionale per la Difesa da Inquinamento di Idrocarburi o di altre sostanze nocive causati da incidenti marini”. In this occasion, we collected about 150 lt of the oil-polluted seawater from the area subjected to containment operations. The aim of our study was to design alternative intervention to the use of biocleaning-agent approved by Ministry of Environment, to avoid the addition of substances which are not naturally present in marine environment. For this reason, we considered the natural potential of marine environment in the degradation of pollutant. Over the past few years, a new and ecophysiologically unusual group of marine obligate hydrocarbon-degrading bacteria (OHCB), composed by Alcanivorax, Marinobacter, Thalassolituus, Cycloclasticus, Oleispira and a few others, has been recognized and shown to play a significant role in the biological removal of petroleum hydrocarbons from polluted marine waters. We performed microcosms experiments in 50lt tanks where we have simulated four treatments: a) no-intervention b) biostimulation c) bioaugmentation d) addition of a biocleaning-agent. The treatments were monitored for 14 days by the analysis of the active members of microbial community by means of taxonomic study of 16SrRNA and GC/FID of hydrocarbons. Results showed that the no-intervention strategy allowed the breakdown of 30% of initial amount of pollutant, biostimulation treatment showed the 63% of degradation, bioaugmentation about 80%, while surprising, the use of the biocleaning- agent allowed the breakdown of the heavy fraction while aliphatic components seemed to be uncharged also when we added OHCB consortium. The best performance of degradation was obtained within the microcosm with consortium and nutrient addition which the activity of OHCB was maintained for all the treatment period. During the biostimulation treatment was observed a stimulation of the growth of Marinobacter and Alcanivorax but the performance of degradation was lower respect bioagumentation condition. In conclusion, the present study demonstrates that the use of natural occurring hydrocarbons- degrading bacteria could be a valid approach for the recovery of marine polluted areas with a low environmental impact and low costs.

166 TUESDAY 10 SEPTEMBER 2013, 17:30 PS-2. Bacterial diversity: from community composition to community functions

PS-2.13. ABUNDANCE AND DISTRIBUTION OF BACTERIAL DIMETHYLSULFONIOPROPIONATE (DMSP)-RELATED GENES IN THE PACIFIC OCEAN

Yingshun Cui, Atmosphere and Ocean Research Institute, University of Tokyo (Japan) Coauthors: Suzuki S, Omori Y, Tanimoto H, Kameyama S, Wong S, Ijichi M, Hamasaki K

Dimethylsulfoniopropinate (DMSP) is mainly produced by marine phytoplankton in the ocean. Bacterioplankton in seawater reportedly metabolize this compound mainly through two pathways. In one pathway, dmdA, the most abundant DMSP-related gene in marine bacterial assemblages, mediates DMSP demethylation and transformation to methylmercaptopropionate (MMPA) which is further degraded to methanethiol, acetaldehyde, CO2 and CoA by means of other three genes, dmdB, dmdC and dmdD, . In another pathway, ddd+ genes mediate the cleavage of DMSP to form dimethylsulfide (DMS), a volatile compound and the most important natural source of sulfur in the atmosphere. To reveal abundance and distribution of bacterial DMSP-related genes in relation to DMS and DMSP concentrations in seawater, we have collected 20 different surface water samples; eight samples from the subtropical North Pacific Ocean (NP), seven samples from the subtropical South Pacific Ocean (SP), and five samples from the equatorial Pacific Ocean (EP), during the cruise of R/V Hakuho-maru from December 2011 to March 2012. DMS concentration in seawater was continuously monitored by proton transfer reaction-mass spectrometry (PTR-MS) throughout the cruise. Q-PCR measurements of DMSP-related genes using 8 primer sets covering different genes and their sub-clusters showed that an average of 32.5% bacteria harbored the DMSP-related genes when normalized by 16S rRNA gene copy numbers. The abundance of the dddP gene was relatively high (9.7-22.5%) in the EP samples. Also, unusually high value (31.5%) was detected in the upwelling area of the SP. The dmdA gene pool was consistently dominated by SAR11 sub- clades (C2, D1 and D3 sub-clades). Bacterial communities showed clear difference in DMSP-related gene profiles (relative abundance of several sub-clades of dmdA and dddP) among different water masses (EP, NP, SP and SP upwelling). We found that when the data of the NP and SP subtropical sites were pooled, the abundance of the dddP gene was positively correlated to seawater DMS concentration, suggesting tight coupling between bacterial DMSP cleavage pathways and DMS emission in this area.

167 TUESDAY 10 SEPTEMBER 2013, 17:30 PS-2. Bacterial diversity: from community composition to community functions

PS-2.14. MICROBIAL COMMUNITY DIVERSITY AND FUNCTION IN SEQUENCING BATCH BIOFILTER GRANULAR REACTORS

Francesca Di Pippo, CNR-IRSA Water Research Institute, Rome (Italy) Coauthors: De Sanctis M, Tandoi V, Rossetti S

Sequencing Batch Biofilter Granular Reactor (SBBGR) is a novel and promising wastewater treatment technology, characterized by high treatment capability and low sludge production, where biomass grows as biofilm and compact and dense granules into the packaged bed of the reactor. The system efficiency mainly depends on the composition and activity of its microbial community, clustering in functional groups, that synergistically performs the degradation process. Two SBBGRs were operated under different wastewater recirculation flows through reactor bed (that cause both different hydraulic condition in the system and oxygen supply to the biomass). Fluorescence In Situ Hybridization (FISH) analysis and different microscope techniques were utilized in combination with the traditional activity measurements (i.e., oxygen uptake rate, COD removal efficiency) to link community structure, functional diversity and microbial activity of biomass. FISH data were used to evaluate changes in microbial diversity (Shannon-Wiener Diversity Index, H, and Species Evenness Index, E) in biofilm and granules during reactor operation and to asses microbial distribution within mature granules. Community diversity indices were also evaluated in granules grown at three bed depths (0, 30 and 60 cm). During the whole experimentation, plants were characterized by high efficiency in removing COD (≥95%) and NOx ( ≥80%) due to the simultaneous presence of diverse microbial activities. Aerobic and strictly anaerobic metabolisms (nitrification, denitrification, fermentation, methanogenesis, sulphate reduction) in the system were observed due to the presence of different reaction environments in the reactor’s bed and to the concurrent functional niche diversification occurring in biofilms and in granules that support community diversity and an efficient biodegradation process. FISH analysis allowed to identify about 90% of total bacteria and showed a reduction in species diversity during the experimentation until the reactor reached steady conditions after the formation of mature granules. Microbial diversity of granule communities also slightly increased from the bottom to the top of the bed. Β-proteobacteria, Actinobacteria, Flavobacteria and δ-proteobacteria were the main bacterial phyla present in granules. Most of the β-proteobacteria in granules were identified as functional group of ammonia-oxidizers (only found in granules formed under high recirculation flow conditions), that showed an heterogeneous distribution along the granule, forming clusters separated by interstitial voids and channels. The observed changes in biodiversity over time were mainly due to species composition variations of the methanogenic Archaea (Methanosaeta spp.), sulfate reducing and denitrifying bacteria.

168 TUESDAY 10 SEPTEMBER 2013, 17:30 PS-2. Bacterial diversity: from community composition to community functions

PS-2.15. ISOLATION OF HETEROTROPHIC DIAZOTROPHIC BACTERIA FROM ESTUARINE SURFACE WATERS

Hanna Farnelid, Linnaeus University (Sweden) Coauthors: Harder J, Bentzon-Tilia M, Riemann L

The wide distribution of diverse nitrogenase (nifH) genes affiliated with those of heterotrophic bacteria in marine and estuarine waters indicates ubiquity and an ecologically relevant role for heterotrophic N2-fixers (diazotrophs) in aquatic nitrogen (N) cycling. In this study, N2 fixation was induced in microaerobic or anaerobic N-free media liquid enrichment cultures which were inoculated with surface water from the estuarine Baltic Sea; thereby showing that at least part of the nifH genes detected in situ originate from functional diazotrophs. After aerobic plating of the enrichment cultures or anaerobic agar dilutions, nifH genes were detected in 64 isolates and N2 fixation activity, measured using acetylene reduction, was confirmed for 40 isolates. Two diazotrophic isolates, one γ-proteobacterium affiliated with Pseudomonas and one α- proteobacterium affiliated with Rhodopseudomonas, were shown to represent established members of the indigenous diazotrophic community with abundances of up to 7.9 x 104 and 4.7 x 104 nifH copies L-1, respectively. This study illustrates that fully oxygenated N-replete surface waters harbor functional heterotrophic diazotrophs. The obtained isolates will facilitate future identification of factors controlling heterotrophic diazotrophic activity in aquatic environments, which is a prerequisite for understanding and evaluating their ecology and contribution to N cycling at local and regional scales.

169 TUESDAY 10 SEPTEMBER 2013, 17:30 PS-2. Bacterial diversity: from community composition to community functions

PS-2.16. IDENTIFICATION AND QUANTIFICATION OF HETEROTROPHIC BACTERIA, CYANOBACTERIA AND YEASTS IN SEDIMENTS IMPACTED BY OIL: DETERMINATION OF MICROBIOLOGICAL INDICATORS AND ISOLATION OF SPECIES WITH POTENTIAL FOR BIOREMEDIATION

Ana Julia Fernandes Cardoso de Oliveira, UNESP, São Vicente (Brazil)

The coastal zone is subject to numerous pressures and impacts caused by human activities, including those activities of oil exploration. These activities generate impacts launching in estuaries and other marine ecosystems various pollutants, including hydrocarbons and PAHs (polyaromatic hydrocarbons). The marine environment more affected by hydrocarbons is the sediment since the petroleum products have high density and are generally deposited on the bottom substrate. Some indigenous microorganisms have affinity for hydrocarbons and are capable of degrading these compounds to become numerically dominant in contaminated areas which enable them to be used as indicators of contamination and / or bioremediators. In order to characterize and quantify microorganisms present in estuarine sediments contaminated by hydrocarbons, the densities of cyanobacteria, heterotrophic bacteria and yeasts were evaluated in two Estuaries of the South Coast of São Paulo (Brazil), the Santos Estuary (home to the largest port in Latin America) and the Estuarine System of Cananéia. The numerically dominant genera within each group were isolated to study their potential use as bioindicators and how bioremediators. Sediment samples were collected at three different points in the two estuaries and the densities of microorganisms were determined by direct counting in epifluorescence microscope using DAPI as a dye for heterotrophs. The isolation of heterotrophic bacteria and yeasts were made by the technique of "spread plate" using Marine Agar media for heterotrophic bacteria and Mycosel and Sabouraud (chloramphenicol added) for yeasts. The identification of the microorganisms was made by morphology of strains and traditional biochemical tests. Analyses of hydrocarbons were performed according to the standards of extraction and analysis recommended by the EPA (Environmental Protection Agency). The results showed higher concentrations of hydrocarbons in the samples of Santos estuary (407, 623 and 933 μg g-1, points 1, 2 and 3, respectively) being an order of magnitude higher than values found in sediments of Cananéia.The densities of cyanobacteria and heterotrophic bacteria were higher in sediments of Santos (ranging from 3.21 x 103 to 4.10 x 104 cells ml-1 for cyanobacteria and 4.73 x 104 to 5.34 x 105 cells ml-1 for heterotrophic bacteria) than in the Cananéia sediments. On the other hand, the densities of yeasts were higher in Cananéia (3.91 x 102 to 6.38 x 102 cells ml-1) than in Santos (5.21 x 101 to 7.56 x 101 cells ml-1). The bacterial and yeasts strains isolated are being kept for later identification. The numerical dominance of heterotrophic bacteria and especially of cyanobacteria in estuarine sediment samples with higher concentrations of hydrocarbons indicate that species of these microorganisms can be good indicators of contamination of these environments and that the strains may have potential to be used in bioremediation.

170 TUESDAY 10 SEPTEMBER 2013, 17:30 PS-2. Bacterial diversity: from community composition to community functions

PS-2.17. SEASONAL DYNAMICS IN ABUNDANCE AND DIVERSITY OF AEROBIC ANOXYGENIC PHOTOTROPHIC BACTERIA IN NORTHWESTERN MEDITERRANEAN WATERS

Isabel Ferrera, Institut de Ciències del Mar, Barcelona (Spain) Coauthors: Borrego C, Salazar G and Gasol JM

Aerobic anoxygenic phototrophic (AAP) bacteria are heterotrophic organisms that can derive a portion of their energy requirements harvesting light using bacteriochlorophyll a (BChl a). These organisms can form a significant fraction of bacterial communities in surface marine waters. Attachment to particles, temperature, light attenuation, nutrient limitation or vulnerability to predation have been identified as possible factors controlling their occurrence. Phylogenetically, marine AAPs are diverse consisting of several groups distributed across the α- and γ- proteobacteria. Analyses of puf operon (marker for AAPs) based on the Global Ocean Survey metagenomic data pointed out that AAP genetic diversity changes between different oceanic regions. However, very little is known about their temporal dynamics in marine ecosystems. For this purpose, we studied AAP abundance and diversity throughout a year at the Blanes Bay Microbial Observatory (Northwestern Mediterranean) and explored the links to an array of environmental data. AAP abundance ranged between 1.12x103 and 5.02x104 cells·ml-1 forming 0.25 to 6.31 % of total prokaryotes. Cell numbers were very low from November to March and reached higher values from April to October showing a marked seasonality that correlated positively with day length and light at the surface. BChl a concentration was only detected between April and October and pigment cell quota varied much more than abundance of AAP bacteria. Pyrosequencing of pufM gene resulted in a total of 82 different OTUs (12-36 per sample) belonging to 8 different phylogroups. The most abundant group was by far phylogroup K which contains γ-proteobacteria representatives, followed by phylogroup C which presents no culture representatives. However, striking differences were observed in the relative contribution of the different groups throughout the year. Overall, samples were more diverse in winter than in summer showing an opposite trend to abundance. MNDS plots revealed that samples clustered according to season revealing that there is a natural succession in AAP populations over time. Spearman correlations showed that the environmental variables that best explained the distribution of AAPs at the OTU level were temperature, chlorophyll a and day length. These results highlight that this functional group is highly dynamic and undergoes a clear seasonality in response to environmental conditions.

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TUESDAY 10 SEPTEMBER 2013, 17:30 PS-2. Bacterial diversity: from community composition to community functions

PS-2.18. VERTICAL DISTRIBUTION, ABUNDANCE AND SEGREGATION OF ACTIVE MISCELLANEOUS CRENARCHAEOTIC SUBGROUPS IN LACUSTRINE ANOXIC SEDIMENTS

Mireia Fillol, University of Girona (Spain) Coauthors: Gich F, Cuesta I, Sanchez A, Borrego C

The Miscellaneous Crenarchaeotic Group (MCG) is one of the most diverse archaeal lineages based on its intragroup 16S rRNA phylogeny. MCGs are ubiquitous and abundant in deep subsurface marine sediments but they have also been consistently found in other habitats. Although few data are available on its potential metabolism and ecological role, recent findings suggest that at least some MCG are heterotrophic anaerobes that feed on detrital organic compounds. Notwithstanding this, their widespread occurrence and high phylogenetic diversity might suggest different roles on carbon mineralization. In this study we have combined primers targeting the whole MCG lineage and new primers specifically designed to members of MCG subgroups prevalent in karstic lakes to assess differences in their abundance in different compartments of two stratified lakes of the Banyoles Karstic System (Catalonia, North-East Spain). Particularly, samples from anoxic water layers, biofilms grown on surfaces of vegetal debris accumulated in the sediment and from different layers along a sediment depth profile were analyzed to resolve specific habitat distribution for the different MCG subgroups. Correlation 2– analysis between MCG abundances (DNA and cDNA) and different environmental variables (SO4 , TP, Nitrogen species, TOC, DOC and IC) were carried out to infer links between prevalent MCG subgroups and carbon sources as well as electron acceptors. We also measured the specific UV absorbance (SUVA254) strongly correlated with percent aromaticity of organic compounds to correlate the presence of active MCG subgroups with variations of DOC reactivity. Segregation patterns of MCG subgroups among compartments differing in both physico-chemical conditions and quality of organic matter might suggest distinct metabolic capacities and physiological requirements that eventually affect their habitat distribution and ecological relevance.

172 TUESDAY 10 SEPTEMBER 2013, 17:30 PS-2. Bacterial diversity: from community composition to community functions

PS-2.19. DIFFERENT METHODOLOGIES FOR A BETTER UNDERSTANDING OF THE BACTERIAL DYNAMICS DURING A WASTEWATER TREATMENT BY ACTIVATED SLUDGE

Idoia Garaizabal, University of Basque Country (UPV/EHU), Leioa (Spain) Coauthors: Ziegler A, Arana I, Orruno M, Larsen P, Nielsen P, Barcina I

In an activated sludge wastewater treatment plant, bacteria are by far the most dominant group of organisms in the biological treatment. Many bacteria, and among these many pathogenic bacteria are continuously coming into the plant with the wastewater, but their fate in the plants is largely unknown. Due to these reasons, the study of these microorganisms is so important. However, traditionally this study has been tackled from a quantitative point of view. Currently available methods allow a further study of the bacterial community structure, allowing a qualitative approach. By the combined use of quantitative and qualitative studies, we want to achieve a better understanding of the fate and behavior of bacteria in an activated sludge WWTP. The methods included were: quantification of total bacteria (Acridine Orange), bacteria with intact cytoplasmatic membrane (Live&Dead kit), active Escherichia coli by CARD-FISH), quantification of some culturable populations (heterotrophic bacteria at 36 and 20ºC and E. coli), and determination of bacterial populations by molecular methods, 16S amplicon sequencing and FISH. This study has shown that while the quantitative methods report information about the efficiency of the treatment and the physiological state of some bacteria, the qualitative methods provide data about the succession of bacterial populations along the process. In this point, it has to be pointed out that the bacterial community structure of the influent differed totally from the rest of samples taken along the treatment. While the genera Acinetobacter and Arcobacter represented the 60% of the total population in the influent, a drastic decrease occurred in the effluent, where they did not reach more than 3%. Otherwise, an accumulation and enrichment during the process was seen with bacteria of order Rhizobiales and Burkholderiales, which triplicate its relevance from the influent to the effluent. In conclusion, the combination of several methods allows evaluating not only the efficiency of WWTP functioning, but also the changes that happen in the population during it. This leads us to better understand the risk associated with the discharge of the water in the receiving environment. An accumulation in the sludge of bacteria has been also seen, which would recommend a careful treatment of the solid fractions that are taken out of the WWTP as surplus sludge.

173 TUESDAY 10 SEPTEMBER 2013, 17:30 PS-2. Bacterial diversity: from community composition to community functions

PS-2.20. MICROBIAL COMMUNITY COMPOSITION AND FUNCTIONAL GENE VARIATION WITH DEPTH IN THE DEEP-WATER MASSES FROM THE ATLANTIC

Juan Antonio Garcia, University of Vienna (Austria) Coauthors: Bergauer K, Offre P, Weinmaier T, Schleper C, Herndl GJ

The phylogenetic but particularly the functional diversity of prokaryotes in the deep-water masses of the Atlantic are poorly characterized. To address this lack of knowledge, metagenomic analyses using single-end pyrosequencing and paired-end Illumina sequencing were performed on eight stations in the North Atlantic gyre at six different depths, ranging from the deep euphotic (100 m) to the abyssal zone (5000 m). Distinct water masses were sampled such as the oxygen minimum zone, the North Atlantic Deep Water and the Antarctic Bottom Water. Phylogenetic analyses showed that the microbial assemblages of all metagenomic libraries were dominated mainly by Proteobacteria. Moreover, Firmicutes, Cyanobacteria and Thaumarchaeota contributed to a substantial fraction in surface waters whereas the presence of Actinobacteria, Thaumarchaeota and Crenarchaeota was substantial in deeper waters. Despite these taxonomic differences, each of the communities shared a similar metabolic composition as indicated by the similar percentage of COGs and ORFs involved in the main metabolic pathways. However, substantial differences were detectable in the percentage of some functional genes, mainly related to energy acquisition and membrane transporters among the different depth layers. The percentage of transporters was significantly higher at the base of the euphotic zone than in deeper layers. From the meso- to the abyssopelagic layers, the percentage of transporters to the total number of proteins was rather constant. The number of ORFs related to phosphorus metabolism decreased with depth as well as the number of carboxylases. The percentage of ORFs involved in the nitrogen and sulfur metabolism decreased with depth down to the bathypelagic zone but increased again in the abyssal possibly reflecting the influence of resuspension of bottom sediments or outwelling of N- and S-compounds from the deep sea floor.

174 TUESDAY 10 SEPTEMBER 2013, 17:30 PS-2. Bacterial diversity: from community composition to community functions

PS-2.21. EMERGENCE OF CYCLOCLASTICUS SP. FROM THE RARE BIOSPHERE AS KEY PHENANTHRENE DEGRADER IN PRISTINE AND CHRONICALLY OIL POLLUTED COASTAL SEAWATERS

Jean François Ghiglione, CNRS-Laboratoire d'Océanographie Microbienne LOMIC (France) Coauthors: Sauret C

We coupled DNA-stable isotope probing and massive parallel pyrosequencing to link the bacterial diversity and function of degradation of phenanthrene in three NW Mediterranean coastal sites with various pollution levels. Cycloclasticus sp. was systematically found to be dominant in the 13C- enriched fractions (more than 60%), revealing its pivotal role in phenanthrene degradation whereas it belongs to the rare biosphere in the natural sample. Interestingly, other groups generally found in polluted areas, such as Glaciecola sp., were abundant in the 12C fractions but not found in the 13C fractions, suggesting that these bacteria are opportunist but were not involved in the degradation of this pollutant. This study constitutes a base for the adaptation of DNA-stable isotope probing technique to link diversity and functions in marine environment.

175 TUESDAY 10 SEPTEMBER 2013, 17:30 PS-2. Bacterial diversity: from community composition to community functions

PS-2.22. FIVE LARGE DEEP SUBALPINE LAKES PROVIDE HIGH PROKARYOTIC DIVERSITY IN THE VERTICAL GRADIENT DURING SPRING AND SUMMER

Salvador Hernández, FES Zaragoza, Universidad Nacional Autónoma de México, Mexico City (Mexico) Coauthors: Callieri C, Bertoni R

We studied the prokaryotic assemblages in five subalpine lakes of different trophic conditions and mixing features, situated in Northern Italy and Southern Switzerland. L.Garda and L.Maggiore are both oligotrophic and oligomictic, L.Como is eutrophic and oligomictic, while L.Iseo and L.Lugano are eutrophic and meromictic. In early spring and summer the samples were taken at five depths (3 m, 10 m, 50 m, 200 m and maximum depth) and in situ hybridization (CARD-FISH) carried out using the following probes: Bacteria (EUB I-III), Thaumarchaeota (CREN537), Proteobacteria (ALF968, , BET42a, GAM42a), Cytophaga-Flavobacteria of Bacteroidetes (CF319a), Actinobacteria (HCG69a) and freshwater SAR11-cluster of Alphaproteobacteria termed LD12. In spring, at the maximum mixing, prokaryotes did not exhibit a vertical density gradient in the oligomictic lakes while the percentage of Betaproteobacteria increased with the depth in the meromictic lakes. Noteworthy was the dominance of Alphaproteobacteria in L.Como. In summer the prokaryotic community changed and niche differentiation occurred in almost all lakes: in L.Garda Actinobacteria dominate in the first 10 m and Bacteroidetes in the deeper layers. Actinobacteria dominate also in the first 10 m in L.Maggiore, L.Garda, L.Como, and were absent in L.Lugano and dominant in the whole water column in L.Iseo. Thaumarchaeota were confined to the hypolimnion during summer stratification, but present all over the water column in spring mixing. Uncultured bacteria of LD12-lineage were found in all lakes with higher percentage contributions in the epilimnion. However, in the eutrophic lakes Lugano and Iseo their relative contribution was less than in the oligotrophic lakes.

176 TUESDAY 10 SEPTEMBER 2013, 17:30 PS-2. Bacterial diversity: from community composition to community functions

PS-2.23. SPATIAL AND TEMPORAL VARIABILITY OF BACTERIOPLANKTON COMMUNITY STRUCTURE AND FUNCTION IN THE NORTH-WEST COAST OF THE IBERIAN PENINSULA

Victor Hernando-Morales, Laboratorio de Ecología Marina, Universidad de Vigo (Spain) Coauthors: Balagué V, Salazar G, Gasol JM, Cram JA, Sachdeva R, Needham DM, Fuhrman JA, Varela MM, Teira E

Marine bacteria are important drivers of ecosystem processes. While some studies suggest diversity gradients are minimum or absent in these unicellular organisms, due to their high abundance and high dispersal patterns, environmental factors are known to influence their abundance and ecology. We simultaneously studied bacterioplankton community composition, bacterial production (BP) and bacterial respiration (BR), in relation to environmental factors along an annual cycle at two Atlantic offshore stations in Vigo and A Coruña (NW Spain). Samples were collected at approximately monthly intervals form September 2009 to December 2010, at two irradiance levels (100% and 1% of surface Photosynthetic Active Radiation (PAR)). Both BP and BR were higher from March to October than during the winter at both sampling locations. BP was significantly correlated with chlorophyll-a concentration in Vigo, but not in A Coruña, which suggests a stronger coupling between autotrophic and heterotrophic compartments in Vigo site. Bacterial diversity patterns were assessed by 16S-ITS rDNA clone libraries coupled with automated ribosomal intergenic spacer analysis (ARISA). Sequence data from more than 750 clones allowed assignment of ARISA fragment lengths to the different bacteria developing in this coastal marine environment. We matched circa 85% of ARISA peaks with corresponding lengths from clone libraries. Analysis of ARISA profiles showed greatest similarity between samples both at the surface and depth and between Coruña and Vigo sites during the period of winter mixing. During summer stratification, bacterial communities separated by only 20-40 metres in the vertical direction were more different than those found hundreds of kilometres apart in the horizontal (i.e. between Vigo and Coruña at 100%PAR). Comparison of monthly bacterial community similarities among samples from the same sampling point and depth showed oscillation patterns in bacterial communities along the year. In surface waters (100% PAR), both A Coruña and Vigo communities showed the highest co-occurrence between samples with an 11 months gap (i.e. between January 2010 and December 2010). This seasonal variability was not observed at 1% PAR at either site. Correlation analysis of ARISA profiles and both biological and environmental data, provided insight into the factors influencing the occurrence and abundance of specific groups of bacteria.

177 TUESDAY 10 SEPTEMBER 2013, 17:30 PS-2. Bacterial diversity: from community composition to community functions

PS-2.24. CHARACTERIZATION OF NITRIFYING COMMUNITIES IN BRACKISH RECIRCULATION AQUACULTURE SYSTEMS

Jennifer Hüpeden, University of Hamburg, Biocenter Klein Flottbek, Dep. of Microbiology and Biotechnology (Germany) Coauthors: Spieck E

The worldwide increasing seafood consumption leads to high fishing pressure and resulted in strongly overfished oceans. In this context the use of aquaculture systems gains increasing attention for the production of marine as well as limnic fish and other aquatic animals. The re-use of water via recirculation aquaculture systems (RAS) features an efficient and ecological way of fish farming. The removal of excreted toxic ammonia and nitrite is carried out by nitrifying chemolithoautotrophic microorganisms. Nitrification takes place on biological filters, which are located in well aerated moving bed reactors. Inside these biofilters ammonia and nitrite oxidizing bacteria (AOB and NOB) colonize carrier elements, forming dense biofilms together with heterotrophic bacteria. The sensitive process of microbial nitrification inside these systems, which is strongly influenced by changing environmental parameters, can still be regarded as a black box. So far little is known about the microbial wastewater detoxification in brackish RAS. This study focuses on nitrification with regard to process optimization of different brackish RAS, which are distinguishable in operational parameters such as fish population, feeding intensity, pH and temperature. Although the analyzed RAS were supplied by the same (brackish) water, varying operational parameters might have affected the composition of the microbial community and their metabolic activity in complex ways. Here, two RAS has been analyzed: Trout production was done at a temperature of 17°C and a pH of 7.9, whereas zander farming used 22°C with a pH of 7.4. Community structure of biofilm building AOB and NOB of the different RAS was analyzed via 16S rRNA gene fingerprinting methods. Dominating nitrifying genera of AOB and NOB (Nitrosomonas, Nitrospira, Nitrotoga) were visualized and identified via transmission electron microscopy and fluorescence in situ hybridization, respectively. In future studies qPCR analyses will be applied to delineate species specific expression levels of metabolic key enzymes. Observation of microbial communities and their metabolic activity in RAS gives useful information to control nitrification performance in dependence of the N-load. Therefore, we aim to understand the effects of environmental and operational parameters on the composition of nitrifying community and their functioning in brackish RAS in order to improve sustainability in high-density fish farming.

178 TUESDAY 10 SEPTEMBER 2013, 17:30 PS-2. Bacterial diversity: from community composition to community functions

PS-2.25. BROTHERS, SISTERS AND PHOTOSYNTHETIC BASTARDS OF FRESHWATER GENUS LIMNOHABITANS (BETAPROTEOBACTERIA)

Vojtěch Kasalický, Biology Centre of ASCR v.v.i, Institute of Hydrobiology, České Budějovice (Czech Republic) Coauthors: Yonghui Z, Jezbera J, Simek K, Boldarjeva K, Cuperová Z, Koblizek M

Bacterial photosynthesis represent a widespread phenomenon in aquatic habitats. Recent investigations showed that Rhodoferax-like Betaproteobacteria contribute significantly to the pool of freshwater sequences of pufL, pufM and bchY genes. To resolve their phylogenetic affiliation, we studied available isolated strains of the Limnohabitans genus which has been longtime considered as purely heterotrophic. We found a heterogeneity in the presence or the absence of photosynthetic genes within genus. Strains from lineages LimA, LimC2 and LimC6 completely lack the genes and all photosynthetic cluster. On the other hand, genomic analysis revealed that strains possessing whole photosynthetic cluster are of both types with or without the carbon fixation pathway. The possibility of light energy gain for many members of the genus Limnohabitans is, however, highly questionable because of lack of any pigmentation (BchlA included). So, why do they need it?

179 TUESDAY 10 SEPTEMBER 2013, 17:30 PS-2. Bacterial diversity: from community composition to community functions

PS-2.26. SPATIO-TEMPORAL DYNAMICS OF AEROBIC METHANE OXIDIZING BACTERIAL COMMUNITY AND ITS METHANOTROPHIC PATHWAYS IN THE PELAGIC FOOD WEB OF SUBTROPICAL FEI-TSUI RESERVOIR

Yuki Kobayashi, Academia Sinica, Taipei (Taiwan) Coauthors: Ito M, Kojima H, Lin CHM, Kuo K, Wang KW, Fukui M, Shiah FK, Okuda N

Methane is an important trace gas which is 25-times more effective than carbon dioxide as greenhouse gas. Methane accounts for 20% of current global warming. Recent study suggested that lake ecosystems are the primary source of global methane. However, this estimation could be highly uncertain because how many sub- and tropical lakes emit methane are still unknown. In our previous study, we found that carbon isotope ratio of POM and crustacean meso-zooplankton became extremely depleted in the early winter period with strong vertical mixing. It suggested that methane oxidizing bacteria (MOB) might change seasonally, and their products might be transferred to zooplankton level through microbial-loop processes. However, direct evidence for the presence of MOB and methanotrophic carbon pathways have not available in this reservoir. In this study, water samples of the MOB community and heterotrophic nanoflagellate (HNF) were collected from 6 depths in Fei-Tsui Reservoir from October in 2012. The headspace method was used for methane measurement. Bacteria abundance in water samples and in the food vacuoles of protozoa was traced. The CARD-FISH (catalysed reporter deposition fluorescence in situ hybridization) with total cell counts (with 4’, 6’-diamidino-2-phenylindole [DAPI]) using group- specific oligonucleotide probes (Mγ84, Mγ705 and Mα450) are used to detect type I and II methanotrophs. During the stratification (Nov. and Oct.) period, methane concentrations at 90m depths were 2.5 and 6.4 mmol l-1, respectively. The number of MOB did not show major difference between in two sampling days. However, after Dec., dissolved oxygen concentration increased at the bottom layer and methane concentration was not detectable. Meanwhile MOB abundance in Dec., especially at 0 m depth, increased to 0.9 x 105 cells ml-1 and accounted for 9.5% of DAPI count. Type II dominated (2.8- 17.7% of DAPI) at most sampling depths of all sampling time. As for MOB in HNF, MOB abundance increased during winter vertical mixing. These results indicated that a part of MOB may be transferred from the bottom to upper layer by physical mixing and MOB was detected although methane was not detected there. And the increasing MOB number found in HNF indicated that these HNF may be grazed by upper trophic grazer and as the result, carbon isotope ratio of zooplankton may show extremely depleted. This study has ecological implications for understanding the carbon cycling in lake ecosystems and subsequent trophic transfer toward higher consumers, resulting in reduced methane emission from the lakes.

180 TUESDAY 10 SEPTEMBER 2013, 17:30 PS-2. Bacterial diversity: from community composition to community functions

PS-2.27. ISOLATION OF NEW MARINE BACTERIA USING CULTURE-DEPENDENT AND - INDEPENDENT APPROACHES

Cendrella Lepleux, Leibniz-Institut DSMZ-Deutsche Sammlung von Mikroorganismen und Zellkulturen GmbH (Germany) Coauthors: Overmann J

Among microorganisms, bacteria show the highest diversity. So far this diversity is not sufficiently accessible due to the low cultivation success for most bacteria. This is particularly true for marine samples with low culturability values of sometimes <0.1%. At the same time, the high fraction of physiologically active bacteria in natural marine samples indicate that these bacteria are capable of dividing and that previous cultivation methods are not optimally suited to meet the growth requirements of these microorganisms. We have developed innovative isolation and cultivation approaches in order to tap marine bacterial diversity. The focuses of the current study are three numerically abundant, yet partially understudied groups of marine bacteria, the Alphaproteobacteria, Bacteroidetes and Chloroflexi. Within the framework of the European MaCuMBA project, we assess cultivation protocols targeting members of these groups, combining cultivation-independent and -dependent methods. A suite of deep sea Arctic samples from the water column and sediments were investigated. Firstly, a specific DGGE-fingerprinting based on the 16S rRNA gene and targeting these understudied groups was developed. The newly developed media comprise two oligotrophic growth media, one composed of artificial sea water and trace elements with trace of complex carbon substrates (glucose, peptone and yeast extract), and another composed of 40 defined carbon substrates. These media were then used for high- throughput isolation using the Microdrop technique. The physiological, genomic and proteomic characteristics of the newly isolated strains was then studied according to their specific ecological niche (particularly tolerance of salinity, temperature, carbon sources) in order to optimize their cultivation. The goal of this work was to isolate new marine bacterial strains as a potential source of new active biomolecules (enzymes, antimicrobials, detergents) relevant for medicinal or industrial applications.

181 TUESDAY 10 SEPTEMBER 2013, 17:30 PS-2. Bacterial diversity: from community composition to community functions

PS-2.28. FINE SCALE ANALYSIS OF HORIZONTAL MICROHETEROGENEITY WITH ILLUMINA SEQUENCED 16S RRNA GENES IN A HOT SPRING FROM NORTHERN PATAGONIA

Roy Mackenzie, Institut de Ciències del Mar CSIC, Barcelona (Spain) Coauthors: Corral P, Martin-Platero A, Polz M, Pedrós-Alió C, Díez B

Vertical zonation is a well known characteristic of hot spring microbial mats, in which microbial populations form mat layers that can be distinguished with the naked eye. But little is known about horizontal heterogeneity. We analyzed this microheterogeneity in a hot spring mat from northern Patagonia by collecting 40 samples in a 25 x 10 cm grid, and sequencing 16S rRNA genes with Illumina. Temperature within the grid ranged from 52.4 to 60.2 ºC, and a clear shift in primary producers could be seen, from Cyanobacteria dominating at the lower temperature, to Chloroflexi dominating at the higher temperature. This illustrates the complexity of these apparently uniform mats. Other major bacterial phyla detected were Bacteroidetes, Proteobacteria, Deinococcus- Thermus and Planctomycetes, but no clear patterns were observed along the gradient for these groups. A considerable number of retrieved sequences were not found in databases, suggesting a high degree of novel diversity in these mats.

182 TUESDAY 10 SEPTEMBER 2013, 17:30 PS-2. Bacterial diversity: from community composition to community functions

PS-2.29. SEDIMENTS OF ANCONA HARBOR: IMPACT OF POLLUTION ON BACTERIAL DIVERSITY AND ENRICHMENT OF OIL-DEGRADING BACTERIAL ASSEMBLAGES

Francesca Mapelli, University of Milan (Italy) Coauthors: Magagnini M, Barbato M, Borin S, Daffonchio D

The Mediterranean Sea is one of the hottest oil spill spots in the world due to the intense oil tanker traffic and the high number of extractive platforms, pipelines and refineries settled around the basin coastlines. In addition, several coastal sites are threatened by the strong impact of the anthropogenic activities contributing to the occurrence of a high risk for the marine ecosystems healthiness. The Adriatic Sea, a semi-enclosed basin in the Mediterranean Sea, hosts different vulnerable and contaminated environments, including the Ancona harbour which sediments have been investigated in the present study by cultivation dependent and independent approaches. The analysis of bacterial diversity by DNA-based fingerprinting methods unveiled a different composition of the bacterial communities colonizing contaminated and not contaminated sediments in the Ancona harbour. A distance-based multivariate analysis for a linear model was used to investigate possible links between bacterial diversity and heavy metal concentrations. Results suggest that different pollutants may play distinct roles in controlling bacterial assemblages in sediment layers. Several slurry microcosms with sediments of the Ancona harbour were set up with oil hydrocarbons as the sole carbon source. The aim was to select and identify hydrocarbon degrading bacterial consortia from the autochthonous microbiome of the polluted sediments. Denaturing Gradient Gel Electrophoresis (DGGE) applied on the 16S rRNA bacterial gene revealed that both the site of sediment collection and the supplemented pollutants are involved in the selection of peculiar bacterial communities. Although different bacterial genera were identified by DGGE analysis, isolation efforts led to the obtainment of pure cultures belonging exclusively to the genus Alcanivorax. Additional tests were performed to identify the best conditions for hydrocarbons biodegradation. Overall, the results indicated the polluted sediments of the Ancona harbour as a promising environmental niche for the selection of valuable bacterial resources to be exploited for marine bioremediation. The results demonstrated, moreover, the need of innovative cultivation approaches aimed to obtain in pure culture marine species that showed to be enriched by the presence of pollutants, but were not cultivated in standard laboratory conditions.

183 TUESDAY 10 SEPTEMBER 2013, 17:30 PS-2. Bacterial diversity: from community composition to community functions

PS-2.30. NITRIFICATION IN TEMPERATE AND BOREAL FRESHWATERS: COMMUNITY COMPOSITION, N2O EMISSIONS AND THE ROLE OF WINTER

Roxane Maranger, Université de Montréal (Canada) Coauthors: Massé S, Soued C, Galipeau P, Walsh D, del Giorgio P

Over the last decade, several studies have focused on identifying the diversity of ammonia oxidizers, measuring nitrification rates and nitrous oxide (N2O) in oceanic systems using novel molecular and isotopic tracer techniques. However, to our knowledge no study has looked simultaneously at the diversity and rates of activity of ammonia oxidizing organisms and the production of N2O in lakes. In order to assess the importance of nitrification throughout different seasons, we followed the diversity and measured nitrification rates over an annual cycle in a small temperate/boreal oligotrophic lake. This work was complimented by a broader scale regional study looking at N2O flux from different aquatic ecosystems (lakes, rivers and wetlands) of various boreal regions. For the time-series study, we observed a clear increase in nitrate and N2O concentrations under the ice during the winter. DNA results targeting the functional ammonia monooxygenase gene (amoA) suggested that nitrifying beta-proteobacteria (AOB) were performing this function in winter. Archaea were present but apparently did not possess the amoA gene. Future goals will be to evaluate the quantitative PCR amplification of amoA gene in both AOB and AOA across seasons and compare these estimates to nitrification rates obtained using 15 + NH4 incubations. In terms of N2O flux among systems in the boreal region, differences among regions were observed but lakes consistently emitted more N2O than rivers or wetlands, with the latter acting often as N2O sinks. Here again N2O accumulated under the ice over winter. Interestingly the amount of N2O emitted upon ice-out represented a hot moment of N2O loss- representing approximately 30% of the annual emissions. Our results suggest that nitrification during the winter may be an under appreciated process in aquatic ecosystem functioning.

184 TUESDAY 10 SEPTEMBER 2013, 17:30 PS-2. Bacterial diversity: from community composition to community functions

PS-2.31. DIVERSITY, DISTRIBUTION AND ACTIVITY OF DIAZOTROPHS IN THE TROPICAL WATERS OF NORTH EASTERN AUSTRALIA

Lauren Messer, University of Technology, Sydney (Australia) Coauthors: Mahaffey C, Brown M, Seymour J

The regulation of the oceanic nitrogen cycle is heavily influenced by microorganisms. Nitrogen fixation provides a new source of nitrogen to the euphotic zone through the reduction of molecular N2 to bioavailable ammonium, and is mediated by a diverse yet limited number of microbes termed diazotrophs. In oligotrophic waters nitrogen limitation affects primary production and ultimately the export of organic matter, suggesting an important role for diazotrophs in nutrient poor regions. We investigated nitrogen fixation in the relatively pristine, oligotrophic waters of north eastern Australia during a transit voyage in October 2012. A combined approach was used to assess both the activity and the diversity of diazotrophs across distinct oceanographic regions. Rates of nitrogen fixation varied spatially within surface waters, with a peak in nitrogen fixation in the Gulf of Carpentaria, negligible fixation activity was observed in the Torres Strait, and measurable nitrogen fixation activity was seen in the Coral Sea. We observed a shift in diazotroph activity from surface waters to the deep chlorophyll maximum at one station, to the east of the Great Barrier Reef and west of the Coral Sea Basin, but at all other stations nitrogen fixation at the chlorophyll maximum was insignificant. Initial assessment of the diazotrophic community suggests a differential contribution of distinct diazotroph groups to nitrogen fixation activity. Our results demonstrate that nitrogen fixation is an important process in the oligotrophic waters of NE Australia and highlights the heterogeneous distribution and activity of diazotrophs within this region.

185 TUESDAY 10 SEPTEMBER 2013, 17:30 PS-2. Bacterial diversity: from community composition to community functions

PS-2.32. GUT MICROBIOTA ANALYSIS OF SURGEONFISHES FROM THE RED SEA REVEALS PATTERNS OF CO-EVOLUTION WITH THE GIANT SYMBIOTIC BACTERIA, EPULOPISCIUM

Sou Miyake, KAUST, Thuwal (Saudi Arabia) Coauthors: Ngugi D, Stingl U

Epulopiscium fishelsoni ('Epulos') are unusual intestinal symbionts that inhabit the intestinal tracts of certain Surgeonfish species. Despite possessing an array of interesting characteristics including, large cell size, extreme polyploidy, and ability to release living daughter cells from a mother cell, the lack of available culture has limited the study of these bacteria. While a few studies documented their presence only in the intestinal tracts of Surgeonfish, the possibility of co- evolution with their fish host has never been evaluated. Also, the microdiversity of Epulos and other bacteria in Surgeonfish still remains unresolved. To address these fundamental questions on the gut microbiota of Surgenonfishes, we applied 16S rRNA pyrotag sequencing on nine species of Surgeonfish from the Red Sea. Additionally, specific host-symbiont co-phylogenetic relationships were further studied via comparison of host and symbiont phylogenies with Fluorescent in situ hybridization (FISH) was used to corroborate the phylogenetic and morphological diversity. The results from our study document for the first time that the intestinal microbiota of Surgeonfish are remarkably diverse. More importantly we show that the predominance and occurrence of Epulos is not universal among all Surgeonfishes, and maybe related with the feeding lifestyle of their hosts. Their diversity is also much higher than anticipated, both within a single fish gut and in different fish species. Although phylogenies between the host Surgeonfish and Epulos did not match perfectly, statistical analysis revealed significant pattern of co-divergence. Further investigation on the mode of transmission of Epulos should reveal the true extent of this symbiosis.

186 TUESDAY 10 SEPTEMBER 2013, 17:30 PS-2. Bacterial diversity: from community composition to community functions

PS-2.33. COMPOSITION AND RICHNESS OF ARCHAEA IN SEAWATER, SEDIMENT AND SPONGES IN THE KEPULAUAN SERIBU REEF SYSTEM, INDONESIA

Ana Rita Moura Polónia, Department of Biology, CESAM, University of Aveiro (Portugal) Coauthors: Cleary D, Duarte L, de Voogd N, Gomes N

Coral reefs are among the most diverse and productive ecosystems in the world. Most research has, however, focused on eukaryotic taxa such as corals and fishes. Recently, there has been increased interest in the diversity and composition of prokatyotes, particularly those inhabiting corals and sponges, but these have mainly focused on bacteria. There have been very few studies of coral reef Archaea, despite the fact that Archaea have been shown to play crucial roles in nutrient dynamics, including nitrification and methanogenesis, of oligotrophic environments such as coral reefs. Here, we present the first study to assess Archaea in four different coral reef biotopes (seawater, sediment and two sponge species, Stylissa massa and Xestospongia testudinaria). The archaeal community of both sponge species and sediment was, dominated by Crenarchaeota, while the seawater community was dominated by Euryarchaeota. The biotope explained almost 70% of the variation in archaeal composition. The number of OTUs was highest in sediment and seawater biotopes and substantially lower in both sponge hosts. Dominant taxa (≥ 300 sequences) in both sponge hosts belonged to phylogenetically distinct lineages. No 'sponge- specific' archaeal OTUs were found, i.e., OTUs found in both sponge species but absent from abiotic biotopes. In summary, our study shows that each biotope hosts highly distinct archaeal communities with the greatest species and phylogenetic diversity found in sediment and the least in sponge hosts.

187 TUESDAY 10 SEPTEMBER 2013, 17:30 PS-2. Bacterial diversity: from community composition to community functions

PS-2.34. DIFFERENT LAND USE PATTERNS AFFECT RESPONSES OF RIVER EPILITHIC BIOFILMS: A CASE STUDY IN YASU RIVER WATERSHED, SHIGA, JAPAN

Aya Murakami, Center for Ecological Research, Kyoto University (Japan) Coauthors: Okuda N, Iwata T, Williams R, Nakano SI

What goes on inside epilithic biofilms in rivers and streams has been treated as a black box in the field of ecology even though they are recognized as important basal food sources as well as sinks for nutrients in such systems. However, the advancement in both microscopy and molecular technologies has made it possible to assess microbial community compositions and their activities with respect to their environmental conditions. Yasu River watershed (387 km2) is one of the main watersheds that drain into Lake Biwa, the largest freshwater lake in Japan. Three main adjacent land uses are forests, agricultural fields and urbanized residential areas. For the study, 30 sites were chosen within the watershed with 10 representatives per main land use. Biofilm samples were collected by incubating nutrient diffusive substrates (NDS) at each site for three weeks in Oct-Nov 2012. Four types of NDS were prepared by amending 2% agarose (control: C) with nitrate (N), phosphate (P) or both (NP) and incubated in quadruples. Environmental factors such as discharge, water temperature, openness, as well as amounts of nitrates and phosphates. Extracellular enzyme activities within biofilms were analyzed by using fluorescence-labeled substrates and a microplate reader (Twinkle LB970, Berthold Technologies, Germany). The potential effects of environmental variables including land use on activities of biofilms were assessed by Generalized Linear Mixed Model using “lme4” package of R 3.0.0 (R Development Core Team 2013). Correlation between physicochemical parameters were analyzed prior to GLMM using “stats” package of R 3.0.0 to prevent autocorrelation within models and reduce numbers of parameters. Different land use patterns affected the responses of biofilms’ extracellular enzyme activities against different nutrient amendments in Yasu River watershed. Individual physicochemical parameters (river discharge, openness and N/P ratio) could not explain the variations seen in enzyme activities. However, both nutrient treatments (especially those involving P) and land use patterns explained the variations significantly (ANOVA, Tukey’s HSD, P<0.05). It is possible that the combined complex effects of individual physicochemical factors could not be visualized clearly while land use patterns acted as representatives of multiple factors affecting biofilm activities. Further analyses of community composition using their 16S rRNA are being conducted and we hope to present these results as well.

188 TUESDAY 10 SEPTEMBER 2013, 17:30 PS-2. Bacterial diversity: from community composition to community functions

PS-2.35. TEMPORAL SHIFTS IN BACTERIAL COMMUNITY COMPOSITION IN A SINGAPOREAN RESERVOIR SYSTEM USING 16S RRNA PYROSEQUENCING

Charmaine Ng, Nanyang Technological University (Singapore) Coauthors: Raingeard D, Haller L, Trottet A, Steinberg P, Larsen O, McDougald D

Singapore relies on a comprehensive network of canals to harvest rain and storm water runoffs to 17 reservoirs distributed throughout the island. These water storage reservoirs are reserves for recreational activities, industrial and domestic uses. Current methods for monitoring water quality include routine physico-chemical measurements and the use of biological indicators of Escherichia coli, Enterococcus spp. and fecal coliforms to test for contamination. Microbial communities play important roles in biogeochemical cycling and greatly impacts reservoir water quality. This underscores a need to examine the diversity, composition and distribution of freshwater microbial taxa in Singaporean reservoirs. This work aims to assess the functional gene diversity and temporal variation of microbial community composition in a Singaporean reservoir using the Geochip and tag-encoded 16S rRNA pyrosequencing from sampled biomass over a year (May 2011- April 2012). Sequence data were analysed through MOTHUR while the Ribosomal Database Project (RDP) was used for taxonomic classification. Patterns of changes in microbial community composition were statically validated using PRIMER and dominant members affiliated to Cyanobacteria, Alphaproteobacteria and Bacteroidetes appeared to persist throughout the year. Among the dominant taxa, a bloom of cyanobacteria was observed between February 2012 and April 2012 reflected by a decrease in richness. Cyanobacterial blooms are frequently reported in Singaporean reservoirs and this bloom event was likely attributed to OTUs assigned to Cyanobacteria Gp XI (Microcystis) and Cyanobacteria Gp III (Prochlorothrix). Prior to the bloom event, peaks in abundance of OTUs assigned within Alphaproteobacteria (Roseomonas, Caulobacter genera and the Sphingomonadaceae family) and Bacteroidetes (Flexibacter) were observed, and are likely to be part of a freshwater bacterial consortium associated with cyanobacterial blooms.

189 TUESDAY 10 SEPTEMBER 2013, 17:30 PS-2. Bacterial diversity: from community composition to community functions

PS-2.36. THE IMPACTS OF SULFATE REDUCING PROKARYOTES ON THE DOMINANT METHANOGENIC PATHWAY IN A FRESHWATER WETLAND

Andrew Ogram, University of Florida, Gainesville (United States) Coauthors: Bae HS, Holmes ME, Chanton J

The Florida Everglades, a large subtropical in the United States, is historically phosphorus limited. Runoff from an adjacent agricultural area into sections of the marsh have resulted in a gradient in phosphorus and sulfate concentrations in the water and soil, producing numerous ecosystem level changes. Previous studies have shown that the resident soil microbial communities change along the gradient, including a shift toward hydrogenotrophic methanogens and the hydrogenotrophic methanogenic pathway and away from the acetoclastic pathway in the nutrient impacted soils. Sulfate reducing prokaryotes (SRP) are known to compete for electron donors with methanogens, such that their activities may provide an important control on the structures and activities of methanogens as a function of nutrient impact. To test this hypothesis, we studied SRP activity, changes in mRNA concentrations produced by SRP and specific methanogenic groups, and the methanogenic pathway determined by stable isotope analysis at three sites along the nutrient gradient and in laboratory incubations. The field sites include one that is impacted by the nutrient runoff, another that is unimpacted, and a third (transition) that is midway between the impacted and unimpacted sites and is associated with the moving nutrient front and exhibits certain characteristics of both the nutrient impacted and the unimpacted sites. The nutrient impacted site exhibited higher potential sulfate reduction rates (SRR; 0.48 µmol×g soil-1×d-1) and methanogenesis rates (3.1 µmol×g soil-1×d-1) than the transition site (SRR, 0.003 µmol×g soil-1×d-1 ; methanogenesis, 0.89 µmol×g soil-1×d-1) or the unimpacted site (SRR, 0.03 µmol×g soil-1×d-1 ; methanogenesis, 0.03 µmol×g soil-1×d-1). These potential activities were consistent with RT-qPCR trends for dsrB and mcrA. Lab incubations using an SRP-inhibitor showed a shift toward acetoclastic methanogenesis in the nutrient impacted and transition soils, but relatively little impact in U3, suggesting the SRB in site F1 and F4 are important competitor for acetate with the methanogens. Group-specific RT-qPCR indicated an increase in the activities of Methanosaeta (the dominant acetoclast) in the nutrient impacted and transition soils in the presence of the inhibitor, indicating that SRP compete for acetate with methanogens. SRP appear to be responsible for the shift from acetoclastic methanogenesis toward hydrogenotrophic methanogenesis in nutrient impacted soils of the Everglades.

190 TUESDAY 10 SEPTEMBER 2013, 17:30 PS-2. Bacterial diversity: from community composition to community functions

PS-2.37. THE ROLE OF ARCHAEA IN THE NITROGEN CYCLE OF ESTUARINE SEDIMENTS

Claudia Pala, CNR-ISMAR, Ancona (Italy) Coauthors: Molari M, Tillmann L, Manini E

Estuaries are hot-spots of organic matter and nutrient fluxes between terrestrial and marine aquatic ecosystems. However, the microbial and biogeochemical controls of many of these processes are still poorly understood. In particular, microbial activities in estuaries are important for aquatic nitrogen cycling. In recent years our understanding of the processes involved in the nitrogen cycle and microrganisms that mediate them has been drastically changed. The anaerobic oxidation of ammonia (anammox) as well as the aerobic oxidation of ammonia by Archaea have been discovered as two important new elements of the global nitrogen cycle. These processes and organisms are widespread both in terrestrial and marine ecosystems. The niche partitioning between aerobic ammonia oxidizing Bacteria (AOB) and Archaea (AOA) is currently understood to be controlled mainly by availability of ammonium, the trophic status as well as the pH of a given habitat. Here, we challenge current perspectives by showing that AOA dominate over AOB in estuarine sediments highly loaded with ammonium, organic matter and at elevated pH (~8.4). We have analysed the abundance and community structure of prokaryotes and nitrifiers, and nitrification rates in estuarine sediments from three distinct sites with specific chemical, physical and biological characteristics. The sampling area was the Sacca di Goro Lagoon of the Po estuary 13 (Italy). Microcosm stable isotope probing (SIP) experiments with CO2-labelling are carried out to identify dominating populations of ammonia oxidisers, and to clarify whether the contribution of AOA and AOB to gross nitrification is a function of their abundance and of pH in sediments. First results suggest that AOA clearly dominate the system even under high loads of ammonium and at high pH. This research project significantly advances our understanding of the role of Archaea in the nitrogen cycle in coastal transition systems subject to high inputs of nitrogen and under strong anthropogenic pressure.

191 TUESDAY 10 SEPTEMBER 2013, 17:30 PS-2. Bacterial diversity: from community composition to community functions

PS-2.38. PROKARYOTIC COMMUNITIES INHABITING THE ANTARCTIC LAKE LIMNOPOLAR (LIVINGSTON ISLAND, SOUTH SHETLAND ISLANDS)

Maria Papale, University of Messina (Italy) Coauthors: Lo Giudice A, Conte A, Camacho A, Michaud L

The lake Limnopolar (Livingston Island, South Shetland Islands, Antarctica) is a small monomictic cold lake with a single water circulation in summer and a thermal stratification during the rest of the year. The present work was aimed at analyzing the prokaryotic community inhabiting the lake surface waters. A polyphasic approach, which included culture-dependent and -independent techniques, was applied. The metabolically active fraction of the community was analyzed by sequencing cDNA clone libraries. The predominance of the Alpha- (34%; mainly affiliated to the genus Sphingomonas) and Betaproteobacteria (31%; mainly affiliated to the genus Polaromonas), followed by the Bacteroidetes (14%; mainly affiliated to the genus Flavobacterium) and Actinobacteria (8%) was observed. The Catalyzed Reporter Deposition Fluorescence in Situ Hybridization (CARD-FISH) revealed that a significant fraction of cells were hybridized with the bacterial probe EUB (88%). Among them, the Betaproteobacteria and Bacteroidetes represented the 58 and 15%, respectively. Cells hybridized with the probe ARCH915 accounted for the 1.2% of total cells, and were mainly represented by the Crenarchaeota (probe CREN537). The 323 strains that were isolated from agar plates were predominantly representative of the Actinobacteria (45%) and Gammaproteobacteria (40%; typically of marine origin), followed by the Firmicutes (10%; often reported in association with microbial mats) and Bacteroidetes (5%). In particular, Arthrobacter members, which were mainly strongly related to A. livingstonensis strain L12, predominated among the Actinobacteria. The Gammaproteobacteria were predominantly represented by the genera Pseudomonas and Psychrobacter. Among the Bacteroidetes, members of the genera Chryseobacterium and Flavobacterium were present. Finally, the Firmicutes were mainly represented by affiliates to the species Sporosarcina psychrophila. The occurrence of genera that are atypical for surface water of a freshwater lake was observed. This finding suggests that the composition of bacterial community may include bacteria that are generally associated with sediments or microbial mats. Moreover, results highlight the presence of halophilic or halotollerant bacteria that probably come to the lake via marine aerosols.

192 TUESDAY 10 SEPTEMBER 2013, 17:30 PS-2. Bacterial diversity: from community composition to community functions

PS-2.39. ASSESSING THE OYSTER MICROBIOME: DIFFERENCES IN FUNCTIONAL AND SPECIES DIVERSITY

Melissa Pierce, University of Connecticut, Dept. of Marine Sciences (USA) Coauthors: Holohan BA, Ward JE, Zhao X, Hicks RE

Bacteriological studies of various species of oysters have been carried out since the 1950’s, but have largely focused on indicator organisms and known pathogens. Broad based ecological studies have only become possible with the recent evolution of molecular techniques. However, many studies still homogenize whole organisms and do not evaluate tissue specific bacterial communities. This study assessed spatial and temporal differences of the gut and pallial fluid microbiomes of the eastern oyster (Crassostrea virginica) from three sites within Long Island Sound, USA over a one year period. A number of culture-dependent and independent methods were employed to obtain a broad view of the microbial communities present, ranging from species specific (Terminal Restriction Fragment Length Polymorphism; fluorescence in situ hybridization) to more general metabolic community profiling (Biolog EcoPlatesTM). The relationships between level of pathogen infection (Dermo disease; Vibrio spp.), whole-animal condition, and microbial communities were also assessed. Major findings show that functional diversity, or metabolism, is a more commonly shared feature than bacterial species. This theme of metabolic redundancy was recurrent, especially between communities of the oyster gut. Microbiome species diversity was highly variable between oysters even from the same site, suggesting that extrinsic and intrinsic factors influence community structure. Data from this study will be used to inform future work on pathogen colonization of the oyster gut and the potential of to act as vectors for disease.

193 TUESDAY 10 SEPTEMBER 2013, 17:30 PS-2. Bacterial diversity: from community composition to community functions

PS-2.40. AQUACULTURE BIOLOGICAL FILTERS: EFFECT OF OZONE TREATMENT ON THE MICROBIAL COMMUNITY

Alessandro Ciro Rappazzo, University of Messina (Italy) Coauthors: Interdonato F, Lo Giudice A, Zoppini A, Amalfitano S, Casella P, Blancheton JP, Michaud L

The key biological filtration processes involved in Recirculating Aquaculture Systems (RAS) need to be better understood, especially those determining the development of the bacterial populations and their interactions with fish. In particular, the RAS technology require a knowledge-based approach, focusing more on the system as a microbial management strategy for improving and stabilizing both physiochemical and microbial water quality. The aim of present research was to study the effect of the ozone treatment (used as general disinfectant) on the biofilter communities, abundances (via flow cytometry), diversity (via 16S rDNA clone libraries) and activity (via Ectoenzymatic activities: beta-glucosidase, alkaline phosphatase and lipase aminopeptidase). One system was set up as control (natural) and a second was set up with an increased Red-Ox level, by a continuous addiction of ozone (ozonated). Results showed a reduction of bacterial abundance in the ozonated system (2.03x108 ± 1.02 x107 cells/ml) compared to the natural one (1.59x108 ± 7.93x106 cells/ml). Generally, the microbial community seemed to be more efficient in the utilization of proteinaceous and lipidic compounds. The alkaline phosphatase and β-D-1, 4 glucosidase activities were higher in natural biofilters than in ozonated ones. A total of 116 and 138 clones were sequenced and 40 and 43 phylotypes were identified in the ozonated and in the natural system, respectively. Alphaproteobacteria (36.21%) were most abundant, followed by Gammaproteobacteria (26.72 %) and Flavobacteria (15.52 %) in the ozonated system. In the natural system previous percentages resulted in 32.61, 23.19 and 22.46 %, respectively. In conclusion, ozonation (within certain limits, not affecting the fish welfare) seemed to have only a moderate impact on the microbial community colonizing biological filters, and the biofilter nitrification efficiency was only slightly reduced by this treatment.

194 TUESDAY 10 SEPTEMBER 2013, 17:30 PS-2. Bacterial diversity: from community composition to community functions

PS-2.41. PLANKTONIC BIODIVERSITY GRADIENTS AND ECOSYSTEM FUNCTIONS IN SCANDINAVIAN LAKES

Serena Rasconi, WasserCluster Lunz (Austria) Coauthors: Striebel M, Andersen T

The role of biodiversity is important for ecosystem functions as productivity, adaptability to change and resistance to biological invasions, and for providing and sustaining ecosystem services as well. Lakes are ideal systems for testing predictions and responses related to biodiversity since they are units with well-defined boundaries, as inverted islands isolated by land. A strong east- west gradient in both phytoplankton and zooplankton species richness makes a longitudinal transect across Norway and Sweden a natural laboratory for investigating effects of biodiversity on natural functioning. We approached the relationships between species pool saturation and ecosystem functioning by two combined approaches: field sampling of natural biodiversity gradients (COMSAT project), and controlled mesocosms experiments (BioGrad project). Microbial eukaryotes diversity has been analyzed by molecular methods (Sequencing and T-RLFP) and up- scaling by predictive modeling tools. During the COMSAT project 76 lakes were sampled across the previously detected diversity and productivity gradient. Results from this environmental survey support the expected longitudinal pattern and a corresponding change in evenness from west to east. Also a noticeable result was the ubiquity of the phylum Cryptophyta in all samples. During the BioGrad experiment (conducted in the mesocosms facility of Umeå, Sweden) natural communities from two lakes located one in W-Norway (Storvatnet) and one in E- Sweden (Väster-Rännöbodsjön), with similar local productivity (total phosphorus) and different species richness, were exposed to a threefold productivity gradient (gradient in nutrient addition) under highly controlled conditions. Clone libraries were constructed for the T zero and at the end of the experiment (T final, 4 weeks later). Molecular analysis results confirmed the expected longitudinal diversity gradient, so that higher number of OTUs was found in Sweden (50) than in Norway (39). At the end of the experiment the diversity decreased in the higher nutrients treatments and interesting in Storvatnet (Norway) only photosynthetic organisms in the class of Cryptophyta and Chlorophyta were retrieved. In Väster-Rännöbodsjön (Sweden) the diversity in the high nutrients treatments was greater than in Norway and different functional groups were represented by autotrophs and heterotrophs. The results showed an effect of the initial community composition along the treatments, with the more diversified community performing better when exposed to higher productivity.

195 TUESDAY 10 SEPTEMBER 2013, 17:30 PS-2. Bacterial diversity: from community composition to community functions

PS-2.42. DISTRIBUTION OF MICROBIAL COMMUNITIES IN THE WATER COLUMN, ANOXIC SEDIMENT, AND MICROBIAL MATS OF MEROMICTIC LAKE CADAGNO BY PYROSEQUENCING ANALYSIS

Damiana Ravasi, Laboratory of Applied Microbiology, Bellinzona (Switzerland) Coauthors: Peduzzi R, Tonolla M

Lake Cadagno, in the southern range of the Swiss Alps, is one of the last natural meromictic lakes remaining in Europe. Its waters are permanently stratified with an oxygenated freshwater layer (mixolimnion) overlaying a saline, anoxic water column (monimolimnion). At the interface between the two layers (chemocline), communities of anaerobic phototrophic bacteria find the ideal conditions for their development. Moreover, a variety of microbial mats grows in patches in proximity of the sublacustrine sulphurous springs in the southern lake’s littoral. The diversity of bacterial communities in Lake Cadagno has been studied for decades, focusing on specific key communities, such as anaerobic phototrophic bacteria (Chromatiaceae, Chlorobiaceae) in the chemocline and sulfate-reducing bacteria in the monimolimnion and anoxic sediment. In order to obtain a broader assessment of the lake’s biological communities, we analysed samples from several depths of the lake’s mixolimnion, monimolimnion, and chemocline, from the anoxic sediment, and from twelve different microbial mats. Genomic DNA was extracted and high- throughput tag-pyrosequencing was applied to the V1-V3 16S rRNA gene region. The data set comprised 92, 742 high-quality sequences with an average sequence length of 398 bp. The total number of OTUs at 97% sequence similarity ranged from 62 to 153. Among the different diversity indices calculated, the Good’s coverage index was higher than 97% in all type of habitat analysed, indicating that their diversity was well covered and confirming the usefulness of pyrosequencing to gain a rapid overview of the diversity in bacterial communities thriving in the lake. The composition of bacterial communities among the habitat types investigated showed already a great variability at the taxonomic level of phylum. Communities in the three water strata differed from each other, from the sediments, and from the microbial mats. Anoxygenic photosynthesizers dominated the chemocline, as previously found, and the monimolimnion. The anoxic sediment was largely dominated by a Firmicute, Geobacillus sp., in disagreement with previous studies and indicating potential for sampling biases. Microbial mats communities were composed of the same main phyla, with oxygenic and anoxygenic photosynthesizers dominating the bacterial communities.

196 TUESDAY 10 SEPTEMBER 2013, 17:30 PS-2. Bacterial diversity: from community composition to community functions

PS-2.43. DEGRADATION OF TERRESTRIAL ORGANIC CARBON (TOC): ARE PARTICLE ASSOCIATED BACTERIA IMPORTANT

Angelika Rieck, Institute for Freshwater Ecology and Inland Fisheries (IGB), Stechlin (Germany) Coauthors: Herlemann D, Manecki M, Jürgens K, Dittmar T, Grossart HP

The large pool of terrestrial organic carbon (tOC) stored in permafrost soils of the northern hemisphere is increasingly mobilized by melting of permafrost soils and thus enters marine habitats, especially during the spring flood (May-June). However, only little is known about mechanisms of microbial tOC degradation in marine habitats. Different have different abilities to degrade organic matter by exoenzymes. In particular, microorganisms attached to particles are known to express high exoenzymatic activities resulting in a rapid degradation of tOC with far-reaching consequences for the global carbon cycle. We hypothesize that particle associated microorganisms, in particular fungi, will benefit from the increased input of tOC and thereby play an important ecological role in aquatic foods webs. To test for the role of tOC in aquatic food webs at different salinities, long-term incubation experiments were established in summer and winter using Baltic Sea water with 3 salinities (marine 32 PSU, brackish 7 PSU & limnic 2 PSU) as inoculum. The Baltic Sea represents a suitable model system to study the degradation of tOC under different environmental conditions since it provides an extended salinity gradient from marine to almost limnic conditions and has long retention times varying between 3 to 30 years. Thereby, sterile Kalix River water (North Sweden) served as a tOC source. Effects of particle associated bacteria and fungi on tOC degradation was analyzed by comparing microbial data (epifluorescence microscopy and 454 pyro-sequencing) with organic matter finger prints (ultra high definition mass spectrometry; FT-ICR-MS). First results of the winter experiment reveal differences between free-living and particle associated microbial abundance and community composition along the salinity gradient as well as a shift over time. Our preliminary data suggest that tOC particles provide an important habitat for bacteria as well as fungi where specific microbial communities can increase the metabolic capabilities for tOC degradation in the ocean.

197 TUESDAY 10 SEPTEMBER 2013, 17:30 PS-2. Bacterial diversity: from community composition to community functions

PS-2.44. PHOSPHATE AND ATP DYNAMICS IN MOUNTAIN LAKES: ROLE OF DISTINCT FRESHWATER BACTERIAL GROUPS IN PHOSPHORUS CYCLING

Carina Rofner, University of Innsbruck, Institute of Ecology (Austria) Coauthors: Perez MT, Sommaruga R

We assessed the inorganic and organic phosphorus dynamics in two mountain lakes differing in their trophic status: Gossenköllesee (GKS) an oligothropic high-mountain lake (2417 m a.s.l.) and Piburgersee (PIB) a meso-oligotrophic subalpine lake (913 m a.s.l.). Seasonal changes in inorganic and organic phosphorus (ATP) concentrations were assayed with radiotracers and chemically after magnesium-induced-coprecipitation (MAGIC). Additionally to bulk incorporation rates of both phosphate and ATP by the entire microbial community, incorporation of these substrates by individual bacterial groups was studied combining two single-cell techniques: micro- autoradiography and fluorescent in situ hybridization with catalysed reporter deposition (MAR- CARD-FISH). The assayed concentrations of bioavailable phosphate (GKS 4.68 nM±1.7; PIB 7.07 nM±1.74) and ATP (GKS 1.5 nM±0.06; PIB 4.25 nM±2.37) were typical for phosphorus depleted systems. In autumn and spring, phosphorus turnover times were short in both lakes averaging 20- 30 min for phosphate and 30-60 min for ATP. In January, turnover time increased to 5-40 h. In GKS, β-Proteobacteria was the most active bacterial group in phosphate uptake, whereas Actinobacteria was more active in ATP incorporation. α-Proteobacteria and Cytophaga seemed to take up both substrates at similar rates. In PIB, α-Proteobacteria and Cytophaga dominated phosphate uptake in the epilimnon, whereas β-Proteobacteria appeared active in both the epi- and hypolimnon. This multi-approach shows that bacterial communities in mountain lakes are particularly phosphorus-starved and suggests rapid but competitive uptake of phosphate and ATP.

198 TUESDAY 10 SEPTEMBER 2013, 17:30 PS-2. Bacterial diversity: from community composition to community functions

PS-2.45. EFFECTS OF COURSE DISRUPTION BY DAMS ON RIVERINE BACTERIOPLANKTON COMMUNITY STRUCTURE

Clara Ruiz-González, Université du Québec à Montréal (Canada) Coauthors: Proia L, Salazar G, Logares R, Gasol JM, Sabater S

Large rivers are commonly regulated by damming, yet the impact of such disruption on prokaryotic communities has seldom been studied. Here we describe the effects of a large reservoir system located in the Ebro River (NE Spain) on the spatio-temporal patterns of bacterioplankton community structure by comparing several sites located above and below the impoundments, which were sampled on three occasions. Microscopic assessment of bacterial composition by means of rRNA gene probing revealed that communities differed significantly between upstream and downstream sites. Compared to upstream sites, downstream locations presented a pronounced decline in groups like β-proteobacteria, γ-proteobacteria and Bacteroidetes, as well as in the number of particle-attached and filamentous prokaryotes, whereas small-sized free-living α-proteobacteria and Actinobacteria significantly increased after the reservoirs. Redundancy analysis revealed that conductivity, temperature and nitrate were the environmental predictors that best explained the observed variability among bacterial assemblages. Subsequent 454 pyrosequencing of the 16S rDNA gene allowed us to explore the intra-group composition of the dominant broad phylotypes detected by probe hybridization, which were shown to be differentially affected by the presence of the reservoirs, not only in terms of their relative contribution to community composition, but also regarding to their richness, taxonomic diversity and degree of phylogenetic similarity (i.e. co-occurring bacteria more phylogenetically related to each other than expected by chance). Altogether, our results indicate that the environmental change produced by the impoundment promoted the structuring of different bacterioplankton communities in upstream and downstream sites. Such modifications in community structure may have implications for ecosystem functioning and local biogeochemical processes.

199 TUESDAY 10 SEPTEMBER 2013, 17:30 PS-2. Bacterial diversity: from community composition to community functions

PS-2.46. LINKS BETWEEN DOM COMPOSITION AND FUNCTIONAL CAPACITIES OF BACTERIOPLANKTON COMMUNITIES ACROSS TEMPERATE AND BOREAL LAKES AND RIVERS

Clara Ruiz-González, Université du Québec à Montréal (Canada) Coauthors: Lapierre JF, Nino JP, del Giorgio P

The Biolog ® EcoPlates have been extensively used as a proxy of the functional capacities of natural bacterial communities across diverse soil and aquatic ecosystems. The resulting substrate utilization profiles have often been assumed to reflect some aspect of the taxonomic structure of the bacterial assemblages, yet very little is known about the role that the composition of the in situ dissolved organic matter (DOM) plays in determining this catabolic potential of bacterial communities. Here we explore the large-scale patterns of Biolog substrate utilization profiles and of the fluorescence properties of DOM across 260 temperate and boreal lakes and rivers from several regions in Northern Québec, as well as the links between the two. The large differences in physico-chemical and biological conditions observed among the sampled regions were not reflected in clear regional segregation of the functional response of bacterial communities. However, consistent differences in Biolog profiles were observed between rivers and lakes when regions were considered either together or separately, a pattern that coincided with differences between lakes and rivers in the relative abundances of the major humic, fulvic, and protein-like fluorescent components of DOM. Our results point to a major influence of the quality of the in situ available carbon pool in determining the catabolic profile of bacterial assemblages. Further research is needed to ascertain the relative importance of both DOM and bacterial composition as drivers of functional diversity as quantified by Biolog EcoPlates.

200 TUESDAY 10 SEPTEMBER 2013, 17:30 PS-2. Bacterial diversity: from community composition to community functions

PS-2.47. FUNCTIONAL DIVERSITY OF BACTERIOPLANKTON IN THE WORLD’S OCEANS

Maria Montserrat Sala, Institut de Ciències del Mar (CSIC), Barcelona (Spain) Coauthors: Borrull E, Antequera C, Azúa I, Bana Z, García-Zarandona I, Ayo B

During the circumnavigation expedition Malaspina we took samples in the Atlantic, Indian and Pacific oceans in order to assess functional diversity of bacterioplankton in vertical profiles from surface to 4000 m. We tested the utilization of 95 carbon sources (i.e. carbohydrates, amino acids, carboxylic acids) included in the Biolog GN plates, and 8 additional sources selected by their relevance in marine environments. Samples were inoculated in the microplates, incubated in the dark at in situ temperature and the absorbance of the plates was measured at 590 nm. The results show a generally higher utilization of carbohydrates and amino acids in the upper layers (above 100m) of all the oceans, , with the highest results in the Pacific Ocean. The utilization of carbon sources in the deep ocean was lower, with the exception of an area in the southern Pacific Ocean where utilization of carbohydrates, amino acids and carboxylic acids, at 4000 m exceeded even that found in the upper layers of the oceans.

201 TUESDAY 10 SEPTEMBER 2013, 17:30 PS-2. Bacterial diversity: from community composition to community functions

PS-2.48. METAGENOMIC ANALYSIS OF THE SUBOXIC LAYER IN HUMIC LAKES

Lucas Sinclair, Evolutionary Biology Centre, Uppsala (Sweden) Coauthors: Peura S, Bertilsson S, Eiler A

Humic lakes play an important role in the ecosystem functioning and element cycling of the boreal landscape. The diversity and functional potential of the principal actors of these environments – microbes – is just beginning to be unraveled with the help of new technologies. This study reports on a pyrosequencing metagenomic analysis of three such meromictic lakes including samples from the epi-, meta- and hypolimnion. These humic lake samples were compared to those of 12 temperate freshwater lakes representing oligotrophic to eutrophic systems. A median of 190'000 reads were obtained per sample after quality cleaning, from which a total of more than 3000 16S marker gene fragments were retrieved to estimate the phylogenetic diversity. Functional diversity was explored using predicted proteins on unassembled reads. Results from the phylogenetic analysis reveal that humic systems were distinct amongst lakes. For example, high amounts of candidate divisions OD1 and OP11 found in the suboxic layer of the humic lake samples were sparsely detected in the other systems. Preliminary analyses on the functional composition show changes along trophic gradients in the typical freshwaters with the humic lakes forming a distinct out-group. Results are pending to discuss the differences in carbon processing discriminating humic lakes from other aquatic systems, and moreover, intrinsic differences of such humic systems across their stratified layers. We hypothesize that anaerobic processes are dominating in the hypolimnia. In particular, we will investigate the presence of genes involved in methane oxidation and autotrophic denitrification that have been supposed to occur in boreal stratified lakes based on stable isotope and taxonomic data.

202 TUESDAY 10 SEPTEMBER 2013, 17:30 PS-2. Bacterial diversity: from community composition to community functions

PS-2.49. INFLUENCE OF FISH COMMUNITY STRUCTURE AND TROPHIC CASCADES ON THE BACTERIOPLANKTON COMMUNITY IN AN EXPERIMENTALLY MANIPULATED SYSTEM

Caroline Souffreau, Laboratory of Aquatic Ecology, KU Leuven (Belgium) Coauthors: Lemmens P, De Meester L

Several studies have shown that the bacterioplankton community composition is mainly determined by the local environmental conditions, including both biotic and abiotic factors, an ecological process called species sorting. However, the biotic factors are often overlooked and their importance for the bacterioplankton community structure less known. It remains therefore unclear how strong freshwater bacterioplankton communities are affected by changes in higher trophic levels through trophic cascades. In this field experiment, we aimed to get further insight into the local environmental factors (abiotic and biotic) determining the community structure of freshwater bacterioplankton, and investigated whether trophic cascades starting at the fish level cascade down to the bacterioplankton community level. We manipulated the fish stocks of 24 fish ponds, resulting in four fish treatments (dominance by (i) planktivorous fish, (ii) benthivorous fish, (iii) planktivorous and benthivorousfish, (iv) planktivorous, benthivorous fish and Pike) and added a refugium for predator birds in half the treatments in a full factorial design. One year later, samples were taken for abiotic parameters (DOC, pH, nutrient levels, among others), and community structure of zooplankton, phytoplankton and bacterioplankton. The bacterioplankton community composition was determined by 454-pyrosequening. We determined the influence of fish and zooplankton biomass and the remaining local environmental variables in explaining the variation in bacterioplankton community composition (BCC). The four fish treatments and two refugium treatments had no significant effect on the BCC, but fish and zooplankton biomass did. However, variation partitioning showed that the fish and zooplankton biomass on themselves did not explain a significant portion of the variation in BCC, whereas the remaining environmental variables did (29.5%). Our results thus show that fish biomass has only an indirect effect on the BCC through changes in the remaining environmental variables, indicating an indirect .

203 TUESDAY 10 SEPTEMBER 2013, 17:30 PS-2. Bacterial diversity: from community composition to community functions

PS-2.50. AQUACULTURE PATHOGENIC VIBRIOS: ANTIBACTERIAL ACTIVITY TOWARDS THEM BY SOME MARINE MACROALGAE

Loredana Stabili, University of Salento, DiSTeBA, Lecce (Italy) Coauthors: Acquaviva MI, Cecere E, Narracci M, Petrocelli A, Cavallo RA

In aquaculture diseases of microbial origin can cause significant economic losses worldwide and vibriosis, caused by bacteria of the genus Vibrio, can produce high fish and shellfish mortality. Moreover, the development of Vibrio resistance to antibiotics has caused a growing need for the search of new antibacterials effective in veterinary medicine and characterized by limited undesirable side effects. In recent years seaweeds increasingly attracted interest as promising source for metabolites with antimicrobial activity. The aim of this study was to identify seaweeds with antibacterial activity against some pathogenic Vibrio, in order to create a possible alternative to the commonly used antibiotics in aquaculture. Chloroform/methanol lipidic extracts of five seaweed species (Chaetomorpha linum, Cladophora rupestris, Gracilaria dura, Gracilariopsis longissima, Undaria pinnatifida) were tested for their antibacterial activities against fish and shellfish pathogenic vibrios using a disc diffusion method. Different susceptibilities to lipidic algal extracts resulted. Gracilariopsis longissima lipidic extract showed the highest activity against Vibrio ordalii, Vibrio salmonicida, Vibrio alginolyticus and Vibrio vulnificus. The extracts of all the examined seaweeds were able to inhibit the growth of Vibrio ordalii. The obtained results indicate that the here studied seaweeds represent interesting potential biotechnological resources suggesting their use as a source of antibacterial compounds as well as a health-promoting feed for aquaculture.

204 TUESDAY 10 SEPTEMBER 2013, 17:30 PS-2. Bacterial diversity: from community composition to community functions

PS-2.51. JELLYFISH AND THE BACTERIAL COMMUNITY OF VARANO LAKE

Loredana Stabili, University of Salento, DiSTeBA, Lecce (Italy) Coauthors: Caprioli R, Kos Kramar M, Scorrano S, Boero F, Turk V, Piraino S

Swarms or blooms of different jellyfish species may influence the bacterial community composition as well as the water quality, especially in the enclosed areas where jellyfish are present all year round. Varano lake (Italy) is a shallow, enclosed lagoon, very touristic and for ten years has been constantly inhabited with dense population of jellyfish Aurelia sp. In this lagoon seawater samples for microbiological analyses were collected in two different areas (P and M, according to the presence or absence of jellyfish respectively) within the European Seventh Framework Programme project VECTORS (Vectors of Change in Oceans and Seas , Impact on Economic Sectors). Different classical cultural methods were performed to determine the number of the heterotrophic bacteria, total culturable bacteria at 37°C, vibrios, intestinal enterococci, total and fecal coliforms. In addition the identification of culturable heterotrophic isolates was made by using 16S rRNA gene sequence analysis. The highest density of heterotrophic bacteria and vibrios has been recorded in the seawater collected nearby the jellyfish.. The highest concentrations of microbial pollution indicators and total bacteria culturable at 37°C has been observed in the area where jellyfish were absent. Comparative sequence analysis of culturable heterotrophic isolates showed that the main bacterial community of the Varano lake was represented by the culturable species of γ-Proteobacteria. Further studies are needed to confirm the preliminary results and to compare any changes with different Mediterranean areas where jellyfish blooms occur.

205 TUESDAY 10 SEPTEMBER 2013, 17:30 PS-2. Bacterial diversity: from community composition to community functions

PS-2.52. FIRST INSIGHT VIBRIOS DIVERSITY IN THE MUCUS OF THE POLYCHAETE MYXICOLA INFUNDIBULUM (ANNELLIDA, POLICHAETA)

Loredana Stabili, University of Salento, DiSTeBA, Lecce (Italy) Coauthors: Giangrande A, Pizzolante G, Caruso G, Alifano P

Vibrios are highly abundant in aquatic environments, where they actively participate in the re- cycling of nutrients and detritus. In addition they are a highly diverse group containing both free- living and associated species living as mutualists, saprophytes or as parasites with several marine organisms. In this study we have analyzed vibrios abundance and diversity in the mucus of the polychaete Myxicola infundibulum complementing culture-based with molecular methods. Vibrios represented a conspicuous component of the heterotrophic culturable bacteria and their concentration was 4.5×103 CFU ml-1. Luminous vibrios accounted about 60% of the total culturable vibrios. The isolates were assigned to: Vibrio gigantis, V. fischeri, V. jasicida, V. crassostreae, V. kanaloae and V. xuii. Two Vibrio isolates (MI-13 and MI-15 ) may belong to a new species. The association of the isolated vibrios with M. infundibulum mucus could be explained with their feeding activity of the Vibrio species on the mucus. Its broad spectrum of hydrolytic enzymes is, indeed, an indirect indication of its role in mucus digestion and transformation. We can conclude that the mucus could represent a microcosm and a food source for some Vibrio species playing a crucial role in the structuring of a beneficial mucus-associated microbial community. The trophic relationship between vibrios and M. infundibulum mucus could be also enhanced by the protection that mucus offers to vibrios as already observed for other polychaetes. This work represents a contribute to the growing evidence for complex and dynamic invertebrate-microbe associations present in nature. Moreover, exploring vibrios isolated from the mucus of M. infundubulum could be an attractive task since they possibly host a great potential for diverse applications including biotechnologies.

206 TUESDAY 10 SEPTEMBER 2013, 17:30 PS-2. Bacterial diversity: from community composition to community functions

PS-2.53. DIVERSITY OF THE BACTERIAL COMMUNITY ASSOCIATED WITH THE NON-INDIGENOUS SEAWEED CAULERPA RACEMOSA (CHLOROPHYTA, CAULERPACEAE)

Loredana Stabili, University of Salento, DiSTeBA, Lecce (Italy) Coauthors: Rizzo L, Tredici SM, Pizzolante G, Fraschetti S, Alifano P

Marine macroalgae play a key role in the productivity of coastal ecosystems releasing dissolved organic carbon. Their surface is usually colonized by eukaryotic and prokaryotic microorganisms. In this association, algae may gain vital elements from the colonizing bacteria, which, in turn, protect their hosts from micro- and macrofouling by the production of bioactive compounds, thus displaying a potential relevant functional role. Introductions of non-indigenous species together with their organism-associated bacteria are little studied, although are probably more frequent than supposed. Here, we studied the diversity of the bacterial community associated with Caulerpa racemosa. This non-indigenous species, introduced from the Red Sea, is widely distributed in the Mediterranean Sea colonising both hard and soft substrata across habitats leading to deep alterations of indigenous assemblages. Caulerpa racemosa was collected at Torre Guaceto (Brindisi, Italy). The heterotrophic bacteria and vibrios on its surface were isolated in Marine Agar and thiosulphate/citrate/bile salts/sucrose agar and then their abundances were quantified. In addition, phenotypic characterization of the isolates was performed by several morphological cultural tests. Molecular analysis was performed senquencing partial 16S rDNA amplicons obtained by polymerase chain reaction (PCR) using 16S rRNA genespecific “universal” primers. The results of microbiological cultural analysis documented that culturable heterotrophic bacteria accounted for 3.2 x 104 CFU/ml and vibrios represented about 4 % of the total C. racemosa surface cultivable bacteria. 16S rRNA gene analysis identified the following genera on C. racemosa surface: Vibrio, Bacillus, Shewanella, Marinobacter, Arthrobacter. The recovery of some strains suggests that this algal species harbors a specific microbial community. Further studies are needed to clarify the nature of the observed association, since it might contribute to explain the ecology of this invasive seaweed.

207 TUESDAY 10 SEPTEMBER 2013, 17:30 PS-2. Bacterial diversity: from community composition to community functions

PS-2.54. ALUMINUM AND COPPER SHAPE THE FUNCTIONS OF MICROBIAL COMMUNITY IN SINGAPORE URBAN CATCHMENT

Sanjay Swarup, Department of Biological Sciences, National University of Singapore Coauthors: Saxena G, Khanal K, Reuben S, Kalyan CM, Nyi Nyi N, Liang Y, Piceno Y, Zhou J, Kjelleberg S, Mantha P, Rajal V, Andersen GL

Rapidly increasing urban populations have led to increase of pollutant levels with different land use types in the urban catchments. This increase is associated with specialization of microbial communities and possible shifts in the geochemical cycling. Microbial communities play a critical role in the geochemical processes, which makes it important to identify key environmental parameters that influence the community structure and its function in this context. With the aim to study the influence of land use type and environmental parameters on the structure and function of microbial communities, the present study was conducted in an urban catchment, where the metal and pollutants levels are under allowable limits. Sediment and water samples were collected after the rain event from storm water canal in a 25 km2 catchment of Singapore and examined for functional genes (GeoChip2.0), microbial species (Phylochip) and 38 environmental variables including 7 physical traits, 5 ions, 12 metals and 3 antibiotics and 11 organics. Sediments were found more diverse in taxa than overflowing water. Dominant phyla, for example, Firmicutes and Bacteroidetes were found to be significantly higher in water, while less dominant ones such as, Chloroflexi, Planctomycetes and Verrucomicrobia were higher (p<0.05) in sediments, indicating that the less abundant phyla take refuge in sediments. But, the functions of the same microbial community were different in the two land use types. Abundance of 328 gene variants was significantly different (p<0.05; unpaired t-test, Bonferroni correction) between the microbiomes of residential and industrial land use types. Selected gene abundance levels were validated using quantitative-polymerase chain reaction (Q-pcr). Whereas, genes involved in arsenic tolerance were more abundant in industrial areas, copper tolerant genes were higher in residential areas. Aluminum and copper significantly explained 15% and 14% of variation in the functional gene abundance. About 25% of total variation was explained with both metals taken together. This study will also include results from further investigation on the impact of Al on Pseudomonas stains isolated from environmental sediments samples. From this study, we conclude that from a large number of environmental parameters, a selected few can be significantly affect the functioning of the microbial community and in this unbar environment, these environmental parameters are aluminum and copper.

208 TUESDAY 10 SEPTEMBER 2013, 17:30 PS-2. Bacterial diversity: from community composition to community functions

PS-2.55. EFFECT OF SOLAR RADIATION, GRAZING AND RESOURCE AVAILABILITY ON HETEROTROPHIC BACTERIA IN SURFACE WATERS OF THE WORLD OCEANS

Teira E, Universidade de Vigo (Spain) Coauthors: Hernando-Morales V, Hernández M, Morán XAG, Ferrera I, Varela MM, Gasol JM

The response of bacteria to solar radiation may depend on several factors including the intensity of radiation, the ability to adapt to different light regimes (physiological or community composition changes) or also the degree of nutrient limitation/starvation. In order to provide a better understanding of the role of solar radiation, as well as the relative importance of top-down and bottom-up control processes in bacterial production, growth and diversity (assessed with the ARISA fingerprinting technique) in surface waters of the world oceans, we conducted a series of 11 microcosm experiments from December 2010 to June 2011 at stations located between 30 ºN and 30ºS, including the Atlantic, Pacific and Indian oceans. Each experiment consisted of 4 treatments, including a control (unfiltered water), a filtered treatment (0.8 mm filtered seawater), a light diluted treatment (0.8 mm filtered water 20% diluted with 0.2 mm water) and a dark diluted treatment (0.8 mm filtered water 20% diluted with 0.2mm water kept under dark conditions) which were incubated in UVR transparent carboys under natural light cycles during 4 days. The effect of solar radiation on bacterial production rates was overall negative, causing reductions in bacterial production ranging from 10 to 50%. The upper mixed layer depth and the daily DNA damage UV dose explained ca. 60% of the variability in the magnitude of BP inhibition. The higher was the mixed layer depth, the higher the inhibition. For a similar mixed layer depth, the negative effect was higher when UV radiation was higher. The reduction of grazing pressure in the filtered treatment had a clear positive effect on BP only in 3 out of 11 experiments. The magnitude of BP increase after predator removal was positively correlated with the initial bacterial abundance. The increase of resource availability by dilution promoted bacterial growth and an increase in the relative abundance and cell size of HNA-bacteria. The manipulation of nutrient availability, grazing pressure and light caused changes in bacterial community composition, although the resulting community composition was mostly determined by the initial bacterial assemblage.

209 TUESDAY 10 SEPTEMBER 2013, 17:30 PS-2. Bacterial diversity: from community composition to community functions

PS-2.56. ANNUAL SHIFTS IN THE STRUCTURE AND FUNCTION OF A COASTAL BACTERIAL COMMUNITY IN THE EASTERN CANTABRIAN SEA

Ainhoa Uranga, University of The Basque Country, Leioa (Spain) Coauthors: Abad N, Bana Z, Arrieta JM, Ayo B, Iriberri J

The relation between the bacterial community composition and activity in space and time is one of the central topics in microbial ecology. Diversity and function in microbial communities are usually related, thus variations microbial community structure are thought to play a major role in regulating the biogeochemical processes mediated by microbial communities. The aim of this work was to establish links between the composition of the bacterial community and their function at a costal station in the Eastern Cantabrian Sea. We followed the composition of the bacterial community from February 2011 until December 2012, together with some relevant parameters such as bacterial abundance, production and respiration. Two contrasting situations characterized by high and low levels of bacterial production were detected: a high productivity (HP) situation from May to August and a low productivity (LP) situation from October until March, respectively. These situations were separated by brief periods of change, characterized by intermediate values of production that we will call transition (T) periods.

210 TUESDAY 10 SEPTEMBER 2013, 17:30 PS-2. Bacterial diversity: from community composition to community functions

PS-2.57. LIPID BIOMARKERS AND GENE EXPRESSION: INSIGHTS ON KEY PLAYERS OF THE NITROGEN CYCLE

Laura Villanueva, Royal Netherlands Institute for Sea Research Den Burg (Netherlands) Coauthors: Lipsewers Y, Bale N, Hopmans EC, Schouten S, Sinninghe Damsté JS

Several lipid biomarkers are excellent proxies for the presence of specific microbial groups and their biochemical processes but they cannot provide an accurate phylogenetic composition of the lipid producers. In contrast, genetic methods identify the taxonomical classification of the microbial community and the gene expression as a measure of activity but are prone to PCR biases, which are not an issue for lipid-based methods. Here, we will overview two different studies in which we have targeted the abundance, diversity, activity and possible interaction of two key microbial groups of the nitrogen cycle: anammox bacteria and ammonia-oxidizing Archaea (AOA, Thaumarchaeota). Both groups of microbes produce specific biomarker lipids, i.e. AOA produce crenarchaeol while anammox bacteria produce ladderane lipids. We analyzed crenarchaeol in of the intact polar lipid (IPL; markers for living organisms) form and in the core lipid (dead organisms) form in the water column and sediments of the North Sea and Lake Challa (Tanzania). In the North Sea, Thaumarchaeota were more abundant and active in the surface water in the Winter while in the surface sediment seasonality was not marked in terms of abundance. The characterization of sediment cores in depth indicates that AOA were slightly more abundant in the Summer while they were more active in the Winter. In contrast, anammox bacteria were more abundant and active in the Summer which suggests that despite sharing the same niche in the sediment they might not compete metabolically due to seasonal activity differences. In addition, a high relative abundance of IPL-crenarchaeol and AOA activity were detected in sediment cores down to 12 cm depth, which indicates the presence of an active living population of Thaumarchaeota even in anoxic sediments. In the stratified Lake Challa, the predominance of the more labile form of IPL crenarchaeol (HPH-crenarchaeol) indicated the presence of an actively living community of Thaumarchaeota involved in nitrification. Archaeal 16S rRNA clone libraries revealed the presence of thaumarchaeotal groups 1.1a (Nitrosoarchaeum- like) and 1.1b (Nitrososphaera-like) at and above the oxycline. In the anoxic deep water, high abundance of an IPL with the acyclic glycerol dialkyl glycerol tetraether (GDGT-0) core structure was evident. The predominance of archaeal 16S rRNA sequences affiliated to the uncultured crenarchaeota groups 1.2 and miscellaneous crenarchaeotic group (MCG) points to GDGT-0 as a possible indicator for uncultured mesophilic crenarchaeota.

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TUESDAY 10 SEPTEMBER 2013, 17:30 PS-2. Bacterial diversity: from community composition to community functions

PS-2.58. VARIABILITY AND DYNAMICS OF MICROBIAL COMMUNITY STRUCTURES IN THE SEA SURFACE MICROLAYER

Shu Kuan Wong, Atmosphere and Ocean Research Institute, University of Tokyo (Japan) Coauthors: Suzuki S, Kaneko R, Cui Y, Hamasaki K

The sea surface microlayer (SML) is a thin surface film located at the interface between the sea surface and the atmosphere. The SML is found to be a distinct environment with higher concentrations of organic materials as well as higher bacterial abundance. Therefore, it is hypothesized that different bacterial community could inhabit in the SML and the bacterial activity and biogeochemical processes in the SML could be different from those in the UW. This study aims to characterize the bacterial community composition in the SML as to help to elucidate the possible community structure and the role of bacteria in the SML and underlying water (UW). In doing so, we first focused on testing the efficiency of samplers in collecting a large volume of water samples for molecular microbiological studies. The efficiency of three microlayer samplers, the polycarbonate membrane (PC), glass plate (GP) and drum sampler (DS) in collecting microbiological samples for molecular analysis were tested. Environmental and biological parameters such as salinity, wind speed, temperature as well as the concentration of transparent exopolymer (TEP), chl-a and bacterial abundance in both the SML and UW were also measured. Bacterial communities in the surface microlayer or bacterioneuston and the underlying water within Aburatsubo Inlet, Japan and its adjacent coastal water were compared using the polymerase chain reaction (PCR), denaturing gradient gel electrophoresis (DGGE) and 454 pyrosequencing techniques which target the V3-V4 region of the 16SrRNA gene. DS was found to be the most appropriate microlayer sampler, collecting larger volume of water samples at the shortest time possible and with least contamination from the UW. In addition, the diel changes of the bacterial communities in the SML and UW were also studied. This study have shown that samples collected using PC and GP were also different from the UW but are more susceptible to contamination from UW due to sampling errors and environmental conditions e.g. retrieval rate and wave action. Bacterial communities was found to have changed on a diel basis with a higher diversity at the SML during the day and similar diversity were found on both the layers during night time. This study has also revealed that the bacterial community richness and evenness are similar in the SML and UW but their diversity tends to be lower in the UW.

212 TUESDAY 10 SEPTEMBER 2013, 17:30 PS-2. Bacterial diversity: from community composition to community functions

PS-2.59. METAGENOMIC ANALYSIS OF MICROBIAL COMMUNITY IN TROPICAL LOWLAND PEATLANDS REVEALED SPECIALIZED FUNCTIONAL CAPABILITIES IN FRESHWATER ENVIRONMENT

Pui Yi Yung, National University of Singapore Coauthors: Umashankar S, Benke Imre P, Mishra S, Schuster S, Swarup S

Lowland peatlands in Southeast Asia cover 56% of the tropical and 6% of global peatland area. Peatlands have high water-holding capacity (up to 90% water) and have large impacts on the quality of the receiving waters. They normally act as , maintained by continuous organic matter inputs from tropical vegetation under water-logged conditions. Anthropogenic activities, for example drainage and deforestation, for the purposes of agriculture, have resulted in rapid increase of oxygen content in peat layer thus affecting the normal geochemical cycling in peatlands. This land use change has led to emissions estimated at 30-70 tonnes CO2 per hectare per year, excluding biomass losses due to forest fires. We have examined the microbial communities residing in degraded tropical peatlands of different land use (degraded forest, degraded land and oil palm plantation) in Eastern Sumatra, Indonesia. Analyses from metagenomics datasets were combined with physical and geochemical traits. Phylogenetic and functional capabilities of peatland microorganisms were characterized and compared with 20 metagenomes from other environments, such as lake, soil and freshwater. Putative genes encoding enzymes responsible for degradation of lignocellulosic biomass in the aerated zone of peat were also examined. Results have indicated the dominance of bacteria (under phyla Acidobacteria, Actinobacteria, Proteobacteria) as well as Archaea (both Euryarchaeota and Crenoarchaea) in the samples, and that the overall phylogenetic profiles of microbes between the three land use patterns were highly conserved. Genes under replication/repair, nitrogen metabolism, and carbohydrate metabolism were overrepresented in degraded land, plantations, and degraded forest, respectively. Specialized genes involved in methane and acetate metabolism were found. Comparative metagenomics have revealed that the peatland microbes were most similar to those found in environment with higher vegetative content. More than 50 Glycosyl hydrolase families were found, with the most abundant families being GH3, GH77, GH57, GH38, GH20 and GH5 (cellulose). A substantial amount of these genes are predicted to belong to Acidobacteria and Actinobacteria. Lignin oxidative enzymes, for example laccase (and related polyphenol oxidoreductases), different peroxidases, and lignin-degrading auxillary esterases, were also present. Indicating that the microbial communities have high capacity to degrade the recalcitrant peat biomass, leading to subsequent transformation and release of organic carbon into the atmosphere as well as the aqueous layer. A tentative model is being validated both by enzymatic assays and gas emissions analyses.

213 TUESDAY 10 SEPTEMBER 2013, 17:30 PS-2. Bacterial diversity: from community composition to community functions

PS-2.60. SUB-ALPINE LAKES DISPLAY DIFFERENT ARCHAEAL COMMUNITY STRUCTURES

Stéphan Jacquet, INRA CARRTEL, Thonon Les Bains (France) Coauthors: Berdjeb L, Pollet T, Chardon C

Archaeal communities’ dynamics and factors that constrain their structural variation are still poorly known in aquatic ecosystems. Here, we evaluated the driving forces exerted by a large set of environmental and biological parameters on the spatial and temporal dynamics of the archaeal community structure in two neighboring peri-alpine lakes which differ in terms of trophic status. We analyzed monthly data from a 2-year sampling period at two depths situated in the epi- and hypolimnion of each lake. Archaeal communities seemed to be composed of a very small number of abundant and widespread operational taxonomic units (OTUs) and a larger number of occasional OTUs, present at very low abundance indicating that the concept of “core” and “occasional” species could be applied to lacustrine archaeal communities. Their spatio- temporal dynamics was very similar in the two lakes with (i) disparities in the archaeal community structure in both time and space and (ii) no seasonal reproducibility from one year to another. Archaeal communities seemed to be regulated by complex combinations of biotic and abiotic factors. However, these factors explained, in most cases, less than 52% of the variance of archaeal community structure while they could explain from 70 to 90% of the temporal variance of bacterial communities (e.g. Berdjeb et al., 2011a). Clearly, this suggests that the archaeal community structure could be influenced by other factors than those implicated in the bacterial community structure and that, despite similar spatio-temporal dynamics, Bacteria and Archaea could occupy different ecological niches.

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MONDAY 9 SEPTEMBER 2013, 17:30 PS-3. Phototrophic plankton as the movers and shakers in aquatic ecosystems

PS-3.01. EFFECTS OF NUTRIENT LIMITATION ON COMPOUND SPECIFIC CARBON FIXATION IN PHYTOPLANKTON

Eric Boschker, Royal Netherlands Institute of Sea Research, Yerseke (The Netherlands) Coauthors: Grosse J

Like many coastal seas, the North Sea has been affected by eutrophication over the past decades and subsequent efforts to reduce riverine nutrient loads resulted in a major shift in N:P:Si nutrient ratios. The consequent effect on the stoichiometry and biochemical composition of phytoplankton can translate through the food web, affecting its structure, functioning, and consequently the carrying capacity of an ecosystem. Stable isotope tracers are widely used to estimate primary production in many ecosystems. However, beyond uptake rates limited emphasis is given to investigate into which of the major cellular compounds (amino acids, fatty acids, carbohydrates and DNA/RNA) the fixed carbon is allocated. Since all these compounds have different C:N:P requirements and therefore resource limitations should affect their biosynthesis differently. We combine GC-c-IRMS and novel LC-IRMS approaches to trace stable isotope incorporation into major cellular components, such as amino acids, fatty acids and carbohydrates, and determine their concentrations and biosynthesis rates. We applied these methods to samples from a transect in the North Sea, representing stations where different nutrients were expected to be limiting. The contributions of macromolecules to total biomass as well as their synthesis rates differed substantially between stations and the phytoplankton communities responded differently to nutrient additions by re-allocating fixed carbon to other macromolecules on short timescales (24 hours). These shifts were in agreement with a shift from phosphorus to nitrogen limitation between coastal and central North Sea stations. Though still preliminary, this work will allow us to infer changes in phytoplankton stoichiometry and consequent food web changes in response to nutrient availability.

215 MONDAY 9 SEPTEMBER 2013, 17:30 PS-3. Phototrophic plankton as the movers and shakers in aquatic ecosystems

PS-3.02. ECOLOGICAL EFFECTS OF LEVEL FLUCTUATIONS IN LAKE MAGGIORE, NORTHERN ITALY

Roberto Bertoni, CNR – ISE, Verbania (Italy) Coauthors: Callieri C, Contesini M

Global climatic changes increased the frequency of extreme events such as drought periods followed by heavy rains. We hypothesized that the level fluctuations occurring in Lake Maggiore, an oligotrophic deep lake in Northern Italy, could cause the release of pulses of phosphorus from the littoral zone, thus favoring cyanobacterial growth. The occurrence, in summer 2005, of a bloom of Anabaena lemmermannii, a species never encountered before in the of Lake Maggiore, could be the consequence of the unusual fluctuations of lake level.This bloom prompted us to experimentally evaluate the dynamics of accumulation and release of organic substance and nutrients from shores undergoing a succession of drought and flood events. Inert substrates were exposed at -0.5 m depth for around 30 days, moored 50 m from the coast. At recovery, the Particulate Organic Carbon and Nitrogen and the Particulate Inorganic Phosphorus accumulated on the inert substrates were measured. The lowering or rising of lake levels was simulated leaving the substrates to dry for 30 days and successively rewetting them in MQ water. Analyses of dissolved carbon and phosphorus released during 3 days of rewetting have been successively performed. This experiment was carried out from late spring to early autumn for two subsequent years.The results obtained showed that, along the perimeter of the lake (170 km), around 2 tons of organic carbon and 10 kg of phosphorus can accumulate monthly in the productive seasons. The composition of this material changes during the season, enriching in P over the summer. The appearances of A. lemmermannii blooms are coincident with a pulse of P and of organic material with C/N < 10 from the littoral. We observed this pattern over two successive years (2010 and 2011) when A. lemmermannii bloom appeared in the summer, after a heavy rain following a dry period of low-level. These results confirm our hypothesis of a relation between lake level fluctuations and cyanobacterial blooms.

216 MONDAY 9 SEPTEMBER 2013, 17:30 PS-3. Phototrophic plankton as the movers and shakers in aquatic ecosystems

PS-3.03. NODULARIN AND OTHER NON-RIBOSOMAL PEPTIDES PRODUCED BY NODULARIA SPUMIGENA STRAINS FROM THE BALTIC PROPER

Mireia Bertos-Fortis, Linnaeus University, Kalmar (Sweden) Coauthors: Mazur-Marzec H, Legrand C

Cyanobacterial blooms occur every summer in the Baltic Sea and are dominated by Nodularia spumigena, producer of the hepatotoxin nodularin and other bioactive peptides. During the last decades these blooms have increased, posing a threat to the ecosystem. Nodularia blooms are predicted to increase with increasing temperature, but little is known about the consequences of salinity decrease on these blooms and their production of bioactive compounds such as peptides. Three Nodularia spumigena strains (KAC11, KAC13, KAC66) isolated from the Baltic Proper, belonging to the same gene cluster were used as model species in this study. The aim was to determine nodularin levels at salinities 5 and 7, combined with peptide profiles using Liquid Chromatography-tandem Mass Spectrometry. Nodularin levels were different among the strains and salinities, but higher toxin concentrations were measured at lower salinity. Several structural variants of nodularins, spumigins, aeruginosins and anabaenopeptins (nodulapeptines) were identified, including 2 new peptide structures and 1 anabaenopeptin found for the first time in a Baltic strain. Peptide profiles described for KAC11 presented a higher diversity of compounds compared to KAC13 and KAC66. However, they were closely related when peptide patterns and genetic diversity were considered. The coupling of peptide profiles and genetic diversity needs to be investigated further by comparing populations from different geographical areas.

217 MONDAY 9 SEPTEMBER 2013, 17:30 PS-3. Phototrophic plankton as the movers and shakers in aquatic ecosystems

PS-3.04. PHYLOGENETIC DIVERSITY OF NON-MARINE PICOCYANOBACTERIA

Manuela Coci, CNR-Institute of Ecosystem Study, Verbania (Italy) Coauthors: Callieri C, Corno G, Macek M, Modenutti B, Balseiro E, Bertoni R

The most updated picture of the 16S rRNA phylogenetic tree of picocyanobacteria, including marine and freshwater strains, confirms the indication that Synechococcus 5.3 is not included in Synechococcus 5.1 but is its sister clade. The non-marine picocyanobacteria are considered as closely related to Cyanobium strains and proposed as monophyletic “Cyanobium-like” lineage. Nevertheless the relationships of these lineages to one another remain ambiguous. From this comes the need to enlarge the database with new sequences of isolated Synechococcus strains from a wider range of locations and environments to obtain a more realistic view of Synechococcus genus dispersal and evolution. In this study, we aimed to resolve better the Synechococcus phylogenetic tree enlarging the sequence data set of non-marine picocyanobacteria including strains isolated from “extreme” lakes. Therefore we selected four high altitude athalassohaline maar crater-lakes in Mexico as a source for “non-marine halotolerant” Synechococcus, five glacial ultraoligotrophic North Patagonian lakes as extreme ecosystems, and six Italian lakes of glacial, volcanic and morenic origin, with different trophic conditions. Our objective was to create a new phylogenetic tree of non-marine Synechococcus upgraded adding 43 new sequences derived from isolated picocyanobacteria and to refine the taxonomic relationships between non-marine Synechococcus clades and Synechococcus 5.2 and 5.3. The new sequences fall into a number of both novel and previously described clades within the phylogenetic tree of 16S rRNA gene. The new cluster of Lake Nahuel Huapi (North Patagonia) forms a sister clade to the subalpine cluster II and the marine Synechococcus sub-cluster 5.2. Our finding of the novel clade of “Halotolerants” close to the marine sub-cluster 5.3 (Synechococcus RCC307) constitutes an important demonstration that euryhaline and marine strains affiliate closely. The intriguing results obtained shed new light on the importance of the non-marine halotolerants in the phylogenesis of picocyanobacteria.

218 MONDAY 9 SEPTEMBER 2013, 17:30 PS-3. Phototrophic plankton as the movers and shakers in aquatic ecosystems

PS-3.05. DO TEMPERATURE AND RESOURCE AVAILABILITY AFFECT PHYTOPLANKTON SIZE STRUCTURE IN FJORDS?

Luis Antonio Cuevas, EULA-Chile Center, University of Concepcion (Chile) Coauthors: Vargas CA, Iriarte JL, Gonzàlez H, Silva N

Phytoplankton constitute the basis of the ecological food web and therefore play a major role in regulating inorganic nutrient availability, as well as in sustaining upper trophic levels in fjord ecosystems. Furthermore, temperature and resource availability (i.e. inorganic nutrients) have been suggested as important controlling factors affecting phytoplankton size structure, such that warming may increase the dominance of small cells and nutrient load (e.g. nitrogen) may stimulate the dominance of specific microphytoplankton groups. However, both stressors often covaries in aquatic ecosystems. Here we analyze data from five independent research cruisers covering the entire Patagonian fjords area (41.5-56.0º latitude South) to conduct a comparative analysis between zones and to determine the importance of the controlling factors on phytoplankton size structure. For the entire Patagonian area phytoplankton size structure varies with total phytoplankton biomass and productivity, but seems independent from temperature. Microphytoplankton contribute with ~80% in high productivity waters (chlorophyll-a higher than 5 mg L-1) independently of temperature, and picophytoplankton dominates when chlorophyll-a is lower than 1 mg L-1, mainly at temperate and warm waters. Oceanic nutrients such as nitrate and phosphate did not modify greatly the phytoplankton size structure, while the large decrease in fresh water nutrients e.g. Si(OH)4 (from 20 to 0.1 mM average from north to south, respectively) modify the phytoplankton size structure. Thus, Si(OH)4/NO3 < 1 shown more than 50% dominance of microphytoplankton cells, while Si(OH)4/NO3 > 1 shown tendency for picophytoplankton cells to dominate. Because resource availability and not temperature is the key factor explaining the relatively success of different phytoplankton size classes, we can assume that anthropogenic eutrophication greater than warming might modify the observed relationships, with the subsequence important changes in the phytoplankton community, its ecological role, and the fate of organic carbon.

219 MONDAY 9 SEPTEMBER 2013, 17:30 PS-3. Phototrophic plankton as the movers and shakers in aquatic ecosystems

PS-3.06. DMSP CELL QUOTAS FROM FLOW CYTOMETRICALLY-SORTED PHYTOPLANKTON FROM DIVERSE OCEANIC REGIONS

Giacomo Di Tullio, College of Charleston (United States) Coauthors: Lee P, Cyronak T, Kendrick J, Riseman S

Cellular quotas of various biogenic sulfur compounds in phytoplankton are a function of taxonomic class and physiological status of the organism. Biogenic sulfur compounds such as dimethylsulfide (DMS) are thought to be climatically active via the formation of cloud condensation nuclei. Numerical models to determine global DMS fluxes from the ocean to the atmosphere are dependent on knowledge concerning the intracellular concentration in various phytoplankton functional groups as well as the environmental factors that trigger the production of the DMS precursor, dimethylsulfoniopropionate (DMSP). However, species specific DMSP cell quotas from various natural oceanic environments are relatively unknown. Phytoplankton populations were collected from various oceanic provinces using a high speed cell sorter. These populations were then analyzed for the concentration of intracellular DMSP. For instance, a large bloom of Prorocentrum minimum off the Falkland Islands contained approximately 4 pg DMSP per cell. Flow cytometric abundance of Prorocentrum minimum at this site revealed a concentration of 12, 321 cells ml-1. This cell concentration suggested that P. minimum cells accounted for 815 nmoles L-1 of particulate DMSP. This value represented approximately 64% of the total DMSP measured at this site. Comparison between subtropical, temperate and polar oceanic systems revealed large differences in the cellular DMSP quota as a function of phytoplankton taxonomic group and cell size.Various environmental parameters such as nutrient limitation or viral infection also led to significant changes in cellular DMSP quotas.

220 MONDAY 9 SEPTEMBER 2013, 17:30 PS-3. Phototrophic plankton as the movers and shakers in aquatic ecosystems

PS-3.07. CELL DENSITY DEPENDENT OLIGOPEPTIDES PRODUCTION IN CYANOBACTERIAL STRAINS

Alessandra Giani, Universidade Federal de Minas Gerais, Belo Horizonte (Brazil) Coauthors: Pereira DA

Bacteria can communicate by releasing signalling molecules, a phenomenon known as quorum sensing, which stimulus is correlated to cell-population density. As a response, several modifications in the physiology of the bacterial population occur. Very little is known about quorum sensing in planktonic cyanobacteria. Because of their planktonic way of life, we would expect quorum sensing to be more evident at higher cellular density when cells would be closer to each other and their chance to communicate would increase, as for example during the occurrence of a bloom. In this work, we tested if cellular density could affect the production of some bioactive compounds produced by cyanobacteria. These are several oligopeptides, like microcystins, which functions are still being investigated. The experiments consisted of two treatments, where cultures of three different strains of cyanobacteria were maintained at low and high cellular density trough a semi-continuous set-up. Samples were periodically taken for measurement of growth rates, chlorophyll concentration, cell number and cell weight. At the end of the experiment, cultures were used for quantification and identification of the peptides. Analyses were performed by HPLC (Waters Alliance 2996) with a PDA detector (linear gradient run) and a MALDI-TOF Autoflex III mass spectrometer (Bruker Daltonics, Billerica, USA). Seventeen peptides were detected and 14 identified, including variants of microcystins, aeruginosins, cyanopeptolins and microviridins. The results showed that higher cellular density seems to have a significant effect on the production of the peptides. Most of the compounds (microcystins, aeruginosins, cyanopeptolins, and some unknown peptides) had significant higher cellular quotas in the higher cell density treatment, while microviridins and an unknown peptide were produced only at low density. Even if still preliminary, the results clearly suggest that quorum sensing may play a role in the production of cyanobacterial peptides.

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PS-3.08. TURN ON THE LIGHT: BENEFITS OF AEROBIC ANOXYGENIC PHOTOSYNTHESIS FOR THE ROSEOBACTER CLADE AFFILIATED (RCA) CLUSTER

Helge-Ansgar Giebel, University of Oldenburg, ICBM (Germany) Coauthors: Wemheuer B, Voget S, Simon M

Photoheterotrophy is a surprisingly common feature among the main bacterioplankton groups. Within Alphaproteobacteria quite a few representatives of the Roseobacter clade are known to carry genes encoding bacteriochlorophyll a (BChla) and thus are capable of aerobic anoxygenic photosynthesis (AAnP). However, still little is known about the genomic organisation and expression of these genes in the major bacterioplankton groups including the Roseobacter Clade Affiliated (RCA) cluster and, more importantly, about potential benefits of this complementary energy source. Genomic analyses of the RCA type strain Candidatus Planktomarina temperata revealed the presence of the entire BChla operon. The RCA specific photosynthetic operon was present in different metagenomic libraries of other studies, from a Norwegian fjord, the western English Channel, the western coastal Atlantic and the eastern and western Pacific. During a metatranscriptomic study of environmental samples in the German Bight (North Sea) we were able to show the expression of the RCA photosynthetic operon, pointing to the biosynthesis of BChla in situ and thus to generating energy via AAnP by RCA microbes. To examine more specifically effects of AAnP on the growth of Cand. P. temperata we carried out growth experiments in a light-dark cycle versus dark conditions. During the exponential growth phase there was no difference between both conditions. However, in the stationary phase, cell numbers grown in the light-dark cycle remained twice as high as in the dark and the cell size and its granularity of the former was significantly lower compared to the dark. First results of RT-PCR analysis indicated the expression of photosynthetic pufM genes for Cand. P. temperata during these experiments.

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PS-3.09. PLANKTON DYNAMICS IN PATAGONIAN FJORDS: THE INFLUENCE OF TERRESTRIAL VERSUS OCEANIC MICRO- (FE) AND MACRO-NUTRIENT (N, P) IN THE MAGNITUDE AND FATE OF THE PRIMARY PRODUCTION

Humberto Gonzàlez, Universidad Austral de Chile, Institute of Marine and Limnological Sciences, Valdivia (Chile) Coauthors: Iriarte JL, Murat A, Cuevas A, Sanchez N, Castro L, Daneri G, Giesecke R, Silva N

Patagonian systems constituted a “mix” between terrestrial and oceanic influences. The phytoplankton biomass and primary production (PP) showed a highly seasonal variability where during spring, the high PP was dominated by large diatoms and the main flow occurred through the classical (traditional) food web. During winter the PP was mainly channeled through the microbial food web and a high amount of the available organic matter would be of allochthonous origin and introduced via freshwater discharge. The highly PP showed in spring has been associated with efficient export production to the sediments, suggesting that the Chilean fjord region could be a major “CO2 sink” during the productive season. The aim of this study was to contribute with information on the processes/factors that modulate the efficiency of the “biological carbon pump”. This challenge was tacked through experiments of nutrient addition (Fe and changing N:Si and N:P ratios) to follow the evolution of autotrophic biomass, possible shift in species or functional groups and the effect on vertical flux of particulate organic carbon. Preliminary results show relatively very low dissolved Fe concentrations (2 to 3 nM) at the photic zone, which may represent the preliminary evidence of iron deficiency in waters of Comau fjord during summer period (December - March). Concentrations of different types of iron (TFeCh, DFeCh and FeDGT) in a river to fjord transect showed that riverine constituted a main source, presenting the highest values at river mouth and the lowest at the middle of the fjord. Concentrations ranged -1 -1 -1 122.8 to 42.2 nmol L , 36.7 to 16.5 nmol L and 5.0 to 1.0 nmol L for TFeCh, DFeCh and FeDGT fractions, respectively. The main implications of this study were: (1) The pivotal role of the freshwater and oceanic subantarctic water in the modulation and fate of the PP, through the input of silicic acid+DOM/POM and nitrate+orthophosphate, respectively. (2) The role of constriction/sill in modulating the PP through the freshwater versus oceanic water distribution. This affects the dominance of small versus large phytoplankton and in turn the channeling of the carbon through the microbial versus traditional food webs in winter and spring seasons, respectively. This study was funded by Grant FONDECYT 1110614, WAFOW/NTNU and CONA, programs CIMAR 17 and 18.

223 MONDAY 9 SEPTEMBER 2013, 17:30 PS-3. Phototrophic plankton as the movers and shakers in aquatic ecosystems

PS-3.10. AUTOTROPIC DINOFLAGELLATES APPARENTLY OBLIGATE RELIANCE ON HETEROTROPHIC BACTERIA

David Green, Scottish Association for Marine Science, Oban (Scotland) Coauthors: Subramanian TA, Bolch CJS

Marine dinoflagellates are a diverse lineage of phytoplankton of significant ecological and economic importance, and they have been described as a “remarkable evolutionary experiment”. Another remarkable feature of this “experiment” is a growing body of evidence that dinoflagellates have a strong dependence on heterotrophic bacterial presence for them to be able to live and thrive. Such a dependency has been observed for two heterotrophic species, Oxyrrhis and Pfiesteria, and a single autotrophic species, Gymnodium catenatum. In this paper we present evidence that this includes a further two species of autotrophic dinoflagellate, Scrippsiella trochoidea and Lingulodinium polyedrum. All three autotrophic species have an apparently obligatory requirement for bacteria to be present when the dinoflagellate transitions from dormancy to vegetative growth, and G. catenatum continues to require bacteria for its vegetative growth. Data describing the different bacteria that meet this requirement and general observations on this relationship will be presented. The potential ecological and evolutionary relevance of this interaction will be discussed, along with the value of such tractable models for study of algal-bacterial interactions, biogeochemistry and their biotechnological application.

224 MONDAY 9 SEPTEMBER 2013, 17:30 PS-3. Phototrophic plankton as the movers and shakers in aquatic ecosystems

PS-3.11. ACTIVE GROWTH OF AEROBIC ANOXYGENIC PHOTOTROPHIC BACTERIA IN SEASONAL SEA ICE OF SAROMA-KO LAGOON, NORTHERN JAPAN

Koji Hamasaki, Atmosphere and Ocean Research Institute, University of Tokyo (Japan) Coauthors: Koike I, Tada Y, Taniguchi A, Kogure K

Aerobic anoxygenic phototrophic bacteria (AAnPB) were firstly isolated from seaweeds on the coast of Japan in 1970s. Their ubiquitous distribution in marine pelagic environment has been clarified since the rediscovery of their abundance in the eastern Pacific in 2000. Microbial communities in sea ice are known to show high metabolic activity in spite of its extreme environment. Recently, AAnPB has been found in antarctic sea ice, expressing the gene of bacteriochlorophyll-binding protein, pufM. However, it still remains unknown about their abundance and dynamics in sea ice microbial communities. Here, we report abundance and active growth of AAnPB in seasonal sea ice in comparison with its underlying water and other coastal waters. Sea ice and underlying water samples were collected in March 2007 in Saroma-ko Lagoon, Hokkaido, Japan. Coastal seawater samples were collected in July 2008 in Sagami Bay. Collected seawater and melted sea ice were filtered onto 0.22 μm pore-size membranes and subjected to DNA extraction and quantitative PCR (QPCR) of the pufM gene. The bromodeoxyuridine(BrdU)- labeling and immunocapture technique was used to quantify actively growing AAnPB. The copy number of the pufM gene in sea ice was higher than that in underlying seawater and coastal water of Sagami Bay. The analysis of BrdU-labeled DNA revealed that actively growing AAnPB were more abundant in sea ice than in the seawater. Also, actively growing AAnPB abundance showed positive correlation to chlorophyll-a concentration, suggesting the importance of organic matter supply as a factor of controlling their dynamics in sea ice. In this study, we have found active AAnPB in temperate summer seawater of Sagami Bay and seasonal sea ice of Saroma-ko Lagoon where water temperature rises up to 20 oC in summer, implying eurythermal natute of AAnPB supports their ubiquitous distribution in marine environment. QPCR of specific functional genes in combination with the BrdU-labeling technique as was shown in this study can be a powerful tool for studying the dynamics of bacterial functional groups in natural environments.

225 MONDAY 9 SEPTEMBER 2013, 17:30 PS-3. Phototrophic plankton as the movers and shakers in aquatic ecosystems

PS-3.12. POPULATION AND COMMUNITY RESPONSE OF PHYTOPLANKTON TO NUTRIENT AND IRON-ORGANIC MATTER COMBINATIONS IN A CHILEAN PATAGONIAN FJORD

Jose Luis Iriarte JJ, Universidad Austral de Chile, Puerto Montt (Chile) Coauthors: Ardelan M, Cuevas LA, González HE, Sanchez N, Navarro J, Espinoza M, Cisternas B, Gomez P, Inostroza I, Myklestad SM

The highly productive Patagonian fjords have been recognized as a major region where iron- organic matter forms may be essentials complexes involved in key growth processes connected to the carbon and nitrogen cycles. Dissolved organic matter (DOM), in coastal waters can have negative/positive effect on microalgal growth through iron limitation induced by its complexation with iron. Thus it is relevant to study how the availability of organically bound Fe modulates the growth of blooming phytoplankton species. We used a diatom polysaccharide and bacterial , as DOM models to understand how do they affect the bioavailability of Fe of blooming phytoplankton communities and to assess their ecological role in fjord systems. In addition, we evaluated the importance of siderophore threshold concentrations in controlling Fe bioavailability for key blooming phytoplankton populations of coastal waters of Patagonia. Two approaches were performed: (1) a 10-days microcosm study was performed in the Comau Fjord during summer conditions (March 2012). Pico-, nano-, and microphytoplankton abundance, total chlorophyll-a, bacteria abundance, and bacterial secondary production estimates were analyzed in five treatments. At Nutrients + Fe and polysaccharide treatments, chlorophyll-a concentration abruptly increased from 0.9 to 20 mg m-3 during the first 4-6 days of the experimental period. Remarkably, at the Nutrients + Fe treatment, the development of the bloom was accompanied with markedly high abundances of Synechococcus, picoeukaryotes, and autotrophic nanoflagellates within the first four days of the experiment. Thus small-size plankton groups were the first to respond to dissolved Nutrients + Fe compared to micro-phytoplankton cells. (2) Fe complexation experiments, under a gradient of different concentration of siderophore were carried out using two species of phytoplankton: the toxic dinoflagellate Alexandrium catenella and the centric diatom Skeletonema sp., both isolated from Patagonia fjords waters. The growth of Skeletonema sp. was inhibited by high iron level (5 nM) it was complexed at high siderophore levels (1 - 2 nM). For A. catenella, iron availability was not affected by the presence of siderophore . The results support the idea that bioavailability of iron depends not only on ligand sources, but also on their concentrations. In summary, our results suggest that the effects of Fe-DOM complexation, and therefore iron availability), are different among phytoplankton species as well as among functional groups which could be determinant in modulating the uptake of iron complexed with DOM and the formation and dominance of specific phytoplankton species/assemblages in coastal waters off Patagonia. Funding by Grant FONDECYT 1110614

226 MONDAY 9 SEPTEMBER 2013, 17:30 PS-3. Phototrophic plankton as the movers and shakers in aquatic ecosystems

PS-3.13. HOW AUTUMN CIRCULATION AFFECTS THE DISTRIBUTION OF PROKARYOTIC PLANKTON?

Natalia Jakubowska, Department of Water Protection, Adam Mickiewicz University, Poznań (Poland) Coauthors: Napieralska A, Szelag-Wasielewska E

The autumn circulation also known as "deep breath lake" leads to the compensation of dissolved gases, electrolytes and temperature in lakes water column. This circulation is thus a major factor which influence on water microorganisms including bacterioplankton and autotrophic picoplankton (0.2-2.0 μm). Here we present a results of studies on the abundance of prokaryotic plankton (heterotrophic bacteria, phototrophic bacteria and picocyanobacteria) carried out during a stratification and circulation of water lake. The aim of this studies was how the autumn circulation determines the vertical distribution of prokaryotic organisms in Strzeszyńskie Lake in September and December 2011. The Strzeszyńskie Lake (max depth 17.8 m) is located in western Poland. The lake has an area of 34.9 ha, a volume of 2.8 106 m3, a maximum depth of 17.8 m and a mean depth of 8.2 m. The Strzeszyńskie Lake is dimictic with thermal stratification between May and October. In deepest place of the lake were measured: temperature, pH, oxygen content and conductivity in the whole water column at 1 m intervals with the use of the multiparameter sonde. In the same station water samples for analysis of prokaryotic plankton were taken every 2 m. The samples were preserved with buffered formaldehyde to the final concentration of 1-2%. Bacteria was concentrated on polycarbonate black filters (0.2 µm pore size) and after staining fluorochrome DAPI, the samples were analyzed using fluorescence (Olympus BX-60) microscope at 1500x magnification. During the summer stratification, the average number of heterotrophic bacteria in the water column was 27.1·105 cells·ml-1, the average number of phototrophic bacteria amount to 0.55·105 cells·ml-1 and picocyanobacteria 2.2·105 cells·ml-1. The maximum abundance of heterotrophic bacteria (48.3·105 cells·ml-1) as well as phototrophic bacteria (2.6·105 cells·ml-1) were observed at a depth of 14 m. The greatest number of picocyanobacteria (4.8·105 cells·ml-1) was noted in the metalimnion at the depth of 6 m as opposed to heterotrophic bacteria, which there was least number of all. The number of the phototrophic bacteria increased from the depth of 8 m, replacing the declining numbers of picocyanobacteria. These fluctuations were not observed during the water circulation. In this period the number of picocyanobacteria ranged from 0.097·105 to 0.18·105 cells·ml-1. Furthermore the number of heterotrophic bacteria increased by up to 87% compared to the period of stratification.

227 MONDAY 9 SEPTEMBER 2013, 17:30 PS-3. Phototrophic plankton as the movers and shakers in aquatic ecosystems

PS-3.14. TEMPERATURE CONSTRAINS DISTRIBUTION OF ANOXYGENIC PHOTOTROPHS

Michal Koblizek, Institute of Microbiology AS CR, Trebon (Czech Republic) Coauthors: Medova H, Masin M, Kaftan D

Anoxygenic phototrophs are one of the oldest life forms on Earth. During their long evolution these organisms had to adapt to diverse environmental conditions including a wide span of ambient temperatures. We investigated the influence of temperature on the distribution of aerobic anoxygenic phototrophs (Proteobacteria) in various habitats representing a wide span of temperatures. In several seasonal studies it was found that these organisms proliferated at temperatures above 8°C. On the other side of the temperature extreme it seems that phototrophic Proteobacteria cannot grow at temperatures above 50°C. This is different from other phototrophic phyla such as cyanobacteria or green nonsulfur phototrophic bacteria which thrive even above 70°C. To explain observed pattern we investigated the thermal characteristics of photosynthetic reaction centers of phototrophic Proteobacteria using molecular dynamic simulations. The analysis of available structural data suggested that the stability of the reaction centers largely depend on their tertially structure stabilization through weak interhelical van der Waals interations. The bulky molecular design of their reaction centers seems to represent an example of an evolutionary constraint, which prevents the evolution of truly psychrophilic or extreme thermophilic species.

228 MONDAY 9 SEPTEMBER 2013, 17:30 PS-3. Phototrophic plankton as the movers and shakers in aquatic ecosystems

PS-3.15. EVOLUTION OF THE MARINE PHYTOPLANKTON OSTREOCOCCUS TAURI IN THE FACE OF MULTIPLE STRESSORS

Lawrence D, Coauthors: Collins S

Photosynthetic marine algae are key components of the global carbon cycle and marine foodwebs, yet few experiments have investigated how they are likely to evolve in the face of climate change and ocean acidification. We use experimental evolution with Ostreococcus tauri to investigate how marine algae evolve in response to multiple stressors including elevated carbon dioxide, temperature and acidity and how this influences their capacity to store carbon. Furthermore, we collaborate with oceanographers and modellers to determine what our findings in the laboratory can tell us about the impacts of climate change on marine ecosystems and carbon storage in the future.

229 MONDAY 9 SEPTEMBER 2013, 17:30 PS-3. Phototrophic plankton as the movers and shakers in aquatic ecosystems

PS-3.16. INTERACTIONS BETWEEN HETEROTROPHIC BACTERIA AND A TOXIC CYANOBACTERIUM, PLANKTOTHRIX RUBESCENS, IN VICO LAKE, CENTRAL ITALY

Maura Manganelli, Istituto Superiore di Sanità, Rome (Italy) Coauthors: Stefanelli M, Scardala S, Funari E

Vico Lake, central Italy, is a mesotrophic lake interested by frequent blooms of the toxic cyanobacterium (CB) Planktothrix rubescens. In the lake, this is the dominant species of phytoplankton community and it’s always present during the year, moving below the thermocline during 2-3 summer months. Few data are available on interactions between bacteria and P. rubescens in lakes, which suggest that in oligotrophic environments recycling activity of bacteria can support P. rubescens blooms. Since P. rubescens produces microcystins, non ribosomal peptides toxic to eukaryotes, it can either represents an important source of carbon or a selective force on bacterial community. We conducted a two years field sampling from two coastal sites and from one at the deepest point of the lake (max depth of 40m), from three depths, surface, -20m (below the thermocline) and bottom. We looked at the relationship between P. rubescens and heterotrophic bacterial community, by measuring P. rubescens, bacterial and viral abundance, bacterial production (BCP), ectoenzymatic activities and toxin production. BCP, aminopeptidase (AMA), lipase (Lip) and alkaline phosphatase (APA) were measured on the total samples and on <5micron fraction, to assess the relative contribution of free and attached bacteria.

230 MONDAY 9 SEPTEMBER 2013, 17:30 PS-3. Phototrophic plankton as the movers and shakers in aquatic ecosystems

PS-3.17. POPULATION GENETICS OF THE HARMFUL CYANOBACTERIUM MICROCYSTIS AERUGINOSA REVEALS HIGH DIVERSITY, INTERANNUAL REDUNDANCY AND INTRASPECIFIC SEED-BANK OF UBIQUITOUS GENOTYPES

Benjamin Misson, LMGE, Université Blaise Pascal, CNRS, Aubière (France) Coauthors: Sabart M, Jobard M, Duffaud E, Amblard C, Latour D

In aquatic ecosystems, microbial biodiversity has been the subject of numerous studies. However, this biodiversity has scarcely been studied at the intraspecific level, in spite of its relevance for the comprehension of species ecology. Such paradox is particularly true for phytoplankton, including the cyanobacterium Microcystis aeruginosa, which is one of the most widespread harmful freshwater cyanobacteria. To improve our understanding of the genetic structuration of natural populations of M. aeruginosa at annual and interannual scale, we studied four different annual blooms (corresponding to 2003, 2006, 2007 and 2009) that developed in the Grangent reservoir (France). We used adapted methods for investigating genetic diversity at the intraspecific scale (cloning and sequencing of the 16S-23S ITS), and we considered both the benthic and the planktonic life stages of M. aeruginosa. Whatever the year, the genotypic structure of the population of M. aeruginosa developing in the Grangent reservoir always showed a high temporal variability, with the succession of various dominant genotypes during a single bloom. By pooling the results of the four blooms, we demonstrated that, although the population consisted in a high number of different genotypes, only a few number dominated the biomass of the different blooms and were quite redundant from one year to another. Most of these abundant genotypes were observed in both water and sediment of Grangent reservoir, and the comparison of their sequences with public databases revealed that some of them had previously been encountered in other lakes from other countries and continents. Thus, these genotypes seem to be able to develop or resist to highly contrasted environments. Surprisingly, in Grangent reservoir, every abundant genotype also proved to be punctually rare (< 5% of the sequences), thus demonstrating that the pool of rare genotypes could represent a real seed-bank for the population. All these results demonstrate the high adaptive potential of M. aeruginosa and suggest an intraspecific version of both rare/abundant and seed-bank concepts. Taken together, these new findings could explain the ecological success of this cyanobacterium.

231 MONDAY 9 SEPTEMBER 2013, 17:30 PS-3. Phototrophic plankton as the movers and shakers in aquatic ecosystems

PS-3.18. IMPACT OF THE VISTULA RIVER ON NANOPHYTOPLANKTON COMMUNITIES IN THE BRACKISH WATERS OF THE GULF OF GDAŃSK (SOUTHERN BALTIC SEA)

Kasia Piwosz, National Marine Fisheries Research Institute, Gdynia (Poland) Coauthors: Calkiewicz J, Golebiewski M, Creer S

Marine and fresh waters are very distinct habitats for microorganisms, and thus they harbour different microbial communities. River estuaries are places were marine and freshwater microbes are forced to meet, but severe environmental conditions: steep gradients of physico-chemical factors and tides-driven dynamics of water masses, prevent their long-time coexistence. However, in the brackish, tide-less Baltic Sea, the Vistula Rivers leisurely introduces its waters to the Gulf of Gdańsk. The gradual mixing of marine and riverine waters and lenient salinity gradient (salinity (S) range from 0 to 7 PSU) allow for co-existence of marine and freshwater microbes. Here, we investigated communities of nanoplanktonic eukaryotes in estuary of the Vistula River: in freshwaters (S<0.1 PSU) and mixing zone(S≈3.5 PSU), and of marine (S>7 PSU) waters of the Baltic Sea by 454 sequencing of 18S rRNA (with environmental RNA as the template). We hypothesised that the specific conditions of the Gulf of Gdańsk will allow for survival of freshwater phylotypes not only in the mixing zone, but also in the marine waters. We found that the mixing zone was more influenced by species of freshwater origin rather than by marine ones. Marine communities were significantly distinct from freshwater and in the mixing zone, with only minimal contribution of phylotypes that were present in riverine waters. More detailed analyses of two phototrophic groups: cryptophytes and chlorophytes, showed that such separation occurs not only at the OTU level, but also at order and class level.

232 MONDAY 9 SEPTEMBER 2013, 17:30 PS-3. Phototrophic plankton as the movers and shakers in aquatic ecosystems

PS-3.19. ENVIRONMENTAL FACTORS CONTROLLING DIATOM PRIMARY PRODUCTIVITY: THE ROLE OF SILICA IN CARBON ACQUISITION

Tamsyne Jade Smith-Harding, Flinders University School of Biological Science (Australia) Coauthors: Mitchell JG, Beardall J

Diatoms are the dominant marine primary producers generating approximately 40% of oceanic organic carbon. They have an absolute silicate requirement for frustule formation. The silica in the frustule may be a buffer for external carbonic anhydrase (CAext), an enzyme that plays a crucial role in improving the supply of CO2 for use by RubisCO, the rate-limiting step in carbon fixation. The aim of the current work is to investigate the impact of silica limitation on CAext activity. We hypothesise that diatoms with a more robust frustule, acting as a buffer, will have greater CAext activity than diatoms with little or no silica. As a result, they will perform photosynthesis at a faster rate. We investigated the relationship between the frustule and CAext activity in Phaeodactylum tricornutum and Thalassiosira pseudonana. Biosilica content, CAext activity and the rate of photosynthesis were measured for each species. We found that the biosilica content of T. pseudonana was 4x higher than that of P. tricornutum. In support of our hypothesis we found that T. pseudonana had up to 50% greater CAext activity, and a greater rate of photosynthesis. Whilst these preliminary results are promising, more research is needed to establish a stronger link between frustule robustness and CAext activity. Current work is in progress to investigate whether this relationship between more robust frustules, CAext and overall photosynthesis holds true for diatom species subjected to silica limitation.

233 MONDAY 9 SEPTEMBER 2013, 17:30 PS-4. Bacterial life strategies in relation to carbon flow to higher trophic levels

PS-4.01. ECOLOGICAL RELEVANCE OF PHOTOHETEROTROPHIC BACTERIA IN THE WESTERN ARCTIC OCEAN

Dominique Boeuf, Station Biologique de Roscoff - CNRS / UPMC (France) Coauthors: Cottrell MT, Lami R, Kirchman DL, Jeanthon C

Heterotrophic bacteria are crucial components of marine food webs and have key roles in controlling carbon fluxes in the oceans. Aerobic anoxygenic phototrophic (AAP) bacteria and proteorhodopsin (PR)-containing bacteria can depart from a strictly heterotrophic lifestyle by obtaining energy through unconventional mechanisms that are linked to the penetration of sunlight into surface waters. These photoheterotrophic mechanisms may play a significant role in the energy budget in the euphotic zone of marine environments. Our knowledge of photoheterotrophic bacteria is largely incomplete, especially in high-latitude marine waters. In this study, we examined the abundance (infrared epifluorescence microscopy and quantitative PCR), activity and diversity of both photoheterotrophic communities in the western Arctic Ocean where environmental changes could favor the photoheterotrophic lifestyle. AAP bacteria comprised up to 10 and 14% of the prokaryotic community in the bottom nepheloid layer and surface waters of the Mackenzie plume, respectively, but were low in Beaufort Sea offshore waters. The most frequent AAP group was a new uncultivated betaproteobacterial clade whose abundance decreased along the salinity gradient of the Mackenzie plume even though its photosynthetic genes were actively expressed in offshore waters. Our data indicate that AAP bacterial assemblages represented a mixture of freshwater and marine taxa mostly restricted to the Arctic Ocean and highlight the substantial influence of riverine inputs on their distribution in coastal environments. Depth profiles showed that PR-containing bacteria were abundant throughout the water column, comprising up to 44% of total bacteria, although they varied greatly with location and depth. On average, they made up 15% of the bacterial community. Alphaproteobacteria dominated the PR community in all water masses of the Beaufort Sea with SAR11 as the major PR type. Substantial overlap between DNA and cDNA libraries indicated in situ PR transcription for a large fraction of PR-containing community. Our results suggest that PR phototrophy provides to oligotrophic and copiotrophic bacteria a competitive advantage that help them to exploit the heterogeneity of the marine environment. This study demonstrates that bacteriochlorophyll a- and PR-based phototrophic likestyles are significant and active processes in the Arctic Ocean, probably having important ecological roles in this extreme environment.

234 MONDAY 9 SEPTEMBER 2013, 17:30 PS-4. Bacterial life strategies in relation to carbon flow to higher trophic levels

PS-4.02. DECREASE OF BACTERIAL GROWTH EFFICIENCY AFTER DOM MODIFICATION BY PROTOZOAN GRAZING IN SEAWATER

Zuriñe Bana Z, University of Basque Country, Bilbao (Spain) Coauthors: Ayo B, Marrasé C, Gasol JM, Iriberri J

In trying to understand how different types of DOC/DOM regulate the response of bacteria, we explored how the DOM altered by bacterial growth, and that altered both by bacterial growth and the subsequent protozoan grazing will affect the major metabolic features of bacterial communities from coastal waters of the SE Cantabrian Sea (CS) and the NW Mediterranean Sea (MS). Bacterial respiration (BR), bacterial production (BP), bacterial carbon demand (BCD), bacterial growth efficiency (BGE) and extracellular enzymatic activities (EEA) were measured in treatments in which half of the natural water was replaced by water collected from different key times of the predator-prey curve, which were compared to controls in which natural DOM was available for bacteria. In both ecosystems, the altered DOM obtained after intensive grazing by protozoa led to similar increases in cell-specific BCD (up to 238% and 213%), as well as similar decreases in BGE (up to 56% and 46% for the CS and the MS respectively). These low BGEs were caused by similar production rates, but much higher respiration rates. In this sense, we found a positive relationship between the enhancement of the cell-specific aminopeptidase activity (AMP) and the increased cell-specific BR. This extra metabolic cost associated to higher hydrolytic capacity in response to the new DOM altered by protozoa was in turn closely related to the remarkable differences in the bacterial community composition (BCC) between both ecosystems. The bacterial community of the CS, dominated by Bacteroidetes (41%), showed a lower metabolic cost associated to the enhanced hydrolytic activity than the bacterial community of the MS, dominated by SAR11 (47%), which suggest a better adaptation potential of the Bacteroidetes to the DOM altered by the protozoan grazing. Our results indicate that: i) grazing by protozoa is a relevant factor influencing BGE in coastal ecosystems and ii) the metabolic processes that result after a change in marine DOM are closely related to and dependent upon BCC.

235 MONDAY 9 SEPTEMBER 2013, 17:30 PS-4. Bacterial life strategies in relation to carbon flow to higher trophic levels

PS-4.03. EVALUATION OF METHODS TO DETERMINE PROTIST-DRIVEN MORTALITY OF PROKARYOTES, AND THE INTRODUCTION OF A NEW VARIANT OF A WELL-KNOWN PREY ANALOG

Alexander Bochdansky, Old Dominion University, Norfolk (United States)

The predation of eukaryotic microbes on prokaryotes is one of the most important trophic interactions on Earth. Together with viral infections, bacterivory represents one of two major loss terms for prokaryotes, and shapes the morphology and composition of prokaryotic communities. Hundreds of studies have used a wide variety of methods exploring the relative role of a pathway that transfers material and energy from DOM to higher trophic levels. Methods applied thus far have either targeted feeding rates of individual protists, or examined the effect of predation on total prokaryote communities. At first sight, the variability among methods seems high. However, at closer look the rate constants of mortality (i.e., the instantaneous mortality coefficients) vary surprisingly little across a wide range of environments perhaps as the result of physical constraints and threshold dynamics in predator - prey interactions. Here I present a variation of a model particle that has been successfully used as a prey analog over several decades: minicells of Escherichia coli. A major improvement was their modification with a bright GFP vector. This new prey analog has many advantages including high stability against microbial and light degradation, procedural simplicity, low costs even when produced in mass quantities, and no chemical alteration of the particle surface due to a staining procedure. Rate measurements using this prey analog are consistent with a diverse array of methods such as the dilution method, a trophic cascade method, and the use of DTAF-stained prey.

236 MONDAY 9 SEPTEMBER 2013, 17:30 PS-4. Bacterial life strategies in relation to carbon flow to higher trophic levels

PS-4.04. FLOW CYTOMETRY APPLICATION FOR ECOPHYSIOLOGICAL STUDIES IN THE PHOTOSYNTHETIC PURPLE SULFUR BACTERIUM CANDIDATUS “THIODICTYON SYNTROPHICUM” SP. CAD16

Francesco Danza, Laboratorio di Microbiologia Applicata, Bellinzona (Switzerland) Coauthors: Tonolla M

Flow cytometry is becoming an essential tool in aquatic microbiology. Due to the opportunities of rapid data acquisition and multiparameter analysis, flow cytometry application in the microbiology field range from cell counts to physiological analysis. In this study, flow cytometry was applied to characterize and describe the metabolic activity of the phototrophic purple sulfur bacterium (PSB) Candidatus “Thiodictyon syntrophicum” sp. CAD16 subjected to different nutritional states during laboratory experiments. PSB CAD16 has been isolated from the chemocline of the meromictic subalpine Lake Cadagno (Switzerland). Our interest in this PSB strain derives, as recently demonstrated (Storelli et al., 2013), by its central role played in the ecology of Lake Cadagno - the contribution of PSB CAD16 to the total primary production in the chemocline of the lake resulted to be up to 25%. The draft (7.3 Mbp) PSB CAD16 genome reveals a highly flexible physiology that potentially allows Candidatus “T. syntrophicum” CAD16 strain to adapt to broad lifestyles in aquatic environments. In phototrophy, purple sulfur bacteria oxidize hydrogen sulfide (H2S) to 2- elemental sulfur (S) that can act as storage compound to be further oxidized to sulfate (SO4 ) generating reducing power required for growth. Chemotrophy can be an additional and alternative metabolic strategy used by PSB CAD16. Laboratory growth unstained samples of our PSB CAD16 model strain analysed using a blue laser-based flow cytometer provided the detection of intracellular sulfur accumulation dynamics during autotrophy (sulfide and bicarbonate as, respectively, energy and carbon source) and mixotrophy (sulfide, bicarbonate and acetate), as sulfur accumulation changed the light scatter characteristics of the cells. Interestingly, flow cytometry data also allowed the recognition of storage carbon compounds dynamics generated during both auto- and mixotrophy in the presence or absence of light. Flow cytometry resulted to be a fast and accurate technology for the identification and characterization of metabolic status and the activity rate of phototrophic purple sulfur bacteria population in a defined environment.

237 MONDAY 9 SEPTEMBER 2013, 17:30 PS-4. Bacterial life strategies in relation to carbon flow to higher trophic levels

PS-4.05. TESTING MICROBIAL PRIMING: CONTRASTING EFFECTS OF LABILE DOC ADDITION ON PLANKTON DEPENDING ON PRESENCE OF FISH IN A HUMIC BOREAL LAKE

Irene Dorado-Garcia, Institute of Water Research, University of Granada (Spain) Coauthors: Syväranta J, Devlin Shawn P, Medina-Sánchez JM, Jones RI

Many boreal lakes receive high inputs of recalcitrant allochthonous dissolved organic carbon (DOC), especially from surrounding peatlands. We investigated the threshold of added labile DOC necessary to promote a priming effect (i.e. stimulation of bacterial metabolism with a subsequent increase in the mineralization of recalcitrant DOC), and the changes in microbial structure (algae and bacterial abundance) and function (primary and bacteria production) promoted by a gradient of increasing labile DOC. Our investigation was carried out in a small highly humic lake (Mekkojärvi, southern Finland). As part of a larger project the lake had been divided by a plastic curtain into two experimental sides, one with presence of fish (+FISH) and the other fishless (- FISH). On each experimental side we performed a factorial experiment in which different amounts of labile DOC as cane sugar (control, +6, +9, +12mgC L-1) were supplied to 8L mesocosms. These enclosures were sampled 24h, 3days and 5days after carbon addition. Our results show that carbon addition did not stimulate bacterial production, regardless of fish treatment. However, there was a DOC decrease in the FISH treatment suggesting that this carbon was readily consumed, but that consumption was insufficient to lower DOC concentrations beneath those in the control. Heterotrophic bacterial abundance differed depending on FISH treatment and time, showing higher values in FISH at shorter times. Mixotrophic algae abundance increased in all DOC treatments in FISH. Chl a increased only in -FISH after 3 and 5 days, while in +FISH treatments there were no significant changes. Primary production was higher in 9 and 12mgC L-1 carbon additions in +FISH treatments but otherwise did not differ fer between treatments. In conclusion, added labile DOC did not support the triggering of a priming effect regardless of fish treatment. However, the higher bacterial abundance in the absence of fish might sustain the higher proportion of mixotrophs found in the algal community, suggesting a possible trend towards a higher mixo-heterotrophy of plankton with increasing availability of labile DOC in fishless humic lakes.

238 MONDAY 9 SEPTEMBER 2013, 17:30 PS-4. Bacterial life strategies in relation to carbon flow to higher trophic levels

PS-4.06. CRYPTIC ELEMENTAL CYCLING IN ROSEOBACTER-PHYTOPLANKTON ASSOCIATIONS

Bryndan Durham, University of Georgia, Athens (USA) Coauthors: Sharma S, Smith C, Amin S, Armbrust V, Moran MA

Marine bacteria and phytoplankton control one of the largest active carbon reservoirs on Earth through the processes of fixation, mineralization, and sequestration. Direct interactions between these plankton groups may have significant impacts on the carbon cycle, as marine bacteria often occur in higher densities in phycospheres and can physically attach to phytoplankton cells. To explore the biogeochemical impacts of such associations, we performed transcriptomic analyses of bacterial-dinoflagellate and bacterial-diatom model systems consisting of the Roseobacter clade members Roseovarius nubinhibens ISM and Ruegeria pomeroyi DSS-3 with the phototrophic dinoflagellate Alexandrium tamarense CCMP1771 and cosmopolitan diatom Thalassiosira pseudonana CCMP1335. Both systems were designed such that the bacterium relied on its phytoplankter partner for reduced carbon and nitrogen, while the phytoplankter relied on the bacterium for a source of cobalamin. Using RNA-Seq methodology to investigate differences in gene expression in co-cultures versus monocultures, we discovered several sulfonium and sulfonate compounds that appear to act as major currencies in the interactions between bacteria and phytoplankton. These unexpected metabolites are likely cycled over short time scales at sub- micron distances, and may be important but cryptic links in both carbon and sulfur transformations in the ocean.

239 MONDAY 9 SEPTEMBER 2013, 17:30 PS-4. Bacterial life strategies in relation to carbon flow to higher trophic levels

PS-4.07. GENOMIC AND PROTEOMIC INSIGHTS OF ENHANCED GROWTH OF A SEA-ICE PSYCHROPHILE PSYCHROFLEXUS TORQUIS BY PROTEORHODOPSIN POHOTOROPHY DURING SALINITY STRESS

Shi Feng, University of Tasmania (Australia) Coauthors: Powll S, Wilson R, Bowman J

The discovery of Proteorhodopsin challenged the conventional view that chlorophyll a is the only important light capturing pigment in ocean surface waters. Thus understand the role of proteorhodopsin may renew our opinion of matter and energy transfer through the microbial loop. The current hypothesis is that proteorhodopsin could provide an adaptive advantage to the bacteria under oligotrophic conditions. To date all studies have focused on explaining the physiological role of proteorhodopsin that might affect bacterial growth during periods of low- nutrient or carbon limited conditions. However, since proteorhodopsins are widespread in natural environments and these environments may have many other stressful conditions in which proteorhodopsin may be advantageous. We hypothesize that proteorhodopsin may be an important provider of light derived energy under stress conditions that are associated with a specific econiche in a nutrient independent manner. Here we report for the first time that light stimulated growth of a sea-ice isolates Psychroflexus torquis occurs under conditions of salinity stress rather than nutrient limitation and that elevated salinity is related to increased growth yields. Genome analysis revealed that a cluster of putative ice-binding/adhesion genes are next to proteorhodopsin gene and its cognate carotenoid monoogygenase, thus proteorhodopsin is suspected to have a role aiding sea-ice inhabitation and persistence in this particular strain. It as well showed the genome harbors quite a few light sensing bacteriophytochrome genes compare to another Psychroflexus strain which also produce proteorhodopsin gene but does not response to light. We also used gel-free 1D LC/MS to obtain whole proteome data which suggested that proteorhodopsin levels and associated proton pumping activity, and proteorhodopsin abundance in P. torquis also is post-transcriptionally regulated by both light and salinity and thus could represent an adaptation to its sea-ice habitat. Our findings extend the existing paradigm that light provides an energy source for under stress conditions other than nutrient limitation.

240 MONDAY 9 SEPTEMBER 2013, 17:30 PS-4. Bacterial life strategies in relation to carbon flow to higher trophic levels

PS-4.08. EXPLORING BOTTOM-UP AND TOP-DOWN REGULATION OF FRESHWATER AAP BACTERIA IN A LARGE-SCALE LAKE MESOCOSM EXPERIMENT

Carolina Garcia, Universite du Quebec a Montreal (Canada) Coauthors: del Giorgio P

Aerobic anoxygenic phototrophic (AAP) bacteria are photoheterotrophic prokaryotes able to use light as a secondary energy source to the consuming of organic matter. During the last decade there has been much progress in our understanding of the abundance and distribution of AAP across marine and freshwater environments. The metabolic flexibility, fast growth and cosmopolitan nature of AAP bacteria, suggest that this light harvesting capacity may have a significant ecological advantage and therefore an effect on organic carbon fluxes and food web dynamics. However, the relative abundance and importance of AAP bacteria to the flow of energy and carbon in aquatic systems are still controversial because AAP generally show abundances seldom higher than 10% and we ignore the biological and the abiotic factors that influence AAP bacterial abundance and activity, particularly in freshwaters. Here we present the results of a lake mesocosm experiment designed to explore the bottom-up (DOC and nutrients), and top-down (grazing and viral infection) factors as regulators of the distribution and activity of freshwater AAP bacteria. The experiment was carried out in oligo-mesotrophic lake Cromwell, in the temperate region of Québec, where we filled 5000 L (6 m deep) mesocosms. Triplicate mesocosms were supplemented either with terrestrially derived DOC, nutrients (N and P), or DOC + nutrients. We followed the evolution of these mesocosms over the course of 45 days, in particular in terms of total bacterial and AAP abundance and biomass, and total bacterial and AAP growth. We further carried out grazer and virus-free incubation experiments at various time points, to assess the potential top-down control of AAP abundance. Preliminary results suggest strong shifts in the absolute and relative abundance of AAP, as well as in AAP growth rate, as a response to varying resources top-down control.

241 MONDAY 9 SEPTEMBER 2013, 17:30 PS-4. Bacterial life strategies in relation to carbon flow to higher trophic levels

PS-4.09. ISOLATION OF POTENTIAL BIOSURFACTANT PRODUCERS FROM THE SEA-PEN PTEROEIDES SPINOSUM (ELLIS, 1794)

Marco Graziano, University of Messina (Italy) Coauthors: Rizzo C, Michaud L, Porporato EMD, De Domenico E, Lo Giudice A

Biosurfactants (BSs) are amphipatic compounds produced by microorganisms, which act at interface between substances of different polarity. The aim of this study was the isolation of BS producer bacteria from the sea-pen Pteroeides spinosum (Ellis, 1794) (Anthozoa: Octocorallia). Specimens of Pteroides spinosum were aseptically collected from Giardini Naxos (Messina), and used for bacteria isolation. Moreover, pennatulids homogenates were used to inoculate 250 ml of mineral medium ONR7a supplemented with crude oil (1%, v/v) as a sole carbon source. A total of 22 and 96 strains were isolated from natural samples and enrichment cultures, respectively. The use of the DCPIP assay (2, 6-dichlorophenol-indophenol) allowed selecting 61 and 11 isolates from enrichment cultures and natural samples, respectively, for further analyses. Selected isolates were screened for BS production in mineral medium ONR7a at 28°C, by performing standard tests at intervals of 48 hours: optical density, emulsification, E24 index detection, blood agar assay, C-TAB assay, surface tension measurement, penetration assay. Positive strains were taxonomically identified by 16S rRNA gene sequencing. The most promising isolates were additionally used for an optimization experiment, during which influence of temperature (15°C, 25°C, 30°C), carbon source (tetradecane, crude oil, diesel oil) and salinity (0%, 3%, 7%) on BS production was investigated. The BS production screening allowed to select five potential BS producers, among which four were isolated from enrichment cultures (PBE181, PBE190, PBE209, PBE178), and one from natural samples (PBN295). They were affiliated to the genera Vibrio (isolate PBN295) and Brevibacterium (isolates PBE181, PBE190, PBE209, PBE178). Different kinetics of production was observed in relation to the taxonomical affiliation. Obtained data suggest the possibility to use biological matrices, poorly investigated for this purpose, for the isolation of BS producer strains.

242 MONDAY 9 SEPTEMBER 2013, 17:30 PS-4. Bacterial life strategies in relation to carbon flow to higher trophic levels

PS-4.10. THE ROLE OF DIFFERENTLY SIZED BACTERIA FROM THE GENUS LIMNOHABITANS IN CARBON TRANSFER TO HETEROTROPHIC FLAGELLATES

Vesna Grujcić, Biology Centre AS CR, Hydrobiological Institute, Ceske Budejovice (Czech Republic) Coauthors: Kasalický V, Matousu A, Simek K

Different freshwater bacteria might represent markedly different food quality sources for their major grazers, heterotrophic nanoflagellates (HNF). It raises an important question: Which species or morphotypes of closely related strains represent an important link in carbon flow to higher trophic levels? Bacteria of the genus Limnohabitans are abundant in various freshwater habitats and they display high growth rates, with a tight relationship to algal-derived substrates. Their growth potential is counterbalanced by a marked vulnerability to HNF grazing, which makes this bacterial group an invaluable model for testing of its role in carbon flow to higher trophic levels. We conducted experiments with natural HNF communities fed by 3 Limnohabitans strains of moderate to large cell sizes during late April and late May (2012) in two distinct habitats: the Římov reservoir and a sandpit lake Cep (both South Bohemia). Plankton samples were pre-filtrated (5 µm) to release natural HNF communities from zooplankton grazing. The 5-µm filtrates from both study sites were adjusted with 0.2-µm filtered water from their home habitats to set the starting HNF abundance to ~3, 000 ml-1.Then experimental treatments were amended separately with Limnohabitans strains of different size and morphology: L. planktonicus (rod-shaped, MCV = 0.135 µm3), T6-5 (thin curved rod, 0.128 µm3) and 2KL-3 (large solenoid, 0.204 µm3). Since they differ in cell volumes, their initial cell numbers added were set to yield the same initial biovolume for all 3 strains, giving ~20-fold the natural background bacterial biovolume present in non- amended control treatment. We determined prey-specific HNF growth rate, growth efficiency, length of HNF lag-phase and prey decay rates. All Limnohabitans strains supported HNF growth (DT = 8-14 h), however, in highly prey-specific fashions. For instance, additions of moderately large strains, namely of T6-5, but also of L. planktonicus, yielded mostly rapid HNF growth (DT = 8-10 h) with shorter lag phase. The larger cell size of 2KL-3 and its curved morphology make this prey partially protected against grazing by small HNF, resulting in lower HNF growth and longer lag phase. Notably, the same prey items induced significantly shorter lag phase of HNF growth in Římov than in Cep. It likely reflects generally smaller cells sizes of HNF found in Cep, where we assume a longer “adaptation time” to the large prey size offered via profound shifts in the HNF community.

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PS-4.11. TEMPERATURE DEPENDENCE OF PROKARYOTIC AUTOTROPHY IN THE MESO- AND BATHYPELAGIC ATLANTIC OCEAN

Roberta L. Hansman, University of Vienna (Austria) Coauthors: Debeljak P, Herndl GJ

Chemoautotrophy in the meso- and bathypelagic ocean has recently been identified as a significant of prokaryotes comparable to the magnitude of heterotrophic prokaryotic metabolism. While some studies have implicated the oxidation of ammonia by members of Thaumarchaeota as fueling dissolved inorganic carbon (DIC) fixation, the extent and potential of in situ energy sources for chemoautotrophy in the dark ocean have not been fully identified and quantified. Seawater collected in the meso- and bathypelagic eastern Atlantic Ocean and incubated at 20˚C exhibited DIC fixation rates up to 500 times greater than rates measured at in situ temperatures. These high rates of autotrophy are not accompanied by an increase in prokaryotic abundance, indicating a probable gene expression response by organisms present in situ. As these incubations were amended solely with 14C-labeled bicarbonate, it appears there are potential energy sources available in the dark ocean supporting high levels of chemoautotrophy that are not, or not efficiently, utilized at ambient temperatures. In incubation experiments, the temperature dependence of the DIC fixation as well as the accompanying changes in microbial community composition were determined in combination with a metagenomic approach to further constrain the chemoautotrophic potential of the deep ocean.

244 MONDAY 9 SEPTEMBER 2013, 17:30 PS-4. Bacterial life strategies in relation to carbon flow to higher trophic levels

PS-4.12. THE INFLUENCE OF LIGHT ON CARBON UTILIZATION IN AEROBIC ANOXYGENIC PHOTOTROPH

Dzmitry Hauruseu, Institute of Microbiology, the Czech Academy of Sciences, Trebon (Czech Republic) Coauthors: Koblizek M

Aerobic anoxygenic phototrophs are prokaryotes which harvest light energy using bacteriochlorophyll-containing reaction centres. In this study we investigated the efficiency of their carbon metabolism in carbon-limited chemostat cultures. Erythrobacter sp. NAP1 and Roseobacter sp. COL2P were grown in carbon limited chemostat regime on defined carbon sources (glutamate, pyruvate, acetate, fumarate, leucine, glucose) and illuminated with different light intensities. When grown in a light-dark cycle these bacteria accumulated 25 - 110% more biomass in terms of carbon when compared to the cultures grown in the dark. Cultures grown on glutamate accumulated most of the biomass at 150 μmols m-2s-1, but were inhibited at higher light intensities. In the case of pyruvate we did not find any inhibition of growth by high irradiance. In addition, the incorporation of radiolabeled bicarbonate was studied in cultures of Erythrobacter sp. NAP1. In the culture grown on pyruvate there was a strong stimulation of carbon incorporation by light. In contrast, glutamate grown cultures showed almost no effect of light bicarbonate incorporation. The enhanced efficiency of aerobic anoxygenic phototrophs in carbon utilization might be an important competitive advantage when growing under carbon limited conditions.

245 MONDAY 9 SEPTEMBER 2013, 17:30 PS-4. Bacterial life strategies in relation to carbon flow to higher trophic levels

PS-4.13. MONOMERIC SUBSTRATE UPTAKE BY DOMINANT FRESHWATER BACTERIAL CLADES/GROUPS

Maria Teresa Perez, University of Innsbruck (Austria) Coauthors: Sommaruga R

Here, we present results on monomeric substrate uptake by dominant freshwater bacterial clades/groups in two alpine lakes. Substrate uptake patterns were examined by means of microautoradiography (MAR) combined with catalyzed reporter deposition fluorescent in situ hybridization (CARD-FISH). The monomers chosen represented four different chemical species involved in the biochemical cycles of carbon (C), nitrogen (N) and phosphorus (P). Four large taxonomic groups were found in the lakes sampled with Actinobacteria and Betaproteobacteria dominating the bacterial assemblage. All bacterial groups examined were able to incorporate amino acids, adenosine triphosphate (ATP) and glucose, though to a different extend. On the contrary, acetate was only taken up by ~10 % of bacterial cells and acetate uptake was not detected in Cytophaga-like bacteria in the lakes we examined. Our results point out to a differential uptake of monomers by specific bacterial groups that could ultimately influence the flow of C, N, P to higher tropic levels.

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PS-4.14. DEEP-SEA PROKARYOTIC HETEROTROPHIC ACTIVITY IN THE BIOGEOGRAPHICAL PROVINCES OF THE WORLD’S OCEAN

Thomas Reinthaler, Department of Limnology & Oceanography, University of Vienna (Austria) Coauthors: Yokokawa T, Nagata T, Herndl GJ

Prokaryotic heterotrophic production using radiolabeled leucine is one of the most sensitive methods assessing prokaryotic activity in the ocean and is thus useful to evaluate the impact of heterotrophic microbes on the microbial carbon pump. Here we aimed at testing the hypothesis that regional processes in the surface ocean constrain dark ocean heterotrophic activity. We divided the ocean into biogeographical provinces that provide a framework to spatially aggregate data and compare biogeochemical processes over broad regions, and analyzed a global set of about 2600 prokaryotic production measurements from a depth range of 200 – 4000 m. The prokaryotic activity decreased less with depth in the high latitude North Atlantic provinces than in the oligotrophic subtropical gyre regions. Our results generally suggest that dark ocean prokaryotic activity in the more productive North Atlantic provinces is primarily influenced by sinking organic matter derived from the surface layers. In contrast, buoyant or slowly sinking particles and dissolved organic matter partly originating from the source water regions might be relatively more important in the oligotrophic gyre regions than in the northern North Atlantic. Similar regional differences in dark ocean prokaryotic activity were also apparent in available Pacific and Arabian Sea datasets, indicating a common set of processes influencing prokaryotic activity in distinct oceanic provinces.

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PS-4.15. SUBSTRATE SPECIALIZATION LIFE STRATEGIES OF FRESHWATER BACTERIOPLANKTON

Monica Ricao Canelhas, Limnology/Dept of Ecology and Genetics Evolutionary Biology Centre, Uppsala (Sweden) Coauthors: Bertilsson S

Generalist and specialist metabolic strategies of bacteria determine their ability to adapt to environmental niches defined by the availability of substrates. Substrate generalists are usually considered better adaptors and compete successfully in a wide range of environments, while substrate specialist are rare in all but the a few systems where their specific metabolic requirements are met. Free amino acids is are readily consumed by heterotrophic bacteria and because of their lability, it has been argued that there is no phylogenetic signal in amino acid consumption; e.g. all bacteria take up all amino acids. However, recent studies have shown some indication of phylogenetic groups that preferentially use specific amino acids (Cottrell & Kirchman, 2000; Salcher, 2010). We hypothesize that there are defined phylogenetical groups of bacteria adapted to preferentially use different amino acids for their metabolic needs while others have a wider substrate range. Sequential enrichment cultures fed with different individual amino acids were used to evolve different bacterioplankton communities. We subsequently performed a reciprocal transplant incubation to assess if substrate preferences were maintained. Bacterial growth was assessed with flow cytometry and amino acid utilization was determined with fluorescence quantification of opa-derivatives. Our experiments indicate some degree of substrate specialization in the evolved communities, but also point to differences between the specific amino acids tested and specific amino acid combinations. This type of substrate specialization may be important traits governing the ecology and biogeochemical roles of freshwater bacteria.

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PS-4.16. SEASONAL BACTERIA-DRIVEN ORGANIC MATTER EXPORT ALONG A CROSS-SHELF EUTROPHICATION GRADIENT IN SOUTH SULAWESI, INDONESIA

Hauke Schwieder, Leibniz Center for Tropical Marine Ecology (ZMT) GmbH, Bremen (Germany) Coauthors: Gärdes A

By triggering the production of transparent exoploymer particles (TEP) by phytoplankton, bacteria can be key players in the export of organic matter to the through aggregates. But although the effects of increased inorganic and organic nutrients on microbial community structures have been studied previously, their role in the bacterial contribution to particle formation, especially in coastal tropical ecosystems, remains poorly understood. We sampled along a cross-shelf gradient in the Spermonde Archipelago off Makassar, South Sulawesi, Indonesia in October 2012 (dry season) and in February 2013 (rainy season). This area offers ideal conditions to in-situ study anthropogenic impacts on microbial communities along a well-studied cross-shelf eutrophication gradient. Chlorophyll a, as a good indicator for inorganic nutrient loading, dissolved and particulate organic matter (DOM and POM, respectively) were investigated using fluorometric and spectro-photometric techniques. Changes in the microbial community along the gradient were elucidated using Terminal Restriction Fragment Length Polymorphism (T- RFLP). Water quality parameters showed strongly elevated concentrations close to the city of Makassar and decreased along the investigated cross-shelf gradient. We detected distinct changes in microbial communities from less to heavily influenced sites along the gradient. Heterotrophic bacteria were the dominant group wherever we found DOM, POM and chlorophyll a in high concentrations. Those changes were accompanied by an increased formation of TEP, confirming previous studies highlighting the possible importance of bacteria in the generation of those gel- like macromolecules. Thus, this study, as one of the first to combine quantitative and qualitative molecular techniques, provides a first insight into how changes in organic matter availability not only have important implications for the cycling of organic matter through an increased bacteria- driven export. In addition a closer investigation of the microbial communities on the sinking particles will provide complimentary insights into the transfer of potential coral pathogens in high abundances from the water column to the benthic coral reef communities.

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PS-4.17. LINKING MICROBIAL ENZYMATIC ACTIVITY TO CO2 OUTGASSING FROM FLOODPLAIN BACKWATERS UNDER VARIABLE HYDROLOGICAL CONNECTIVITY.

Anna Sieczko, University of Vienna (Austria) Coauthors: Meisterl K, Peduzzi P

River-floodplain systems play an important role in organic matter cycling and carbon mineralization. Despite numerous studies on carbon processing and dissolved CO2 concentrations in inland waters, respiration within fringing floodplains and its role in carbon flux (CO2) to the atmosphere remains largely unknown. Typically, floodplains are characterized by variable hydrological connectivity, which alters numerous exchange processes between backwaters and the main river. For this study, sampling locations in the Danube river-floodplain near Vienna (Austria) were chosen in a way that they represent a gradient of connectivity with the main river. Here we demonstrated the importance of variable hydrological connectivity for CO2 outgassing in different subsystems of the river-floodplain. Our results revealed that floodplain backwaters are supersaturated with CO2, which indicates that they serve as CO2 sources. However, the magnitude of the CO2 outgassing depends on the degree of connectivity. The semi-isolated, mostly disconnected floodplain lakes displayed 3 times higher excess partial pressure values (Ep) than locations frequently connected to the main river. Additionally, we applied measurements of extracellular enzymatic activity, both free-living and associated with particles, in order to examine DOM utilization patterns by microorganisms. With this approach we attempted to understand the partitioning of DOM-substrate, either for bacterial growth or respiration. Our results indicate that elevated activity of C-acquiring enzymes was positively linked to Ep. This implies that, at least in hydrological dynamic stations, increased CO2 outgassing is largely driven by degradation of carbohydrates. Our study stresses the significance of hydrological connectivity within a river- floodplain system for microbial processing of DOM. This will be of consequence for overall CO2 flux, when artificially severing the connection between the main river and its floodplain.

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PS-4.18. SUCCESS OF LIFE STRATEGIES IN MARINE MICROBIAL FOOD WEB MODELS AND THEIR INFLUENCE ON ECOSYSTEM FUNCTIONING

Selina Vage, University of Bergen (Norway) Coauthors: Thingstad TF, Castellani M, Storesund JE, Giske J

Using simplified food web models, we address the question when particular life strategies may be particularly successful in pelagic microbial communities. Specifically, we present a bacteria-phage model with trade-off between nutrient competition and viral defense. Showing that the amount of prokaryote production being shunted down into the viral loop depends on the cost of resistance and maximum bacterial growth rates, this model links trade-off and strategy choice to ecosystem functioning and biogeochemical cycling. Using a mixotrophic food web model, we also show that the success of different cell sizes and foraging mode strategies (ranging from pure auto- to pure heterotrophy) depends on trade-offs between maximum auto- and heterotrophic uptake rates, optimal predator-to-prey size ratios, and total system nutrient contents. As foraging mode and cell size critically influence carbon transfer between trophic levels, this model may help understand relevant control mechanisms for the cycling of carbon in the pelagic ocean.

251 MONDAY 9 SEPTEMBER 2013, 17:30 PS-4. Bacterial life strategies in relation to carbon flow to higher trophic levels

PS-4.19. HETEROTROPHIC ACTIVITY OF ARCHAEA AND BACTERIA IN THE WATER COLUMN OF THE JAPAN TRENCH, WESTERN PACIFIC

Taichi Yokokawa, Center for Marine Environmental Studies, Ehime University, Matsuyama (Japan) Coauthors: Yanagawa K, Nunoura T

Archaea are ubiquitously present in all the major oceanic basins and are accounting for about one third of total prokaryotic (Bacteria and Archaea) abundance in the waters below the euphotic zone. Although Archaea are abundant in deep waters, little is known about their metabolic rates, and their biogeochemical role in the ocean. In this study, we determined the contributions of the Archaea and Bacteria to total leucine incorporation (as an indicator of heterotrophic activity) throughout the water column of the Japan Trench, western Pacific. The bacterial inhibitor erythromycin and the archaeal inhibitor diphtheria toxin were used to determine the contribution of Bacteria and Archaea, respectively, to total leucine incorporation. Depth profile of total leucine incorporation rates showed exponential depth-dependent decrease from 126 ± 12 pmol L-1d-1 in the surface layer (0 - 100 m depth), to 0.59 ± 0.34 pmol L-1d-1 in bathy- and abyssopelagic layers (1500 - 7000 m depth). The contribution of bacteria to leucine incorporation rate was high (91 ± 9%) in the surface and mesopelagic layers, and kept in constant rate (52 ± 13%) in the bathy- and abyssopelagic layers. In contrast, the contribution of Archaea to the incorporation tare was low (24 ± 10%) in the surface layer, and kept in relatively high constant rate (41 ± 29%) below the mesopelagic layer. Our results show that heterotrophic activity of Archaea was comparable to the activity of Bacteria below the mesopelagic layer of the Japan Trench.

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PS-4.20. ASSAY OF THE SELECTIVITY OF PREDATION OVER DIFFERENT MICROBIAL POPULATIONS CARRIED OUT BY

Luca Zoccarato, Department of Life Science, University of Trieste (Italy) Coauthors: Antonioli M, Pallavicini A, Fonda Umani S

Oligotrophic environments intrigue because of the key role of the bacteria and their smallest predators in presence of low nutrient concentrations. The grazing activity of small protists shapes the microbial community and can change its abundances as well as produces shifts in its composition with crucial ecological implications within the marine food web. During the 2011 OBAMA cruise (from March 24 to April 6), we investigated four sampling sites of two different basins: O_36, O_37B (South Adriatic Sea), MS_03A, CF_16 (Ionian Sea). In order to assess that there is a predation and moreover that it is also selective against different bacteria populations we set up a fingerprinting experiment based on the Automated Ribosomal Intergenic Spacer Analysis (ARISA). For different areas we collect three kind of samples: a T0 in which the community dynamics are taken as they are immediately after sampling, a T24 that include an incubations of 24 hours at in situ conditions and a T24<3μm that in addition to the incubation, it is free from protists larger than 3μm. DNA extraction, PCR amplifications and capillary electrophoresis on a sequencer machine, were made later at the home laboratory. OTUs’ compositions in the Adriatic basin result richer compared to that of the Ionian one and also the equitability values are slightly higher. Cluster analysis conducted via UPGMA algorithm and based on Whittaker index shows that community profiles belonging to the same sampling area result effectively less dissimilar between them than to communities belonging to different sampling areas. These support the thesis that bacterial community composition clustered according to the water masses. Moreover, CF16 and MS03A share the most abundant OTUs as well as O36 and O_37B and from a preliminary analysis it seems not belonging to the same taxa. Comparing the outputs of the two different incubations it appears evident as in the absence of larger predators and thus likely of intra-predation within the protists, the bacterial communities are simplified with major OTUs that become even more abundant and the minor OTUs that decrease in abundance. The presence of the whole nanopredator community led to the rise of the intermediate abundance OTUs.

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PS-5.01. CAN THE CONCEPT OF BE APPLIED TO BIVALVE MOLLUSC? FIRST INVESTIGATION AT THE LARVAL STAGE

Katia Asmani, IFREMER, Brest (France) Coauthors: Petton B, Le Grand J, Robert R, Nicolas JL

The concept of holobiont has been developped in mammals especially in human and it has been progressively extended to other animals. The organisms are no longer seen as isolated individuals without their microbiota. However, except insect and cnidarian models there is no knowleges about invertebrates bacterial communities. In order to test this hypothesis, we studied the microbiota of bivalve larvae cultured in different conditions. In two experiments aiming to adapt the recirculating aquaculture system (RAS) for bivalve larvae, the bacterial populations were followed in various compartments (seawater, larvae). Their identification was carried out by sequencing the 16 rRNA gene. A metagenomic approach was also performed in order to have a more comprehensive view of diversity. RAS in comparaison with FTS (Flow Through System) tended to decrease the bacterial load in the larvae even with high larval density. In addition RAS did not promote the establishment of Vibrio populations in the larvae but a diversified microbiota. It also appears that the microflora of the larvae established in the early days and was maintained during the rearing independently of the surrounding water. Therefore, there is a real environmental advantage for the first bacteria in contact with the larvae. These first results seem to confirm the hypothesis that a microbota is intimately associated with the host. An experiment at postlarval stages should be able to conclude on the stability of microbiota and to prove if the concept of holobiont can be applied to the mollusc bivalve.

254 TUESDAY 10 SEPTEMBER 2013, 17:30 PS-5. Giving and getting: lifestyles of attached and symbiotic microbes

PS-5.02. TRANSCRIPTIONAL PROFILING OF PROCHLORON AND ACARYOCHLORIS MARINA IN HOSPITE

Lars Behrendt L, University of Copenhagen (Denmark) Coauthors: Larkum AWD, Hansen LH, Sorensen SJ, Kühl M

The (sub) tropical didemnid ascidian Lissoclinum patella harbors two enigmatic cyanobacteria, (1) the chlorophyll (Chl) b-containing prochlorophyte Prochloron spp.which resides as a symbiont within the cloacal cavity of the ascidian, (2) the Chl d-containing cyanobacterium Acaryochloris marina, which resides in a biofilm on the underside of L. patella, where it utilizes near-infrared light for oxygenic photosynthesis. Both habitats are characterized by steep gradients of O2 and pH that change rapidly in response to irradiance. Here we used transcriptional profiling (RNAseq) of Prochloron and A. marina to gain first insights to their in situ gene expression during light or darkness. Gene expression analysis revealed a concerted up-regulation of photosystem and stress related genes during midday and a significant down-regulation of genes involved with CO2 fixing pathways during the same time in both Prochloron and A. marina, possibly explainable by the observed high O2 levels and their interaction with RuBisCO and the pathway. Astoundingly, Prochloron was found to constitutively express three genes associated with the production of patellamides, cyclic peptides currently in pharmaceutical trials due to their cytotoxicity, with yet unknown ecological significance. A. marina was found to actively upregulate the expression of a ferredoxin-assembly gene (SufD) which corroborates earlier findings of iron starvation in A. marina and complements the abovementioned findings for Prochloron. The results are discussed based on our current knowledge of A. marina, Prochloron and their respective microenvironment.

255 TUESDAY 10 SEPTEMBER 2013, 17:30 PS-5. Giving and getting: lifestyles of attached and symbiotic microbes

PS-5.03. ALGAL-MICROBE INTERACTIONS: UNDERSTANDING THE MOLECULAR MECHANISMS THAT INFLUENCE SYMBIOSIS BETWEEN ALGAE AND BACTERIA

Vaibhav Bhardwaj, Magdalene College, Cambridge (UK)

Algae offer a unique opportunity for producing low cost biofuel while at the same time using less land and water when compared to corn or sugarcane. Nonetheless there are several challenges that need to be overcome before this process becomes commercially viable. One of the challenges of cultivating algae on a large scale is protecting the crop from invasive microorganisms. Kazamia et al. (2012) propose creating a synthetic ecosystem by populating algal ponds or photobioreactors with known symbiotic bacteria that act in concert with the surroundings to promote algal growth and minimise risk of infection. This is achieved by selecting symbiotic microbes to occupy niches that parasitic microbes may have tried to enter. Our lab developed an alga-microbe system to study symbiosis using Lobomonas rostrata (alga) and Mesorhizobium loti (bacteria). The symbiosis is dependent on the bacteria providing the algae with vitamin B12 and in turn the algae providing the bacteria with a fixed carbon source. I am investigating whether genes involved in Vitamin B12 synthesis are expressed at higher levels in the bacteria when the bacteria are grown in co-culture with Lobomonas compared to mono-culture. Additionally I also performed in silico studies identifying putative genes in Chlamydomonas reinhardtii that may be involved in algae-microbe interactions. Collectively this work seeks to improve our understanding of alga- microbe interactions.

256 TUESDAY 10 SEPTEMBER 2013, 17:30 PS-5. Giving and getting: lifestyles of attached and symbiotic microbes

PS-5.04. SPATIO-TEMPORAL VARIATION OF THE MARINE BIOFILM COMMUNITIES COLONIZING ANTIFOULING COATINGS IN THE MEDITERRANEAN SEA VS THE ATLANTIC OCEAN

Jean-François Briand, MAPIEM - Toulon University, La Garde (France) Coauthors: Urvois F, Gregori G, Réhel K, Bouchez A, Garnier C, Barani A, Le Berre B, LePoupon C, Bressy C, Blache Y

When immersed in sea water, any substrate would be rapidly colonized by micro and then macroorganisms. This complex and sequential natural process called biofouling induces economic and ecological prejudices, especially talking about ship hulls or aquaculture nets. Antifouling (AF) coatings are required to prevent the colonisation of ship hulls. Biocidal coatings include several active molecules that aim to target the diversity of potential colonizers that could come across in marine environment. Generally several biocides are associated without clear idea of the effect of each one. In this study, we intend to characterize the individual effect of three commercial biocides (Copper pyrithione, Zinc pyrithione and Zineb®) on biofilm communities that represent the first step of colonisation of immersed artificial surfaces. Each biocide was dispersed in a (meth)acrylic-based matrix (Neocryl B725®). Coatings composed of the polymer matrix alone together with a Poly(vinyl chloride) (PVC) reference surface were also immersed in triplicates as controls. Coated panels and controls were immersed in sea water for one month in order to get mature biofilms beyond pioneer stages, at each season (Winter, Spring, Summer and Autumn), in two temperate but contrasted French coastal sites, Toulon Bay (North-Western Mediterranean Sea) and Lorient harbour (Atlantic Ocean). Water quality including trace metals (Cd, Co, Cu, Ni, Pb, Zn) concentrations was monitored during the immersion periods. Microbial communities were analysed through their complexity using complementary tools: PCR-DGGE, pyrosequencing and flow cytometry for prokaryotes, microscopy for microphytobentic populations. Preliminary results showed that copper pyrithione was the most efficient biocide. Although they are both significant, immersion site effect seems to be more important than the seasonal one on the community structures. The current analysis of the whole data will allow us to better define the specificity of the effect of each parameter (biocides, season, location) on the biofilm community.

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PS-5.05. LINKAGE BETWEEN COPEPODS AND BACTERIA IN THE NORTH ATLANTIC OCEAN

Daniele De Corte, University of Vienna (Austria) Coauthors: Lekunberri I, Garcia JA, Sintes E, Herndl GJ

Copepods and Bacteria are fundamental components of the pelagic food web and play key roles in the biogeochemical cycles. While their roles are well studied as separate entities, copepods and Bacteria might also live in close interaction which is much less studied, Copepods harbor a complex bacterial community consisting of resident and transient Bacteria, with often orders of magnitude higher abundance than in the surrounding water. The microhabitat provided by the copepods’ body is physico-chemically different from the surrounding water, highly enriched in dissolved and particulate organic matter and inorganic nutrients, with hypoxic and/or anoxic conditions that may favor the proliferation of specific bacterial groups. The aim of this study was to compare the free-living bacterial community composition of the surrounding seawater with that associated with copepods to better understand the linkage between zooplankton and Bacteria. We used 454 pyrosequencing of the 16S rRNA gene to uncover the bacterial diversity associated with these two different habitats. Significant differences were found between the bacterial communities associated with zooplankton vs. seawater, with Bacilli and Actinobacteria dominating the copepod-associated community and Alphaproteobacteria, Deltaproteobacteria and Synechococcophycideae dominating the free-living community. However, the presence of shared bacterial OTUs between the two distinct environments suggests the exchange or recruitment of bacterial organisms from seawater by the copepods. Taken together, our results indicate that zooplankton harbors a specific bacterial community different from that of the surrounding seawater.

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PS-5.06. OPTIMIZATION AND CHARACTERIZATION OF UREASE BY MARINE BACILLUS THURINGIENSIS N2

Nermeen EL-Sersy, National Institute of Oceanography and Fisheries, Enviromental division, Microbiology lab. Alexandria (Egypt) Coauthors: El-Sharouny EE, El-Bessoumy AA, Mothana AA, Olam ZA

The industrial application of urease is very expensive by modern techniques. With scientific progress, scientists try to produce a lot of urease enzymes from a vital source by modern techniques with least cost. Marine bacteria Bacillus thuringiensis N2 was selected as the experimental organism throughout this work which supported the highest enzyme activity (2.499 µmol/ml/min) after 72 h incubation. A Plackett-Burman statistical design was constructed to study the optimum environmental and physiological conditions that lead to maximum growth and enzyme productivity. It was revealed that the growth rate and enzyme production were markedly influenced with the medium composition. The Box-Behnken statistical design was performed to determine the most significant independent variables, at three different levels. The optimal response region of these factors was predicted using second order polynomial model fitted to the results obtained. Calculated optimum concentrations of yeast extract, 14 g/l, urea, 0.7 g/l, and Na2HPO4, 15 g/l, were predicted and attained a urease activity of 100 %. The crude extract was purified and some enzyme characteristics were studied.

259 TUESDAY 10 SEPTEMBER 2013, 17:30 PS-5. Giving and getting: lifestyles of attached and symbiotic microbes

PS-5.07. PHYLOGENETIC DIVERSITY AND ANTIMICROBIAL ACTIVITY OF MARINE BACTERIA ASSOCIATED WITH SPONGIONELLA GRACILIS

Amani ElAhwany, Faculty of Science, Alexandria University (Egypt) Coauthors: Ghozlan H, ElSharif H , Sabry S

Marine sponges are the most biodiverse and biologically productive of all marine ecosystems. Sponges harbor diverse and abundant prokaryotic communities. However, little is known about the diversity of sponge- associated microorganisms. We used molecular techniques to identify and compare the culturable bacterial assemblages associated with Spongionella gracilis collected from Mediterranian sea. The majority of bacterial community were members of Firmicutes and few of Gammaproteobacteria. Antimicrobial activity of the isolated bacterial strains was evaluated against four pathogenic bacteria, Candida albicans and two fungi. A relatively high proportion of microbial isolates displayed distinct antibacterial and anticandidal activities, suggesting that sponge associated bacteria may aid their host in protection against marine pathogens. The data suggest that marine bacteria associated with Spongionella gracilis offer promising candidates for production of novel antimicrobial compounds.

260 TUESDAY 10 SEPTEMBER 2013, 17:30 PS-5. Giving and getting: lifestyles of attached and symbiotic microbes

PS-5.08. SPATIAL VARIABILITY IN PARTICLE-ATTACHED AND FREE-LIVING BACTERIAL DIVERSITY IN SURFACE WATERS FROM THE MACKENSIE RIVER TO THE BEAUFORT SEA (CANDIAN ARCTIC)

Jean François Ghiglione, CNRS-Laboratoire d'Océanographie Microbienne LOMIC (France) Coauthors: Ortega-Retuerta E, Joux F, Jeffrey W

We explored the patterns of total and active bacterial community structure in a gradient covering surface waters from the Mackenzie River to the coastal Beaufort Sea in the Canadian Arctic Ocean. A special emphasis was made on the comparison of free-living (FL) vs. particle-attached (PA) communities, by coupling capillary electrophoresis-single strand conformation polymorphism (CE- SSCP) and pyrosequencing. We showed significant differences when comparing river, coast and open sea bacterial community structures. In contrast to the river and coastal waters, total (16S rDNA-based) and active (16S rRNA-based) communities in the open sea samples were not significantly different, suggesting that most present bacterial groups were equally active in this area. Additionally, we observed significant differences between PA and FL bacterial community structure in the open sea, but similar structure in the two fractions for coastal and river samples. Direct multivariate statistical analyses showed that total community structure was mainly driven by salinity (a proxy of dissolved organic carbon and chromophoric dissolved organic matter), suspended particles, amino acids and chlorophyll a. Furthermore, PA samples generally showed higher diversity (Shannon, Simpson and Chao indices) than FL samples. At the class level, Opitutae was most abundant in the PA fraction of the sea sample, followed by Flavobacteria and γ- proteobacteria, while the FL sea sample was dominated by α-proteobacteria. Finally, for the coast and river samples and both PA and FL fractions, β-proteobacteria, α-proteobacteria and Actinobacteria were dominant. These results highlight the coexistence of particle specialists and generalists and the role of particle quality in structuring bacterial communities in the area. These results may also serve as a basis to predict further changes in bacterial communities should climate change lead to further increases in river discharge and related particle loads.

261 TUESDAY 10 SEPTEMBER 2013, 17:30 PS-5. Giving and getting: lifestyles of attached and symbiotic microbes

PS-5.09. INFLUENCE OF MICROBIAL DMSP CATABOLISM ON BIOGENIC SULPHUR CYCLING IN A SYNTHETIC ALGAL-BACTERIAL MODEL SYSTEM

Angela Hatton, Scottish Association for Marine Science (Scotland) Coauthors: Shenoy D, Hart M, Green D

In 1988 Maureen Keller and co-workers demonstrated that a wide range of marine phytoplankton could produce dimethylsulphoniopropionate (DMSP), a compatible solute used to maintain their osmotic balance in seawater. More recent studies have shown that these phytoplankton groups can also produce dimethylsulphoxide (DMSO), although the reason has yet to be fully elucidated. However, to date none of these studies were conducted on confirmed axenic phytoplankton cultures. Recent studies have now shown that the majority of DMS is removed from seawater due to its bacterial oxidation to DMSO, and that many phytoplankton species will not functional optimally without the presence of associated bacteria, and this has raised the important question of whether the DMSO previously measured from phytoplankton cultures was purely algal in origin. This study aimed to investigate if associated bacteria could be responsible for the production of DMSO in algal cultures. Using a synthetic ecology approach we generated engineered cultures of the phytoplankton Scrippsiella trochoidea and bacterial associates with known DMSP catabolism in order to evaluate their influence on the potential production of DMSO. Results demonstrate conclusively, for the first time, that S. trochoidea can produce DMSO directly, but also show that the presence of certain bacterial species can significantly influence the amount of all biogenic sulfur compounds produced and released from marine phytoplankton.

262 TUESDAY 10 SEPTEMBER 2013, 17:30 PS-5. Giving and getting: lifestyles of attached and symbiotic microbes

PS-5.10. TRENDS IN THE INTESTINAL MICROBIOTA OF THE OLIVE FLOUNDER (PARALICHTHYS OLIVACEUS) DURING AGING

Tae Sung Jung TS, Gyeongsang National University (South Korea) Coauthors: Yu JE

The intestinal microbiota of fish consist of a very complex microbial ecosystem and are affected by physiological and environmental factors such as age, habitat and feed. They play important roles in developing host immune system, digesting food and deriving nutrition. Investigation on the intestinal microbiota of fish may reveal potential probiotics and pathogenic bacteria, and explain the characterization of the intestinal microbiota. In this study, we performed a metagenomic analysis of the intestinal microbiota of olive flounder (Paralichthys olivaceus) at different body weights by using next generation sequencing of 16S ribosomal RNA gene. The results indicated that the dominant phyla was Proteobacteria (99.7–99.8%) followed by Actinobacteria (0.22– 0.01%), Firmicutes (0.08–0.02%), and then Bacteriodetes (0.7–0.01%). The diversity of the dominant microbiota was relatively simple in small fish (bw <75 g, length <19 cm) but became more complex with increasing age, reaching a high degree of complexity in large fish (bw >490 g, length >34 cm). The dominant families in the small fish were Comamonadaceae (50.0%) and Vibrionaceae (39.7%) but 14.5% and 6.1% for the large fish, respectively. The dominant families in the medium fish (bw 100-160 g, length 23-26 cm) were Pseudomonadaceae (30.9%) followed by Vibrionaceae (24.2%), Moraxellaceae (18.4%), and then Enterobacteriaceae (11.9%). The large fish had the most diverse dominant microbiota, while almost half of the microbiota population belong under Shewanellaceae (52.5%). Moreover, we isolated 223 bacteria from flounder intestine and conducted cluster analysis and identification by using MALDI-Biotyper. This study provides new insight to the intestinal microbiota of olive flounder with different body weights.

263 TUESDAY 10 SEPTEMBER 2013, 17:30 PS-5. Giving and getting: lifestyles of attached and symbiotic microbes

PS-5.11. COMPARISON OF PARTICLE-ASSOCIATED AND FREE-LIVING ARCHAEAL COMMUNITIES IN THE WESTERN NORTH PACIFIC OCEAN

Ryo Kaneko, Atmosphere and Ocean Research Institute, University of Tokyo, Kashiwa (Japan) Coauthors: Uchimiya M, Fukuda H, Suzuki S, Ogawa H, Nagata T, Honda M, Hamasaki K

Although marine Archaea are ubiquitous and key mediators of global biogeochemical cycling in terms of metabolic activity and abundance, only few information about their lifestyle (free-living vs. particle-associated) in seawater column have been reported. Here, we report spatiotemporal change in community structures of particle-associated and free-living Archaea in the western North Pacific Ocean. Seawater samples were collected from epi-, meso- and bathypelagic depths (0, 300 and 2000 m) at the subarctic station K2 (47°N, 160°E) and the subtropical station S1 (30°N, 145°E) in winter (February, 2010) and summer (July, 2011) during cruises of R/V MIRAI. Two or four liters of seawater was serially filtered through 3.0-um and 0.22-um pore-size membranes, and stored at -80°C until an analysis in the laboratory. Genomic DNA was extracted aseptically from filter samples, and archaeal 16S rRNA gene fragments were amplified by PCR for the clone library analysis. The obtained 16S rRNA gene sequences were compared with sequences in the current database (NCBI) using BLASTn to determine phylogenetic relatedness. A total of 547 sequences of 16S rRNA gene were obtained from 24 clone libraries, from which two phylogenetic groups, Thaumarchaeota and Euryarchaeota, were formed. All sequences of Thaumarchaeota group were affiliated with the uncultured marine group I, and were found to occur in almost all seasons and depths. Sequences of Euryarchaeota group were related to the uncultured marine group II (MG2), group III (MG3) and unclassified clusters. The relative abundance of MG2 in the epipelagic zone showed remarkable changes from winter to summer at both sampling sites. Sequences of MG3 were prominently detected from some particle-associated fractions. The particle-associated communities and the free-living ones showed comparable species richness and shared many phylotypes (27-100%) with each other. Also, their species richness was higher in the meso- and bathypelagic depths than in the epipelagic depth. In this study, we have revealed that marine pelagic Archaea in the western North Pacific change their phylogenetic compositions by depth and seasons whereas they represent little difference between two lifestyles.

264 TUESDAY 10 SEPTEMBER 2013, 17:30 PS-5. Giving and getting: lifestyles of attached and symbiotic microbes

PS-5.12. MODELLING ALGAL-BACTERIAL INTERACTIONS PROVIDES EVIDENCE FOR DIRECT EXCHANGE OF FIXED CARBON FOR VITAMIN B12

Elena Kazamia, Department of Plant Sciences, University of Cambridge (UK) Coauthors: Grant MAA, Cicuta P, Smith AG

Approximately half of all microalgal species are auxotrophic for vitamin B12 (cobalamin) (Croft et al., 2005). However only bacteria are able to synthesise this complex metabolite (Warren et al., 2002), and so the ultimate source of cobalamin in aquatic communities is prokaryotic. How algae obtain vitamin B12 from bacteria in the natural environment is unknown. In the laboratory, we have shown a direct interaction between algae and heterotrophic bacteria (Croft et al., 2005; Kazamia et al., 2012). It was found that Mesorhizobium loti (MAFF303099), a vitamin B12 synthesising bacterium was able to support the growth of B12-dependent Lobomonas rostrata (a freshwater green alga belonging to the Volvocales) in return for fixed carbon. The two organisms form a stable equilibrium in terms of population numbers, which is maintained over many generations in semi-continuous culture, indicating a degree of regulation. However, addition of either vitamin B12 or a carbon source for the bacteria perturbs the equilibrium, demonstrating that the symbiosis is mutualistic and facultative. The interaction also demonstrated a degree of specificity, as other vitamin B12-synthesising bacteria were not as efficient at delivering the nutrient to the algae. It has been suggested previously that vitamin B12 is provided passively to algae by bacteria as a result of lysis following cell death (Droop, 2007). Passive exchange through lysis is also at the heart of the microbial loop hypothesis for the cycling of vitamin B12 in natural communities (Karl, 2002). I will present the results of mathematical modelling of the dynamics of L. rostrata in co-cultures with M. loti based on the physiological observations made in Kazamia et al. (2012). The growth model allowed to test whether exchange was due to active transfer of nutrients or mediated by the death and lysis of organisms. The results are consistent with the former, and have important potential implications for understanding of the evolution of vitamin B12 auxotrophy as well as the method of provision of this micronutrient in natural communities. Croft et al. (2005) Nature 438: 90-93; Warren et al. (2002) Natural Product Reports 19: 390–412; Kazamia et al. (2012) Environmental Microbiology 14(6): 1466-1476; Droop (2007) Journal of plankton research 29(2): 107-113; Karl (2002) TRENDS in microbiology 10(9): 410-418

265 TUESDAY 10 SEPTEMBER 2013, 17:30 PS-5. Giving and getting: lifestyles of attached and symbiotic microbes

PS-5.13. MARINE BACTERIA COLONIZING DIFFERENT JELLYFISH SPECIES

Kos Kramar M, National institute of Biology, Ljubljana (Slovenia) Coauthors: Turk V

Surfaces of marine eukaryotes were found to be a unique habitat for colonization by microorganisms and the bacterial communities associated with living surfaces showed great microbial diversity. Jellyfish recently became a more frequent and dominant part of marine ecosystems. Whether alive or decaying, they were found to stimulate bacterial growth and affect community composition. To what extent bacteria are attached to jelly surfaces and what is their possible role is unknown. We studied differences in the community composition of bacterial isolates between surrounding seawater and the umbrella surface and gastric cavity of four jellyfish species regularly observed in the Gulf of Trieste (Northern Adriatic): scyphomedusae Aurelia aurita, Cotylorhiza tuberculata, Chrysaora hysoscella and the hydromedusa Aequorea sp.. Each jellyfish was sampled separately with a net and washed three times with pre-filtered sea water (<0.22 um). To transfer bacteria from jellyfish surfaces to growth media, each jellyfish per test was touched to an agar plate to create a jelly imprint of “umbrella” associated bacteria. Additionally, the gastro vascular cavities of jellyfish were scraped with cotton swabs and inoculated on agar plates. A total of 380 colony forming units were isolated and prepared for comparative sequence analysis of 16S rRNA genes. Around 50% of the bacterial isolates obtained from jellyfish belonged to Gammaproteobacteria, dominated by Vibrionaceae and Pseudoalteromonadaceae. The rest of the bacterial isolates belonged to classes of Bacilli, Flavobacteria, Actinobacteria, Alphaproteobacteria and Betaproteobacteria. Bacteria attached to jellyfish tissue differed from those in the surrounding water. Some differences in diversity of bacterial isolates were also observed between jellyfish species but not between umbrella and gastro vascular cavities. The closest relatives to the 16S rRNA sequences of the bacterial colonies isolated from different parts of different jellyfish species were similar to those previously found to be attached to organic particles and to the communities of epibiotic bacteria reported on other .

266 TUESDAY 10 SEPTEMBER 2013, 17:30 PS-5. Giving and getting: lifestyles of attached and symbiotic microbes

PS-5.14. PRODUCTION AND OPTIMIZATION OF A BIOSURFACTANT FROM SOFT CORAL ASSOCIATED MARINE BACTERIUM

Mona El Sayed M Mabrouk, Botany Department, Damanhour University (Egypt) Coauthors: Youssif EM, Sabry SA

Marine microorganisms are of considerable current interest as a new and promising source of biologically natural products. Association between marine invertebrates and symbiotic bacteria are increasingly recognized as widespread and of biological importance. Coral reef ecosystems could be a largely unexplored source for marine microorganisms producing natural products. Biosurfactants are a structurally diverse group of extracellular surface-active compounds produced by bacteria, fungi and yeast. In the past two decades, biosurfactants have gained increasing attention due to their useful properties. The range of industrial applications of biosurfactants includes enhanced oil recovery, crude oil drilling, lubricants. The objective of this study was to isolate bacteria associated with the red sea soft coral Sarchophyton glaucum and screen for their capability to produce biosurfactant. The main criteria used for evaluation were hemolytic assay, emulsification of kerosen and the drop-collapse test. A potential biosurfactant producer was identified as Bacillus sp. EMS34. Among the tested carbon sources, sugar cane molasses proved to be the best. Plackett-Burman (PB) design with 11 variables was used to screen medium components that significantly influenced biosurfactant production. Molasses and FeSO4.7H2O were identified as the most important cultural factors which had a significant influence on surfactant biosynthesis. The emulsification index of the cell-free broth containing the biosurfactant remained very stable during exposure to a wide range of pHs (6-11) and temperatures (10-120°C). EMS34 biosurfactant was not precipitated or salted out in up to 20% sodium chloride solution. Current study shows that marine bacteria are good candidates for production of biosurfactant of biotechnological application.

267 TUESDAY 10 SEPTEMBER 2013, 17:30 PS-5. Giving and getting: lifestyles of attached and symbiotic microbes

PS-5.15. REDUCING MARINE BIOFILM FORMATION VIA SURFACE MODIFICATION: SUPPORTING SEAGRASS RESTORATION

James Paterson, Flinders University, Adelaide (Australia) Coauthors: Ogden S, Tanner EJ, Benkendorff K, Quinton SJ

The formation of biofilms on man-made surfaces is a common and problematic occurrence in the marine environment. In addition to man-made surfaces, biofilm formation can also appear on naturally occurring marine surfaces, such as sediment and rock substrates and plants. The commencement of a seagrass restoration project in South Australian waters has developed an approach to utilise natural hessian material to assist in seagrass recruitment. However, it is believed that biofilm formation may be a contributing factor in the degradation and longevity of this hessian material. In this context, we investigated the modification of hessian material using different coatings types to (i) reduce biofilm formation and (ii) extend hessian life. Our initial results, using flow cytometric analysis, indicated a reduction in virus like particle (VLP) and heterotrophic bacterial abundance between untreated and phenyltrimethoxysilane (PTMS) coated hessian. Furthermore, the cytometric sub-group formation of VLPs and heterotrophic bacteria exhibited distinct changes between coatings. The identification of bacteria within the formed biofilm on each hessian bag was also carried out using 16S pyrosequencing. These results highlighted marked changes in community composition between different coating types. This study provides an understanding on how the modification of hessian surfaces can alter the abundance and composition of the bacterial community formed in the associated biofilm, generating valuable information for further studies into antifouling in the marine environment.

268 TUESDAY 10 SEPTEMBER 2013, 17:30 PS-5. Giving and getting: lifestyles of attached and symbiotic microbes

PS-5.16. THE ROLE OF CELL COMMUNICATION IN THE ALGAL SYMBIONT DINOROSEOBACTER SHIBAE

Diana Patzelt, Helmholtz Centre For Infection Research, Braunschweig (Germany) Coauthors: Wang H, Buchholz I, Rohde M, Gröbe L, Pradella S, Neumann A, Schulz S, Heyber S, Münch K, Münch R, Jahn D, Wagner-Döbler I, Tomasch J

Dinoroseobacter shibae is a member of the Roseobacter clade abundant in marine environments and is found associated with dinoflagellates. Populations of D. shibae show an astonishing heterogeneity with respect to cell shape ranging from ovoid rods with a high variability in size to long filamentous cells. Furthermore not only the copy number of chromosomes differed between the distinct morphotypes, but also the type of cell division. As revealed by time-lapse microscopy, cells divide either by binary fission or budding from one or both cell poles. This phenotypic variability is lost when the quorum sensing (QS) system of D. shibae is silenced. QS is a form of cell- to-cell communication that involves production, excretion and detection of small diffusible signalling molecules called autoinducers (AI). In Gram-negative bacteria it is mediated through acylated homoserine lactones (AHLs). D. shibae utilises a complex communication system that involves three AHL synthases (luxI1-3). It produces novel AHLs with unsaturated C18 side chains. We constructed a ∆luxI1-knock-out strain completely lacking AHL biosynthesis. The mutant was uniform in morphology and divided by binary fission only. Transcriptome analysis revealed that genes responsible for cell cycle control were repressed in this strain, providing the link between quorum sensing and the observed phenotype. In addition, flagella biosynthesis and type IV secretion system (T4SS) were down-regulated. The wild-type phenotype and gene expression could be restored through addition of synthetic C18-AHLs. Moreover D. shibae specifically responds to foreign AHLs by up-regulation of selected traits. The strategy of using QS to induce phenotypic individualisation might be beneficial in unpredictably changing environments, e.g. during algal blooms when resource competition and grazing exert fluctuating selective pressures. A specific response towards foreign AHLs might provide D. shibae with the capacity for complex interspecies communication.

269 TUESDAY 10 SEPTEMBER 2013, 17:30 PS-5. Giving and getting: lifestyles of attached and symbiotic microbes

PS-5.17. SYMBIOTIC BACTERIA INCREASE THE POPULATION SIZE OF A FRESHWATER CRUSTACEAN, DAPHNIA MAGNA

Saranya Peerakietkhajorn S, Osaka University (Japan) Coauthors: Tsukada K, Kato Y, Matsuura T, Watanabe H

Daphnia magna, a freshwater filter-feeding zooplankton, is a key organism in freshwater ecological systems. In normal and healthy conditions, the populations are entirely parthenogenetic females with high ability to propagate, leading to the large population size that is necessary to play a role as a primary consumer in the ecological system. Abiotic factors such as temperature, photoperiod, quantity and quality of food are known to affect life-history traits of the female Daphnia. In contrast, roles of biotic factors, symbiotic bacteria, for the life history traits still remains unknown. To evaluate the contribution of the bacteria, we developed a method to make aposymbiotic daphnids and examine their life history traits, fecundity and longevity. Population size of aposymbiotic bacteria was 10 fold smaller than that of normal daphnids, suggesting that symbiotic bacteria have an essential role for fecundity. In contrast, we did not observe any significant differences in longevity between aposymbiotic and normal daphnids. In addition, by reinfecting the bacteria symbionts, the aposymbiotic daphnid gained its ability to produce offsprings. To further investigate symbiotic relationships between D. magna and bacteria, the bacterial community composition was observed. PCR amplification and identification of 16S rRNA genes of bacteria in daphnids showed that 50% of all sequences was Limnohabitans sp., one of Betaproteobacteria and the diversity of bacterial compositions was low. Our results suggest that a dominant bacterium, Limnohabitans sp. can recover fecundity in Daphnia. We for the first time have shown the influence of bacteria symbionts on the life-history traits of Daphnia. Aposymbiotic daphnid will be useful for understanding symbiotic relationships in animals and roles of bacteria in the freshwater ecosystem.

270 TUESDAY 10 SEPTEMBER 2013, 17:30 PS-5. Giving and getting: lifestyles of attached and symbiotic microbes

PS-5.18. IN SITU IDENTIFICATION OF NOVEL ENVIRONMENTAL CHLAMYDIAE IN A TYRRHENIAN COASTAL LAKE (LAGO DI PAOLA, ITALY)

Ilaria Pizzetti, Water Research Institute-National Research Council (IRSA-CNR) (Italy) Coauthors: Fuchs BM, Amann R, Fazi S

Until recently the bacterial phylum of Chlamydiae exclusively included one family of obligate intracellular bacteria, the Chlamydiaceae, which encompassed causative agents of severe diseases. In the 1990s, environmental chlamydiae were discovered as symbionts of free-living amoebae and other eukaryotic hosts. These findings showed an additional diversity of Chlamydiae in the environment. Moreover, recent studies suggest environmental chlamydiae as potential emerging pathogens. While monitoring Planctomycetes, we retrieved 20 almost full length 16S rRNA gene sequences affiliated with Chlamydiales from a lake at the Tyrrhenian coast of central Italy (Lago di Paola, Latium). Two main clusters were identified. The nine sequences within the tight cluster I shared ~ 98% identity, just like the six sequences of cluster II. The 16S rRNA sequence identity between the two novel groups was with 88% higher than with all known families of the order Chlamydiales. Four types of less frequent chlamydial 16S rRNA sequences were also detected. Two oligonucleotide probes were designed and optimized for catalyzed reporter deposition fluorescence in situ hybridization (CARD-FISH). Chl282 targets the cluster I and almost all other Chlamydiales while Chl282bis targets the cluster II and few other sequences. By these two probes we identified in the picoplankton abundant tiny cells with dot-shaped morphology and, interestingly, rarely also protists with intracellular pleomorphic chlamydiae. Abundances of the novel chlamydial clusters were up to 5 x 104 cells per ml. The presence of these two clusters was consistently registered in 2008, 2010 and 2013 sampling campaigns showing the relevance of environmental chlamydiae in Lago di Paola. This study enlarges the knowledge on the biodiversity of environmental chlamydiae in aquatic habitats raising sanitary issues that should be addressed in the future.

271 TUESDAY 10 SEPTEMBER 2013, 17:30 PS-5. Giving and getting: lifestyles of attached and symbiotic microbes

PS-5.19. SERUM-DEPENDENT INTERACTIONS OF VIBRIO AESTUARIANUS WITH BIVALVE HEMOCYTES

Monica Stauder, University of Genova (Italy) Coauthors: Pezzati E, Grande C, Bavestrello M, Canesi L, Vezzulli L, Pruzzo C

Crassostrea gigas and Mytilus spp. are the most important bivalves produced in Europe. While C. gigas production regularly suffers from mortality events, production of mussels is more stable. Different pathogens, including Vibrio strains, have been identified in many cases of oyster mortality. This study was planned to analyse the interactions of V. aestuarianus (as a model organism) with C. gigas and M. galloprovincialis hemocytes in vitro, and to decipher molecular basis for the different levels of sensitivity to disease displayed by the two mollusc species. It was found that, at 18°C, V. aestuarianus bacteria adhere to hemocytes of Mytilus and Crassostrea in the absence of serum (11±2 bacteria/hemocyte and 4±0.5 bacteria/hemocyte, respectively), but are sensitive to killing by hemolymph of M. galloprovincialis only. Serum capability to enhance adhesion to hemocytes is slightly higher in Mytilus than in Crassostrea. Serum mediated interactions of V. aestuarianus with hemocytes are inhibited by pre-treatment of bacteria with D- mannose in mussels (~50% reduction in comparison to control) but not in oysters, suggesting, among others, the possible presence of a mannose-containing opsonin in M. galloprovincialis serum. To investigate this, mussel serum was applied to a conA - agarose affinity column and the bound material was eluted with 0.5 M D-mannose. The resulting eluate, analyzed by SDS-PAGE, yielded a band of approximately 40 kDa. Experiments conducted with this fraction suggested it may play a role in mediating V. aestuarianus interactions with hemocytes. Overall, these results support the hypothesis that the lower sensitivity to Vibrio infection shown by M. galloprovincialis in comparison to C. gigas may also be dependent on more efficient serum-dependent interactions with hemocytes in mussels than in oysters.

272 TUESDAY 10 SEPTEMBER 2013, 17:30 PS-5. Giving and getting: lifestyles of attached and symbiotic microbes

PS-5.20. THE PHOTOTROPHIC COMMUNITY OF IKAITE TUFA COLUMNS IN IKKA FJORD, GREENLAND: DYNAMICS OF O2, pH, LIGHT AND PHOTOSYNTHETIC ACTIVITY IN AN EXTREME ENVIRONMENT

Erik Trampe, University of Copenhagen, Marine Biological Section, Helsingor (Denmark) Coauthors: Castenholz RW, Larsen JEN, Glaring M, Stougaard P, Kühl M

We present a detailed characterization of the physicochemical conditions and photosynthetic activity of phototrophs thriving in submarine tufa columns in Ikkafjord (SW Greenland). The columns are formed under very specific conditions from different carbonate minerals, in particular ikaite, a hexahydrate form of calcium carbonate. In situ underwater microsensor profiling of O2, pH and light dynamics revealed an extreme environment comprised by temperatures <6°C, low light, and gradients of highly alkaline fresh water (pH >10) meeting seawater (pH ~8). Cross sections of the columns revealed dense green bands of phototrophs ~1-2 cm into the freshly deposited ikaite matrix. Underwater O2 measurements as well as variable chlorophyll fluorescence imaging of photosynthesis and SEM imaging showed the presence of a productive cyanobacterial community dominated by filamentous morphotypes in the ikaite columns. We also present results of cultivation and molecular characterization of the phototrophic community in this unique ecological niche.

273 TUESDAY 10 SEPTEMBER 2013, 17:30 PS-5. Giving and getting: lifestyles of attached and symbiotic microbes

PS-5.21. NATURAL QUORUM SENSING INHIBITORS FROM PREVIOUSLY UNCULTURED MARINE BACTERIA

Hilla Ben-Hamo, , Laboratory of Biosensors and Microbiology, Department of Biotechnology Engineering, National Institute for Biotechnology in the NegevBen-Gurion University of the Negev Beer Sheva (Israel) Coauthors: Kushmaro A, Marks RS

The marine environment contains approximately 75% of all living organisms. Of these marine organisms many are microorganisms that have yet to be identified and cultured. These microorganisms may provide an important source for novel biomaterials, including antimicrobials. One exciting prospect is the discovery of quorum sensing (QS) inhibiting and inducing microorganisms especially those associated with marine invertebrates such as corals. These materials may provide important antimicrobial “replacements” in the 'post antibiotic era'. The goal of this study therefore, is to discover novel QS inhibition materials from coral associated marine bacteria, to characterize and elucidate their structure, and to then learn how to synthesize them. In order to achieve this, we used a technique developed in our lab whereby commonly unculturable microorganisms are encapsulated within agar spheres coated by polymeric membrane and incubated in the environment. The agar spheres entrap the microorganism while allowing molecules to diffuse in and out of the sphere. As proof of concept mucus associated bacteria from scleractinian corals were encapsulated in some spheres that were incubated in- situ on (near) the coral host surface. Primary screening of the spheres revealed that some showed QS inhibition.16S rRNA gene sequencing of the bacterial content of the spheres and subsequent phylogenetic analysis affiliated them to specific bacterial families. The chemical content of these spheres is being extracted and the chemical entities that may be responsible for the QS inhibition is being characterized using chemical analysis. The possible use of those compounds in medical application will be tested.

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TUESDAY 10 SEPTEMBER 2013, 17:30 PS-6. Genomics for a better understanding of the aquatic biogeochemical processes

PS-6.01. PARTICLE-ASSOCIATED BACTERIAL COMMUNITIES ARE EXTREMELY HETEROGENEOUS, YET DIFFER PROFOUNDLY BETWEEN LIMNIC AND MARINE SYSTEMS

Mina Bizic-Ionescu, Max Planck Institute for Marine Microbiology, Bremen (Germany) Coauthors: Zeder M, Ionescu D, Orlic S, Fuchs BM, Grossart HP, Amann R

Organic aggregates and associated microorganisms play a crucial role for organic matter cycling in both freshwater and marine systems. As hotspots for microbial activity they harbour microorganisms which may be underrepresented in the surrounding water. In this study, we compared particle-associated microbial communities in freshwater (Lake Stechlin and Grosse Fuchskuhle) with those in near-coastal marine systems (North Sea (Kabeltonne) and Northern Adriatic Sea). Fluorescence in Situ Hybridization (FISH) and semi-automated microscopy were used to analyze over 3000 individual aggregates from both environments for size, bacterial density and community composition. Aggregates were found to be on average larger in marine samples, yet more densely colonized in lakes. Particle-associated bacterial communities in limnic systems were dominated by Alphaproteobacteria and Betaproteobacteria, followed by Actinobacteria, Gammaproteobacteria and Bacteroidetes. Marine particles were colonized mainly by Alphaproteobacteria, Bacteroidetes and Gammaproteobacteria, but also Betaproteobacteria and Planctomycetes were detected. To compare the particle-associated communities at a higher phylogenetic resolution 454 pyrosequencing of partial 16S rRNA genes was performed. Limnic and marine particle-associated clades were increasingly separated with increasing taxonomic depth. For example the families Caulobacteraceae, Alcaligenaceae and Chitinophagaceae were among the most frequent on lake particles, whereas Rhodobacteraceae, Alteromonadaceae and Flavobacteriaceae were dominating marine particles. Despite a high particle to particle heterogeneity there were consistent phylogenetic differences between lake and sea water bacteria. Our data also show that some of the most abundant clades of free-living bacteria such as SAR11and SAR86 in the marine realm or LD12 and AcI in lakes are strongly depleted on particles. We conclude that any assessment of the diversity and community composition of bacterioplankton that excludes particles is necessarily incomplete, in particular with respect to organic matter mineralization.

275 TUESDAY 10 SEPTEMBER 2013, 17:30 PS-6. Genomics for a better understanding of the aquatic biogeochemical processes

PS-6.02. PHYLOGENETIC AND FUNCTIONAL CHARACTERIZATION OF NEW ORGANOHALIDE- RESPIRING BACTERIA IN A NATURAL LACUSTRINE ECOSYSTEM (LAKE PAVIN) USING HIGH- THROUGHPUT SEQUENCING AND GENE CAPTURE STRATEGIES

Corinne Biderre-Petit, LMGE UMR CNRS (France) Coauthors: Dugat-Bony E, Denonfoux J, Parisot N, Mege M, Peyretaillade E, Debroas D, Boucher D, Peyret P

Bacterial respiration has taken an advantage of almost every redox couple present in the environment. In anoxic compartments, organohalide respiration is a process allowing organohalide-respiring bacteria (OHRB) to use halogenated hydrocarbons as terminal electron acceptors during electron transport-based energy conservation. This process is catalysed by specific reductive dehalogenases (RdhA). Only bacteria belonging to Proteobacteria, Firmicutes and Chloroflexi are able to use this respiratory process and are categorized as obligate and non- obligate organohalide respirers. Whereas proteobacterial OHRB are all non-obligate organohalide respirers, all known OHRB affiliated to Chloroflexi (mainly Dehalococcoides strains) are obligate organohalide respirers. Since few decades, the Dehalococcoides trigger the greatest interest for their capacities to restore industrial sites contaminated by various chlorinated compounds and to dehalogenate completely chloroethenes to non-toxic ethene. Beyond bioremediation, the OHRB activities are part of the global halogen cycle, many organochlorine compounds being produced naturally in most ecosystems. However, few studies focused on the importance of this cycle in the functioning of uncontaminated freshwater ecosystems. In this work, the study was conducted on a natural lacustrine environment (Lake Pavin) located in the French Massif Central. The strategies were based on both the classical (cloning / Sanger sequencing) and high-throughput (shotgun and amplicon-based pyrosequencing) molecular methods and an innovative method based on a solution hybrid selection (SHS) gene capture, all targeting mainly 16S rRNA and rdhA genes. Analysis of sequencing data suggests that several OHRB inhabit this natural ecosystem. They belong both to the non-obligate proteobacterial OHRB (Geobacter, Sulfurospirillum, Desulfomonile) and to the obligate OHRB related to Chloroflexi. For Chloroflexi, at least 4 operational taxonomic unit were identified, one close to the known dehalorespirer genus Dehalogenimonas (97% identity) and 3 more distantly related to known cultured species (less than 87% identity). Gene capture approach allows us to isolate long genomic DNA fragments containing new rdhA sequences, 16S rRNA genes and Dehalococcoidetes homolog genes, revealing new genes organization. This study highlights the important diversity of the not yet studied OHRB living in natural ecosystems and opens the door to the discovery of new enzymes involved in halogenated compounds degradation.

276 TUESDAY 10 SEPTEMBER 2013, 17:30 PS-6. Genomics for a better understanding of the aquatic biogeochemical processes

PS-6.03. CHANGES IN METABOLIC ACTIVITY AND DIVERSITY OF THE BACTERIAL COMMUNITY DURING THE DEGRADATION OF ORGANIC MATTER FROM THE JELLYFISH AURELIA AURITA IN A MEDITERRANEAN COASTAL LAGOON

Blanchet M, Coauthors: Joux F, Pringault O, Catala P, Oriol L, Caparros J, Ortega-Retuerta E, Intertaglia L, Agis M, Bouvy M

In recent years, outbreaks of gelatinous plankton have increased in the Mediterranean Sea and caused socio-economic problems. The effect of these blooms on marine ecosystem functioning, and particularly on the role of heterotrophic bacteria in trophic dynamics, is still unclear. The response of the bacterial communities from a Mediterranean coastal lagoon (Bages, France) to the addition of dissolved organic matter (DOM) from the jellyfish Aurelia aurita was assessed during 22 days in microcosms. DOM from the jellyfish greatly stimulated bacterial abundance, production and respiration rates during the three first days and was followed by a sharp decrease in bacterial abundance. Bacterial growth efficiency remained lower than 20%, indicating that most of the DOM from A. aurita was respired. Bacterial diversity analysis, performed by a cultivation approach, DNA fingerprints and pyrosequencing indicated a rapid evolution of the bacterial community structure associated with the increase in Gammaproteobacteria abundance during the first days that was dominated by culturable bacteria belonging to the Pseudoalteromonas and Vibrio genus. After the decrease in bacterial abundance, the bacterial community was dominated by Bacteroidetes (94%, mainly Flavobacterium) more able to degrade polymers (susceptibility composed of peptidoglycan from lysed bacteria). After 22 days, high concentrations of ammonium and orthophosphate persist in the microcosms enriched in DOM, while the main part of dissolved organic carbon and nitrogen from A. aurita was consumed. At the end of the biodegradation process, the bacterial communities between the control and the microcosms enriched in DOM remained significantly different when the bacterial activities were similar.

277 TUESDAY 10 SEPTEMBER 2013, 17:30 PS-6. Genomics for a better understanding of the aquatic biogeochemical processes

PS-6.04. VIRAL METAGENOMICS: NEW INSIGHTS FROM ABYSSAL BENTHIC ECOSYSTEMS

Cinzia Corinaldesi, Department of Life and Environmental Science - DISVA, Polytechnic University of Marche (Italy) Coauthors: Dell’Anno A, Tangherlini M, Danovaro R

Viral assemblages are extraordinarily diverse and contain a high fraction of novel sequences with unknown functions. Despite there is evidence that deep-sea sediments can contain the largest microbial diversity on Earth, viral diversity is still almost unexplored in such ecosystems . We investigated, by using a metagenomic approach (by 454 pyrosequencing technology), several viromes from different deep-sea benthic ecosystems worldwide spanning Mediterranean, Atlantic, Pacific and Arctic sediments, from bathial to hadal depths (> 6000m). We found that viral diversity in deep-sea sediments worldwide is much higher than in shallow sediments, despite at hadal depths viral diversity decreases. The vast majority of viruses belongs to dsDNA families (Siphoviridae, Myoviridae and Podoviridae) and infects prokaryotic cells. Also the putative functional diversity in the viromes investigated is very high, particularly in the Mediterranean Sea, and the most represented functions are those related to the clustering-based systems, phages and prophages and protein metabolism. All viromes contain sequences dealing with auxiliary metabolic genes (AMGs), which allow us to hypothesize the relevance of horizontal gene transfer processes in benthic deep-sea ecosystems.

278 TUESDAY 10 SEPTEMBER 2013, 17:30 PS-6. Genomics for a better understanding of the aquatic biogeochemical processes

PS-6.05. TERRESTRIAL ORGANIC MATTER SUPPORTS MICROBIAL METABOLISM IN BROWN- WATER STREAMS

Christina Fasching, University of Vienna, Department of Limnology (Austria) Coauthors: Behounek B, Singer G, Wilhelm L, Battin T

The increasing export of terrestrial dissolved organic carbon (DOC) to freshwater ecosystems causes growing concern about ecosystem function and carbon cycling. Changes in climate and deposition chemistry are suggested to cause the elevated release of terrestrial organic carbon, which results in ‘browning’ of surface waters due to its strong absorbance of visible light. Given the net heterotrophy of most inland waters, increasing fluxes of terrestrial DOC may imply consequences for microbial metabolism and ultimately for carbon dioxide emissions from these inland waters. Yet, a possible effect of browning on ecosystem respiration and carbon cycling in headwaters and downstream ecosystems remains unclear. Here, we investigate the coupling of microbial metabolism and DOC characteristics along a gradient of DOC color in 20 headwater streams draining spatially independent catchments covered with coniferous forest and peatland in the Bohemian Massive, Austria. We employed bioassays to study carbon use efficiency (CUE) as a proxy for microbial metabolism and investigated DOC concentration, composition and bioreactivity to evaluate the effect of browning on ecosystem respiration. We found concurrent patterns of DOC concentration and the actual browning, but also clear concomitant shifts in DOC composition. Highly aromatic and humic-like compounds were a major contributor to DOC and subject to microbial metabolism in these streams. Streamwater CO2 partial pressure was mainly controlled by DOC concentration and CUE, which underscores the strong linkage between microbial physiology and DOC quality for ecosystem respiration. Hence, browning may significantly affect microbial metabolism and thus carbon cycling in headwater streams and downstream ecosystems.

279 TUESDAY 10 SEPTEMBER 2013, 17:30 PS-6. Genomics for a better understanding of the aquatic biogeochemical processes

PS-6.06. COMPARING DIFFERENT METHODS TO INFER DIVERSITY IN SYNECHOCOCCUS FROM 16S DATA

Diego Fontaneto, CNR-ISE, Verbania (Italy) Coauthors: Corno G, Callieri C, Coci M

Over the past decade, the availability of DNA sequence data from eukaryotes and the development of statistical and analytical tools linked to phylogenetic reconstructions allowed researchers to deepen our knowledge on patterns and processes in diversity. Several methods have been developed to use information on single locus sequences to identify potential groups indicative of independent evolution, akin to species. Among those, the most commonly used are (1) the barcoding approach with a fixed threshold of genetic distances within and between species, (2) the Automatic Barcode Gap Detector (ABGD), (3) the k/theta from population genetics, and (4) the Generalised Mixed Yule Coalescent method. For prokaryotes, the application of the barcoding approach is very common, whereas, the other methods have been rarely applied. Here we compare their use on an extensive dataset of 16S sequences from Synechococcus, in order to support the applicability of these methods also on prokaryotes.

280 TUESDAY 10 SEPTEMBER 2013, 17:30 PS-6. Genomics for a better understanding of the aquatic biogeochemical processes

PS-6.07. INFLUENCE OF BURIAL AND ENVIRONMENTAL FACTORS ON LAKE SEDIMENT MICROBIAL COMMUNITIES OVER A DEPTH-GRADIENT

Andrea Fuchs, Institut für Gewässerökologie und Binnenfischerei (IGB) Stechlin (Germany) Coauthors: Wurzbacher C, Frindte K, Attermeyer K, Allgaier M, Hupfer M, Grossart HP, Casper P, Monaghan M

Sediment microbial communities are influenced by a number of biotic and abiotic factors that vary with sediment depth, and compete for available resources. We studied two aspects influencing microbial community composition in sediments: On one hand, we examined chemical parameters and sediment quality. On the other hand, we considered burial due to varying sedimentation in consecutive years as a factor. Comprehensive measurements of environmental parameters and amplicon pyrosequencing using universal SSU rRNA primers were performed in 15 layers of four 30 cm sediment cores taken along a small transect (~ 30 m water depth) in Lake Stechlin in northern Germany. A long-term study (> 40 years) enabled the comparison of recorded plankton and chemical data of the water column with genomic sequences and porewater profiles found in the sediment. For example, evidence for historical events such as the phosphate- and plankton- enriched years 1995-1997 was found in the sediment layers. Eukaryotic DNA was found to be gradually degraded within the upper 10 cm and almost vanished below that horizon. Bacterial and archaeal DNA were present at all depths, with an increasing relative abundance of Archaea with depth. Mantel tests showed that Bacteria form the link connecting eukaryotic material to archaeal communities. Single environmental parameters could not explain community compositions in any sediment layer. At 10 cm depth, a radical change of several parameters was observed: above this layer concentrations of Ca, Cu, Cd and Zn were considerably increased, while opposingly below this depth archaeal DNA reads occurred in high abundance. The results obtained by amplicon pyrosequencing give new insights in sediment community structure and prove to be valuable in estimating the impact of environmental factors on microbial life in sediments.

281 TUESDAY 10 SEPTEMBER 2013, 17:30 PS-6. Genomics for a better understanding of the aquatic biogeochemical processes

PS-6.08. REGULATIVE ADAPTION OF SAR11 TO IRON-LIMITATION

María Jesús Gálvez Zenteno, Oceanography department, University of Concepción (Chile) Coauthors: Molina V, Fourquez M, Blain S, Obernosterer I, Beier S

It is now well established that iron limits autotrophic and heterotrophic processes in large regions of the ocean. However, most investigations on iron limitation are focused on phytoplankton, while its effect on marine heterotrophic bacteria is less documented. Iron is crucial in a large number of biological reactions, acting both as an electron carrier and an enzymatic cofactor. In aerobic cells, the production of energy is mainly achieved by respiration that uses iron-containing enzymes. Among this process, the tricarboxylic (TCA) acid cycle is a central step, which could be directly affected by iron-limitation as it possesses three iron-containing enzymes. The glyoxylate cycle is another pathway that bypasses the oxidation steps of the TCA cycle. Our aim is to test the idea that the glyoxylate cycle may be used as a compensatory mechanism for heterotrophic bacteria to cope with iron-limitation. Our hypothesis is that the expression of the main enzyme of this bypass, the isocitrate-lyase, is elevated when marine bacteria are iron-limited. We collected samples at iron-depleted sites and in different naturally iron-fertilized regions off Kerguelen Island (Southern Ocean) during the KEOPS2 cruise. Single-cell analyses revealed that SAR11 was abundant (36-63% of DAPI-cells) and active (41-70% of Leu-active DAPI-cells) in surface waters at all sites. We have developed primers that specifically amplify the isocitrate-lyase of SAR11-like organisms. In order to learn more about gene-regulation induced by iron-limitation in marine bacteria we will use these primers in a qCR approach to quantify isocitrate-lyase copy numbers in the genome and transcriptom of SAR11-like organisms.

282 TUESDAY 10 SEPTEMBER 2013, 17:30 PS-6. Genomics for a better understanding of the aquatic biogeochemical processes

PS-6.09. THE ROLE OF PHOTOREACTIVE IN ALGAE-BACTERIA INTERACTIONS IN SITU

Astrid Gärdes, Leibniz Center for Tropical Marine Ecology ZMT, Bremen (Germany) Coauthors: Triana C, Amin SA, Green DH, Romano A, Trimble L, Carrano CJ

Certain phytoplankton may have a symbiotic association with specific bacterial species driven by a mutualistic sharing of photosynthetically fixed organic carbon and heterotrophic remineralization of limiting nutrients. We proposed the existence of a specific mutualism between vibrioferrin (VF) producing Marinobacter and members of the dinoflagellate and coccolithophore algal lineages. This photolytically active siderophore VF provides an enhanced supply of Fe(III)’ to the algae and in return the bacteria would benefit from the release of photosynthate supporting their growth. To provide evidence for this bacterial-algal association we analyzed bacterial community structures with emphasis on the in situ abundance and succession of Marinobacter species inside and outside phytoplankton blooms. Using in situ fluorescence hybridization (FISH) and Marinobacter specific probes we could determine the correlation of certain Marinobacter species with dinoflagellate blooms. Furthermore we detected vibrioferrin biosynthetic genes using quantitative Real-Time PCR (qPCR) and analyzed the importance and abundance of other marine photoreactive siderophores like aerobactin and petrobactin. With this we hope to estimate the potential role of photoreactive siderophores in oceanic iron cycling and their contribution to bacteria-algal mutualism in correlation to phytoplankton blooms.

283 TUESDAY 10 SEPTEMBER 2013, 17:30 PS-6. Genomics for a better understanding of the aquatic biogeochemical processes

PS-6.10. TEMPORAL CHANGES IN ARCHAEAL COMMUNITY ACTIVITY AND AMMONIA OXIDIZING ARCHAEA DYNAMICS ALONG AN ESTUARINE SALINITY GRADIENT

Mylène Hugoni, Laboratoire Microorganismes: Génome et Environnement - UMR CNRS 6023 (France) Coauthors: Agogué H, Taib N, Domaizon I, Moné A, Galand PE, Bronner G, Debroas D, Mary I

Estuaries can host a high biodiversity because of their position at the interface between terrestrial and marine environments. However the activity and diversity of archaeal communities, and especially Ammonia Oxidizing Archaea (AOA), and their response to physico-chemical gradients are not well known. To evaluate the influence of salinity and other environmental factors on diversity and distribution of active Archaea and AOA, 16SrRNA and amoA transcripts were pyrosequenced along a salinity gradient in the pelagic zone of the Charente Estuary (Atlantic coast, France). Archaeal amoA transcripts were quantified through an entire year, as well as the thaumarchaeal ureC transcripts, that could represent evidence of an alternative pathway that use urea to fuel ammonia oxidation. The results were compared to bacterial amoA transcripts abundances to assess the relative contribution of each domain in estuarine nitrification process. The limnetic station was characterized by a co-occurrence of both active methanogenic lineages and Thaumarchaeota Marine Group I (MGI), associated with a predominance of active Ammonia Oxidizing Bacteria over AOA. In this station, archaeal amoA dynamics was closely related to ureC dynamics. The mesohaline station was dominated by active MGI all year-round, associated with active AOA more abundant from April to September. In contrast, in the euhaline station, Euryarchaeota Marine Group II, commonly retrieved in the marine water column, dominated the archaeal assemblage during summer, while active MGI were related to the winter period associated to a maximal abundance of amoA transcripts. Interestingly, AOA diversity retrieved in this study was exclusively related to the Nitrosopumilus lineage

284 TUESDAY 10 SEPTEMBER 2013, 17:30 PS-6. Genomics for a better understanding of the aquatic biogeochemical processes

PS-6.11. SHIFTS IN SEDIMENT PROKARYOTIC COMMUNITY STRUCTURE AND FUNCTION ALONG AN ESTUARINE SALINITY GRADIENT AND ITS ROLE ON NITRIFICATION PROCESS

Maria Monteiro, Interdisciplinary Centre of Marine and Environmental Research, Porto (Portugal) Coauthors: Santoro A, Gomes N, Magalhaes C

In this study we investigated the dynamics of Archaea and Bacteria diversity along the salinity gradient of the Douro estuary (NW Portugal). Sediment samples were collected at four sites covering a gradient of salinity ranging from 21.7 to 4.9 psu. Two fingerprinting methods (DGGE, ARISA) were used to evaluate structural differences between bacterial and archaeal communities and the results were concordant by indicating a clear decrease of archaeal diversity with the progressive increase of salinity. Bacterial communities were found to be more diverse than archaeal ones, but not so much affected by changes in water salinity. Nitrification rates were also measured on sediment slurries and intact cores, by using an acetylene block technique and 15N isotopic analysis. From the acetylene method, nitrification rates ranged from 6.75 to 14.35 nmol + -1 -1 NH4 g sed. h and statistical differences were detected between two of the four sites. Finally, bacterial and archaeal amoA diversity and abundance were also evaluated by DGGE and qPCR respectively, to determine the relationships between abundance and diversity of the two groups of ammonia oxidisers with the nitrification rates previously measured. This study will allow us to get important insights into the role of prokaryote communities on ammonia oxidation step of nitrification conditioned by a salinity gradient and will increase our knowledge on the nitrogen cycle biology.

285 TUESDAY 10 SEPTEMBER 2013, 17:30 PS-6. Genomics for a better understanding of the aquatic biogeochemical processes

PS-6.12. ULTRAHIGH-RESOLUTION MOLECULAR CHARACTERIZATION OF DOM IN GLACIER-FED AND CLEAR ALPINE LAKES

Laurent Moya, University of Innsbruck, Institute of Ecology, Lake and Glacier Ecology Research Group (Austria) Coauthors: Peter H, Dittmar T, Sommaruga R

A remarkable characteristic of glacier-fed lakes is their high content of suspended minerogenic particles, so-called 'glacial flour'. The current rapid glacier retreat is expected to increase turbidity in glacier-fed lakes with consequences for the primary production and UV penetration. At the same time, the rapid glacier retreat my lead to the loss of connectivity to lakes that then became clear. In combination, these processes may have consequences for the composition of Dissolved Organic Matter (DOM) and its diversity. We hypothesized that diversity of dissolved organic molecules increases with decreasing turbidity due to the change in contribution of phytoplankton- derived carbon. We used Fourier-Transform Ion Cyclotron Mass Spectrometry to assess the molecular composition and diversity of DOM in four interconnected lakes in the Austrian Alps over the ice-free season. This analysis was complemented with spectrophotometric and fluorometric measurements. Three of the lakes receive water from a glacier and exhibited a turbidity gradient, whereas one lake lost contact to the glacier and it is clear. Our results showed that DOM composition differed between all lakes and showed substantial seasonal variation. In terms of diversity, the clear lake had not only 16% to 20% more organic molecules than the turbid lakes, but also 12-fold more unique ones. These results suggest that the increase in DOM diversity with decreasing turbidity will sustain a higher prokaryotic diversity in clear lakes.

286 TUESDAY 10 SEPTEMBER 2013, 17:30 PS-6. Genomics for a better understanding of the aquatic biogeochemical processes

PS-6.13. ECOGENOMIC TRACING OF TROPHIC CONNECTIVITY IN TROPICAL COASTAL AND COMMUNITIES

Tom Rayner, Charles Darwin University, Darwin (Australia) Coauthors: Nelson T, Jardine T, Douglas M, Bunn S

Seasonal river flows drive food web structure and function in tropical rivers, by regulating connections between marine, estuarine and freshwater habitats and driving cyclic changes in productivity. As highly-mobile consumers, fish play an important role in the transport of energy both vertically (up and down food chains) and horizontally (up and down river systems) at spatial and temporal scales ranging from small (across microhabitats over days to weeks) to large (across landscapes over months to years). Previous research has documented strong relationships between river flows, habitat and food availability (Rayner et al. 2008), fish feeding (Rayner et al. 2009) and food web function (Rayner et al. 2010). However, drawing definite and meaningful conclusions from traditional methods, particularly stable isotope data has been, and remains, challenging. This project is developing a novel approach, based on next-generation sequencing, to identify and trace bacterial species, functional guilds and communities through the aquatic food chain, from basal resources to fish and other higher predators (e.g., saltwater crocodiles) in Kakadu National Park, Australia. This study area is of significant social, cultural and environmental value for both indigenous and non-indigenous peoples. Paired stable isotope (fin clip) and gut bacteria (swab) samples have been collected from approximately 100 individual fish across 10 species from two large, floodplain billabongs. Preliminary isotope data reveal strong compartmentalisation of food web structure across habitat scales. This poster will compare these data with insights gained using sequence data and assess the potential for the method to provide far greater resolution of trophic links between important fish species and their prey.

287 TUESDAY 10 SEPTEMBER 2013, 17:30 PS-6. Genomics for a better understanding of the aquatic biogeochemical processes

PS-6.14. SALINITY AS A KEY REGULATOR OF DMSP CATABOLISM PATHWAYS IN ESTUARINE SEDIMENTS AND IN RUEGERIA POMEROYI PURE CULTURE

Paula Salgado, Centre of Marine and Environmental Research, University of Porto (Portugal) Coauthors: Kiene R, Bordalo A, Magalhaes C

Marine emissions of dimethyl sulfide (DMS) to the atmosphere represent an important contribution for global climate balance. This sulfur compound derives mainly from the degradation of dimethylsulfoniopropionate (DMSP) through the enzymatic cleavage pathway, which is a microbially-mediated process. Additionally, DMSP can also be degraded via a competing catabolic route involving demethylation/demethiolation which yields methanethiol (MeSH). This study evaluated the influence of salinity variations (0 – 30 ppt) on DMS and MeSH net production in sediment slurries and in Ruegeria pomeroyi cell suspensions amended with different DMSP concentrations (0 – 500 µM). We monitored the accumulation of the volatile sulfur compounds (MeSH, DMS) by gas-chromatography (GC-PFPD). Experimental increases of salinity revealed an opposite pattern between DMS and MeSH accumulations in both sediment slurries and R. pomeroyi DSS-3 cell suspension experiments with lower salinities favouring net DMS production while higher salinities favoured higher MeSH accumulation. The concordant results observed between natural complex communities (estuarine sediment slurries) and R. pomeroy cell suspensions, suggests that salinity is a key environmental factor affecting the net outcome of the two competing enzymatic pathways of DMSP degradation and ultimately the net accumulation of DMS and/or MeSH derived from DMSP catabolism.

288 TUESDAY 10 SEPTEMBER 2013, 17:30 PS-6. Genomics for a better understanding of the aquatic biogeochemical processes

PS-6.15. ISOLATION OF STRICTLY ANAEROBIC AND HALOPHILIC REPRESENTATIVES OF DEEP BRANCHING PHYLOGENETIC LINEAGES WITHIN THE PVC SUPERPHYLUM

Stefan Spring, Leibniz Institute DSMZ-German Collection of Microorganisms and Cell Cultures, Braunschweig (Germany) Coauthors: Spröer C, Klenk HP

In hypersaline lakes on the Kiritimati Atoll (Kiribati, Central Pacific) laminated photosynthetic microbial mats were found that are characterized by conspicuous mineral deposits. The microbial population inhabiting the deep anoxic zone of these mats was studied using cultivation-dependent methods. Most of the isolated strains were either saccharolytic fermentative bacteria or incompletely-oxidizing sulfate reducers that likely drive the anaerobic decomposition processes in this habitat. Two of the strictly anaerobic saccharolytic strains, L21-RPul-D3 and L21-Fru-AB, had a coccoid morphology and excreted polymeric compounds that increased medium viscosity. Both strains could be affiliated to the Planctomycetes-Verrucomicrobia-Chlamydiae (PVC) superphylum based on comparative 16S rRNA sequence analyses. Strain L21-RPul-D3 is the first cultured representative within the ML-A-10 cluster of cloned 16S rRNA sequences that comprise a tentative novel order within the class Phycisphaerae. Strain L21-Fru-AB represents the first cultured isolate within subdivision 5 of the phylum Verrucomicrobia. The newly isolated strains seem to be indigenous to anoxic niches within hypersaline microbial mats, because almost identical 16S rRNA sequences were also retrieved from the Guerrero Negro microbial mat, whereas similarity values to environmental sequences from all other habitats were below 88%. Draft genome sequences of both strains were determined and results based on comparative genome analyses with other representatives of the PVC superphylum will be presented.

289 TUESDAY 10 SEPTEMBER 2013, 17:30 PS-6. Genomics for a better understanding of the aquatic biogeochemical processes

PS-6.16. DIVERSITY, ACTIVITY, AND DISTRIBUTION OF SULFUR-OXIDIZING BACTERIA IN SEDIMENTS: EVIDENCE FOR SPATIO-TEMPORAL HETEROGENEITY AND PLANT-MICROBE INTERACTIONS

Francois Thomas, Woods Hole Oceanographic Institution, Massachusetts (USA) Coauthors: Giblin A, Cardon Z, Sievert S

Salt marshes are highly productive ecosystems and act as a buffer at the land/ocean interface. Rates of sulfate reduction are among the highest reported in the marine environment, resulting in the production of sulfide that is potentially available for chemolithotrophic microorganisms. However, the microbes involved in the oxidative portion of the S-cycle in salt marsh systems, and their biogeochemical roles, have remained obscure. The present study provides the first in-depth assessment of S-oxidizers in salt marsh sediments colonized by the dominant plant Spartina alterniflora. We characterized the total and active bacterial communities thriving in the sediments or being associated with roots in marshes at Plum Island Estuary (Massachusetts, USA). Phylogenetic analyses of 16S rRNA and genes involved in two distinct S-oxidation pathways (soxB and rdsrAB) revealed a diverse community comprising relatives of known sulfur-oxidizing bacteria, i.e., members of the Alpha-, Gamma- and Epsilonproteobacteria. qPCR assays were developed to quantify gene and transcript numbers for 13 different soxB and rdsrAB phylotypes in samples from two sites, in Spring, Summer and Fall. Overall the rdsrAB genes, and notably a Chromatiales- related phylotype, were more abundant and expressed than soxB. The results also unveiled some macroscale (between sites) and microscale (roots vs. sediment) spatial heterogeneities. Interestingly, the abundance and expression of Epsilonproteobacteria-related soxB genes tended to increase on Spartina roots compared to the surrounding sediments. These data suggest an interaction between S-oxidizers and Spartina roots, which might constitute preferential microniches for S-based in salt marshes.

290 TUESDAY 10 SEPTEMBER 2013, 17:30 PS-6. Genomics for a better understanding of the aquatic biogeochemical processes

PS-6.17. GENOME SEQUENCES OF NOVEL ISOLATES OF LIMNIC AEROBIC ANOXYGENIC PHOTOTROPHIC BACTERIA SUGGEST A COMPLEX EVOLUTION PATTERN OF PHOTOSYNTHESIS GENE CLUSTER AMONG PROTEOBACTERIA

Yonghui Zeng, Institute of Microbiology ASCR, Trebon (Czech Republic) Coauthors: Koblizek M

Aerobic anoxygenic phototrophs (AAPs) are prokaryotic organisms containing reaction centers composed of bacteriochlorophyll a (BChl a). AAPs represent an important part of microbial communities inhabiting the euphotic zone of world oceans and lakes. In contrast to the extensive studies of marine AAPs, only little is known about their presence and diversity in limnic habitats. A recent study of the diversity of AAP community in a German lakes suggested that freshwater species belong to α- and β-proteobacteria. So far only a limited number of limnic AAPs exist in pure cultures, which constrains our knowledge on their metabolism, physiology and their role in biogeochemical fluxes. For this reason we decided to isolate representative AAP species from various limnic environments. We developed a rapid isolation protocol which employs fluorescence screening of AAP colonies directly on agar plates using an infrared CCD camera. We obtained over 200 isolates from different types of freshwater lakes located in Austria, Czech Republic and China (a fishpond, a low-elevation volcanic lake, a highly contaminated lake, and a clear Tibetan plateau lake). Analyses of 16S rRNA gene sequences suggest most of the strains were affiliated with α-proteobacteria belonging to genera Afipia, Agrobacterium, Bosea, Brevundimonas, Methylobacterium, Novosphingobium, Phyllobacterium, Porphyrobacter, Rhizobium, Rhodocista, Rhodopseudomonas, Sandarakinorhabdus, and Sphingomonas. Nine isolates were β-proteobacteria belonging to genera Caenimonas, Ideonella, Leptothrix, and Methylibium. We also isolated one γ-proteobacterial AAP strain from the Huguangyan Maar Lake, South China, which has not been reported from a freshwater lake before. An analysis of pufL, pufM, and bchY genes sequence suggests a complex phylogenetic history of phototrophic genes in AAP species. Further, we carried out whole genome sequencing on 27 representative strains using Illumina technology. Complete photosynthesis gene clusters (PGC) were successfully assembled from the sequence data for most of the genomes. Together with available AAP genomes from some marine isolates in public database, these data for the first time enable us to make an insightful comparison of PGC composition and their possible evolutionary history among Proteobacteria.

291 TUESDAY 10 SEPTEMBER 2013, 17:30 PS-6. Genomics for a better understanding of the aquatic biogeochemical processes

PS-6.18. HOW DIMETHYLSULFONIOPROPIONATE DEGRADATION COMPOUNDS MAY CONTROL THE EFFICIENCY OF DENITRIFICATION PATHWAY

Catarina Magalhães, CIMAR/CIIMAR - Centre of Marine and Environmental Research, University of Porto (Portugal) Coauthors: Salgado P, Buchan A, Machado A, Wiebe WJ, Kiene RP

Aerobic anoxygenic phototrophs (AAPs) are prokaryotic organisms containing reaction centers composed of bacteriochlorophyll a (BChl a). AAPs represent an important part of microbial communities inhabiting the euphotic zone of world oceans and lakes. In contrast to the extensive studies of marine AAPs, only little is known about their presence and diversity in limnic habitats. A recent study of the diversity of AAP community in a German lakes suggested that freshwater species belong to α- and β-proteobacteria. So far only a limited number of limnic AAPs exist in pure cultures, which constrains our knowledge on their metabolism, physiology and their role in biogeochemical fluxes. For this reason we decided to isolate representative AAP species from various limnic environments. We developed a rapid isolation protocol which employs fluorescence screening of AAP colonies directly on agar plates using an infrared CCD camera. We obtained over 200 isolates from different types of freshwater lakes located in Austria, Czech Republic and China (a fishpond, a low-elevation volcanic lake, a highly contaminated lake, and a clear Tibetan plateau lake). Analyses of 16S rRNA gene sequences suggest most of the strains were affiliated with α-proteobacteria belonging to genera Afipia, Agrobacterium, Bosea, Brevundimonas, Methylobacterium, Novosphingobium, Phyllobacterium, Porphyrobacter, Rhizobium, Rhodocista, Rhodopseudomonas, Sandarakinorhabdus, and Sphingomonas. Nine isolates were β-proteobacteria belonging to genera Caenimonas, Ideonella, Leptothrix, and Methylibium. We also isolated one γ-proteobacterial AAP strain from the Huguangyan Maar Lake, South China, which has not been reported from a freshwater lake before. An analysis of pufL, pufM, and bchY genes sequence suggests a complex phylogenetic history of phototrophic genes in AAP species. Further, we carried out whole genome sequencing on 27 representative strains using Illumina technology. Complete photosynthesis gene clusters (PGC) were successfully assembled from the sequence data for most of the genomes. Together with available AAP genomes from some marine isolates in public database, these data for the first time enable us to make an insightful comparison of PGC composition and their possible evolutionary history among Proteobacteria.

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MONDAY 9 SEPTEMBER 2013, 17:30 PS-7. What omics can (and can't) tell us about microbial ecology

PS-7.01. OPTIMIZED ASSEMBLY AND PROBABILISTIC BINNING FOR METAGENOMIC GENOME RECONSTRUCTION

Anders Andersson, KTH Royal Institute of Technology (Sweden) Coauthors: De Bruijn I, Alneberg J, Smari-Bjarnason B, Loman N, Quince C

Metagenomics enables us to reveal the taxonomic composition and functional potential of complex microbial communities without the need for culturing. It also makes it possible to reconstruct the genomes of individual organisms within the community through assembly of short sequence reads into longer genome fragments (contigs and/or scaffolds) and clustering these into species level groups (binning). These procedures are however challenging because a mixture of often closely related organisms lead to complications in the assembly process as well as difficulties in the binning due to similarities in sequence signatures. Here we have evaluated different combinations and parameter settings of a range of assembly and scaffolding programs for the ability to generate long and error free contigs/scaffolds from a model microbial community consisting of 59 prokaryotic strains of varying relatedness that was paired-end sequenced by Illumina HiSeq. Moreover we have developed a probabilistic binning method that uses a combination of sequence signatures (kmer frequencies) and information on co-occurrence across multiple samples to cluster contigs in a probabilistic manner. We demonstrate the usefulness of our optimized assembly strategy and novel binning method on both simulated and real metagenomic datasets.

293 MONDAY 9 SEPTEMBER 2013, 17:30 PS-7. What omics can (and can't) tell us about microbial ecology

PS-7.02. DESIGN OF NOVEL SSU RDNA PRIMERS USING DEGEPRIME

Luisa Hugerth, Royal Institute of Technology (KTH), Solna (Sweden) Coauthors: Hu Y, Wefer H, Andersson AF

The advent of massively parallel sequencing has opened a new age for microbial ecology, allowing environmental samples to be relatively simply, cheaply and quickly probed for the entirety of their microbial diversity, bypassing culturing biases. When the goal of a study is to identify and classify microbial communities, amplicon sequencing of marker genes such as 16S rDNA, 18S rDNA or fungal ITS is often preferred over shotgun sequencing. Amplicon sequencing has the advantage of minimizing bioinformatic post-processing and leveraging on the large databases available for these well-studied genes. However, a poor choice of primer can lead to severe biases in diversity assessment, and leave out entire phyla from a survey. DegePrime is a tool designed to find the oligomer of defined length and maximal degeneracy of highest coverage for each position of a multiple alignment – that is, the degenerate oligomer that matches the largest number of sequences in each position. DegePrime thus solves the "maximum coverage degenerate primer design problem", using a novel heuristic for this. As taxonomic bias is an important concern for environmental sample sequencing, DegePrime further offers a functionality that converts Genbank files into taxonomic annotations and allows users to assess the coverage of selected primers for each taxon at different taxonomic levels. The quality of primers generated by DegePrime is demonstrated here through the presentation of novel and improved primer pairs for 16S and 18S rDNA and their application in Illumina amplicon sequencing of various environmental samples, and comparison to results obtained by shotgun metagenomics.

294 MONDAY 9 SEPTEMBER 2013, 17:30 PS-7. What omics can (and can't) tell us about microbial ecology

PS-7.03. TIME TO LOOK AT SINGLE MICROBIAL-CELLS: THREE EXAMPLES OF THE USEFULNESS OF SINGLE CELL SEQUENCING

Manuel Martinez-Garcia, University of Alicante (Spain) Coauthors: Swan B, Poulton N, Brazel D, Arnosti C, Chain P, Sieracki M, Stepanauskas R

It is well known that cultivation techniques do not recover the vast majority of uncultured microbes in nature. To circumvent these limitations, past and current efforts based on metagenomics have significantly and unquestionably broadened our knowledge in microbial ecology. However, despite improvement of assembly, metagenomics largely fails to recover discrete genomes from uncultured key microorganisms and to address some fundamental biological questions. Recently, single cell genomics has emerged as a new and powerful strategy, opening thus new avenues to disentangle the genomic information of most uncultured microbial groups. This presentations aims to show the usefulness of single cell-genomics in aquatic systems by presenting our work carried out in the last two years in different contrasting topics. For instance, we unveiled the unexpected role of marine Verrucomicrobia as major biopolymer bacterial degraders in planktonic systems. Single cell sequencing results of a predominant widespread coastal verrucomicrobia showed that it possessed a vast and complex metabolic machinery involved in polysaccharide hydrolysis with an exceptional genomic enrichment of glycoside hydrolase genes compared to other prokaryote groups besides a considerable amount of peptidases, indicating thus that likely Verrucomicrobia is a key biopolymer degrader. Another example is the in situ identification of major uncultured protists, such as MAST4, interacting with prokaryotes in marine systems. Despite the role of protists, yet little is known about their in situ prey-preferences or symbiotic interactions. In this work, we partly elucidated and demonstrated the use of single cell to unravel ecological interactions between major uncultured protists and bacteria. Finally, the powerful combination of metagenomics and single-cell technologies resulted in the identification of predominant freshwater photoheterotrophic and chemoautotrophic bacteria. These, together with other studies are only the tip of the iceberg, and along with the coming "lab on a chip- technologies" will spur on microbial ecologists to swim in a sea of single-cell microbes.

295 MONDAY 9 SEPTEMBER 2013, 17:30 PS-7. What omics can (and can't) tell us about microbial ecology

PS-7.04. PROTEOME BASED COMPARATIVE ANALYSIS OF EXPONENTIALLY GROWING AND STATIONARY PHASE MARINE BACTERIA

Saraladevi Muthusamy, Linnaeus University, Kalmar (Sweden) Coauthors: Baltar F, Lundin D, Branca MR, Lehtiö J, Pinhassi J

Marine bacteria play key roles in biogeochemical processes. Modern proteomics techniques coupled with the availability of genomic sequence data provide an unprecedented opportunity to compare proteome profiles of individual microorganisms, to understand the cellular responses and physiology that determines the ecology of marine bacteria. We developed high throughput proteomic approaches to compare the proteome profiles for three model organisms representative of major marine bacterioplankton lineages [i.e., Alphaproteobacteria (Roseobacter MED193), Gammaproteobacteria (Neptuniibacter MED92) and Flavobacteria, (Dokdonia MED134)]. Bacteria were grown in seawater media with complex organic matter, and we quantified expressed proteins during exponential growth compared to stationary phase by liquid chromatography coupled with tandem mass spectrometry (Nano LC-MS/MS). For each of the three bacteria, around 700 proteins out of approximately 3000 detected (from an average of 3700 predicted proteins in the genomes) were significantly differentially regulated, with 2-16 fold differences in expression level. Consistent with expectations in all bacteria, proteins that are involved in protein biosynthesis (e.g. ribosomal proteins) and signal transduction were strongly up regulated in exponential phase. In contrast, upon entry into stationary phase, proteins essential for survival and that promote microbial competitive ability were up regulated. Notably, while the bacteria shared responses in universal stress proteins, important differences between bacteria were found in the expression of e.g. ABC transporters (dominant in Roseobacter MED193), chemotaxis (dominant in Neptuniibacter MED92) and TonB and several putative uncharacterized proteins in (Dokdonia MED134). Our results highlight that natural selection has resulted in relatively similar basic cellular adaptations in different marine bacterial lineages to successfully compete in nutrient rich environments. On the other hand, the adaptations to adverse conditions appear to be much more divergent. This has important implications for interpreting bacterial responses to changing growth conditions in the sea.

296 MONDAY 9 SEPTEMBER 2013, 17:30 PS-7. What omics can (and can't) tell us about microbial ecology

PS-7.05. PREDICTION OF OCEAN-WIDE BIOTIC AND ABIOTIC INTERACTIONS

Gipsi Lima-Mendez, Vrije Universiteit Brussel/VIB (Belgium) Coauthors: Faust K, Sunagawa S, Audic S, Acinas SG, Ogata H, Wincker P, de Vargas C, Karsenti E, Raes J, Tara-Oceans Consortium

The structure and dynamics of the oceans result from the interplay between the inhabitant organisms and the physical component of the environment. These biotic and abiotic factors are all linked together through energy flow and nutrient cycles. In marine environments, the plankton provides the basis of the food web. We inferred ecological interactions between species such as competition, symbiosis and predation, etc, from the comparison of the species-occurrence profiles. Using a dataset collected from 36 diverse sampling sites from around the world during the Tara Oceans expedition we have performed an end-to-end screening of plankton communities within the euphotic zone, including viruses, prokaryotes, phytoplankton and zooplankton. We use the species abundances obtained from V9 18S pyrotags and 16S RNA metagenomic reads to infer networks, where edges represent pair-wise relationships between taxonomic units that tend to co-occur across different samples. The analysis of these pairwise links given the environmental conditions across the samples allows distinguishing associations explained by environment alone from those where both environmental and biotic factors seemed to contribute.

297 MONDAY 9 SEPTEMBER 2013, 17:30 PS-7. What omics can (and can't) tell us about microbial ecology

PS-7.06. FROM NORTH TO SOUTH: MICROBIAL DIVERSITY ALONG A LATITUDINAL TRANSECT IN THE ATLANTIC OCEAN

Mathias Milici, Helmholtz Center for Infection Research, Braunschweig (Germany) Coauthors: Wang H, Sandoval R, Tomasch J, Wos-Oxley M, Pieper D, Wagner-Döbler I

High-throughput sequencing of 16S rRNA amplicons allows a higher resolution of the microbial community structure than traditional methods. The Illumina sequencing platform permits to generate millions of sequences in parallel from different samples, in a relatively small time. Furthermore it reduces greatly the cost of sequencing, compared with the Sanger method and the 454 pyrosequencing. This approach provides a new vigor to the survey of the microbial communities. The aim of this work is to assess the diversity and abundance of marine bacterioplankton communities of the photic zone from the subantarctic South Atlantic (51°S) to the temperate North Atlantic (47°N). Samples were collected at 26 stations during the cruise ANT XXVIII/5 of the research vessel Polarstern at fixed depths between 20 and 200 meters using a rosette sampler on which a CTD instrument was mounted. 20 L of water were collected per depth and sequentially filtered on membrane filters of 8, 3 and 0, 22 µm pore width. DNA was extracted using the UltraClean Soil DNA Isolation Kit (Mobio) with a chemical pre-lysis step to achieve the lysis of all the cells. Samples will be analyzed by sequencing of a hyper-variable fragment of the universally conserved, 16S ribosomal RNA gene using the Illumina sequencing platform. Such data will be combined with abiotic (for example: nutrients, chlorophyll a, DOC and DOM) and biotic (for example: phytoplankton and bacterial abundance) parameters that well define the water column and the environment, to investigate possible patterns of the distribution and the abundance of the OUT´s detected in our molecular survey. The amplicon data will be used to select some samples for the metatranscriptomic analysis, to assess which members of this community are really active in the water column and in particular to define and characterize those members of the community that are able to produce and provide B vitamins to algae with the goal to better understand the role and the activity of the microbial community and its relation with phytoplankton.

298 MONDAY 9 SEPTEMBER 2013, 17:30 PS-7. What omics can (and can't) tell us about microbial ecology

PS-7.07. PROMOTER MAPPING AND FULL TRANSCRIPTOME ANALYSIS OF TRICHODESMIUM ERYTHRAEUM ACCLIMATED TO DIFFERENT SALINITIES

Ulrike Pfreundt, Institute for Biology III, AG Hess, Freiburg (Germany) Coauthors: Kopf M, Belkin N, Berman-Frank I, Hagemann M, Hess W

Cyanobacteria of the genus Trichodesmium are responsible for a large amount of newly fixed nitrogen in the world’s oceans. Understanding how these abundant photosynthetic bacteria can thrive and fix nitrogen in low iron, high salinity environments like the Red Sea, but also in the lower-salinity oceans, will enable better predictions as to how these important players might react to future global changes in temperature and chemical composition. While the genome sequence of the strain T. erythraeum IMS101 is available in data bases, no transcriptome study of Trichodesmium is published. Transcriptomics using RNAseq allows not only for an overview on all transcribed genes including non-protein-coding RNAs (ncRNAs); it also allows for mapping of promoters and the study of environmental impacts on gene expression. For example, Trichodesmium’s osmoregulation functions by an as yet completely unknown mechanism. Its genome contains none of the genes known for the synthesis of compatible solutes in other well- studied cyanobacteria like Synechocystis 6803, or marine Prochlorococcus and Synechococcus. We used SOLEXA technology to sequence the full transcriptomes of T. erythraeum cultures acclimated to three different salinities, 30, 37, and 43 PSU. We used two methods for library preparation: with differential RNA-sequencing, only newly synthesized RNAs (5’PPP) were sequenced, whereas full RNA-sequencing provided the coverage over expressed genes and operons. This approach allowed us to identify differentially expressed genes during salt acclimation, map the exact transcription start sites (TSS), and find previously unknown ncRNAs. We found over 5000 active, mapped TSS, roughly half of them yielding ncRNA transcripts. Around 20 % of all TSS were significantly differentially expressed under the tested salinities. Amongst them, a highly expressed repeated sequence without any related sequences in other bacteria was found and expression verified by Northern Blot hybridization. Target predictions indicate that it might serve as a suppressor of transposase activity. We also identified novel group II-introns, both with and without a self-encoded reverse transcriptase-maturase gene. Interestingly, we also found a change in the expression of nitrogen fixation (nif) cluster genes dependent on salinity. This is unexpected and further investigations will follow. This comprehensive data set will be highly valuable for the design of future experiments, in the lab and in the field.

299 MONDAY 9 SEPTEMBER 2013, 17:30 PS-7. What omics can (and can't) tell us about microbial ecology

PS-7.08. VIRAL COMMUNITY COMPOSITION IN DEEP AQUIFER ECOSYSTEMS

Renee Smith, Flinders University, Adelaide (Australia) Coauthors: Jeffries TC, Roudnew B, Seymour JR, Fitch AJ, Simons KL, Speck PG, Newton K, Brown MH, Mitchell JG

Pathogenic viruses in freshwater reserves represent a global health risk. However, knowledge about their diversity and abundance in deep groundwater reserves is limited. We found that the viral community inhabiting a deep confined aquifer in South Australia was more similar to reclaimed water communities than to the viral communities in the overlying unconfined aquifer community. This similarity was driven by high relative occurrence of the ssDNA viral groups Circoviridae, Geminiviridae, and Microviridae, which include many known plant and animal pathogens.These groups were present in 1500 year-old water situated 80 m below the surface, which suggests the potential for long-term survival and spread of potentially pathogenic viruses in deep, confined groundwater. Obtaining a broader understanding of potentially pathogenic viral communities within aquifers is particularly important given the ability of viruses to spread within groundwater ecosystems.

300 MONDAY 9 SEPTEMBER 2013, 17:30 PS-7. What omics can (and can't) tell us about microbial ecology

PS-7.09. DIVERSITY OF MICROORGANISMS ASSOCIATED TO AGLAOPHENIA OCTODONTA IN A BENEFICIAL CONSORTIUM

Loredana Stabili, University of Salento, DiSTeBA, Lecce (Italy) Coauthors: Gravili C, Boero F, Tredici M, Lezzi M, Pizzolante G, Alifano P

Diverse groups of eukaryotic and prokaryotic marine microorganisms rapidly colonize both non living and living submerged surfaces, including many invertebrates with outer skeleton. Motile and sessile microorganisms use colonial hydroids covered with chitinous perisarc for permanent or temporary attachment. Several papers describe the epibiotic community of somel Mediterranean colonial hydroids, analysing the spatial and temporal distribution of both diatoms and bacteria. In a previous study we observed an unknown association between the hydroid Aglaophenia octodonta (Cnidaria, Hydrozoa) and the luminous bacterium Vibrio sp. AO1. In the present work we describe the diversity of other microorganisms associated to this hydroid. Epifluorescence, optical and scanning electron microscopy observations evidenced the presence of microorganisms, whereas 16s rDNA gene sequencing and taxon specific primers for the 18s rDNA were employed to identify the various microorganisms. All the specimens of A. octodonta observed under blue light excitation showed a clear green fluorescence on the external side of the perisarc (chitinous exoskeleton) around hydrocladia due to Vibrio sp. AO1 and a red fluorescence due to the presence of microalgae. Moreover, under optical and scanning electron microscopy the presence of peritrich ciliates attached to the hydrothecal rims in number of about 4-5 per thecae was observed. Molecular analysis confirmed the presence of Vibrio sp. AO1 associated to A. octodonta. Morever, by the molecular sequencing the microalgae were assigned to Symbiodinum sp. AO1 belonging to the Clade A and the peritrich ciliates assigned to Pseudovorticella sp. AO1. Treatment of A. octodonta with the antibiotic ampicillin results in a decrease of vibrios luminescence followed by a Symbiodinium expulsion and Pseudovorticella detachment suggesting an involvement of all these microorganisms in a A. octodonta consortium with beneficial effects for the components. Further studies will be accomplished to better understand the role of each component in such an association.

301 THURSDAY 12 SEPTEMBER 2013, 17:30 PS-8. Bacterial biogeography and dispersal in a changing world

PS-8.01. EVALUATION OF BACTERIAL DIVERSITY IN SURFACE AND DEEP WATERS

Marta Antonioli, Dept. of Life Sciences, University of Trieste (Italy) Coauthors: Zoccarato L, Pallavicini A, Fonda Umani S

Estimating prokaryote diversity in natural ecosystems is a priority in current ecological research. Spatial and temporal patterns of microbial diversity are obscure, and especially in aquatic systems even less is known on the relationship between microbial diversity and ecosystem functioning. Distance, latitudinal gradients and environmental factors were demonstrated to influence bacterial community composition in lakes and in the ocean. Recent observations evidenced both cosmopolitanism (i.e. global occurrence) and conversely provincialism (i.e. geographically localized occurrence) for some microbial species and showed that bacterial community composition clustered according to the water masses. Salinity, temperature and consequently density act as potential oceanographic barriers separating water masses and their inhabiting bacterial communities. Free-living prokaryotes might be trapped in these distinct water masses leading to water mass-specific prokaryotic community composition and activity. The main aim of the study was to investigate bacterial diversity in samples collected in different marine areas from surface and deep waters in order to detect differences/similarities between sites and possibly identify common environmental factors controlling microbial community diversity. Quantitative analysis was performed through epifluorescence microscope, while bacterial diversity was evaluated with ARISA, a fingerprinting technique that relies on the high variability of the region between the genes encoding for 16S and 23S rRNA. Rank-abundant curves confirmed one of the most familiar patterns in biodiversity research, which implies that in microbial communities only a few phylotypes are dominant, whereas most are rare. Surface bacterial assemblages presented higher values of OTU richness and Shannon index compared to deeper ones, whereas evenness values were similar among all stations. Cluster analysis conducted via UPGMA algorithm produced similar results considering similarity indices based upon only presence/absence of identical OTUs and indices that evaluated also OTUs relative abundance. Dendrograms showed that surface stations grouped together and were separated from deeper stations. Within these two groups, communities clustering reflected the distance between sampling sites, confirming the geographic patterns of species diversity.

302 THURSDAY 12 SEPTEMBER 2013, 17:30 PS-8. Bacterial biogeography and dispersal in a changing world

PS-8.02. SPATIAL PATTERNS OF MICROBIAL BIOFILM BIODIVERSITY IN STREAMS

Katharina Besemer, WasserCluster Lunz (Austria) Coauthors: Singer G, Quince C, Chifflard P, Bertuzzo E, Wilhelm L, Wagner K, Battin T

Streams and rivers form dendritic landscapes, thereby creating the spatial template for biodiversity patterns. Ecological theory predicts headwaters to be relatively species-poor, therefore contributing little to system-wide biodiversity, which has been supported by studies on fish and invertebrates. However, these smallest components of a fluvial network are also the most abundant and have been shown to exhibit high levels of beta diversity. It remains yet unknown whether the dendritic geometry of fluvial networks constrains the distributional patterns of microbial diversity similar to that of larger organisms. Benthic biofilms dominate microbial life in streams and are the engines of major stream ecosystem processes. We studied microbial diversity of biofilms from 114 sites within an alpine catchment using 454 pyrosequencing of the 16S rRNA gene. Surprisingly, we found decreasing alpha diversity and evenness from headwaters downstream. We suggest that headwaters, intimately linked to the surrounding terrestrial environment, collect large numbers of microbial taxa of terrestrial origin, while the biofilm communities of larger streams might be dominated by a lower and more constrained number of “typical” stream biofilm species. In support of this, the relative importance of core versus satellite species increased in downstream direction. Biological interactions might further contribute to the observed patterns, as indicated by a strong negative correlation between overall biofilm diversity and the relative abundance of cyanobacteria in these biofilms. In accordance with our expectations, we found that headwaters exhibited the highest level of beta diversity in this stream network. Earlier studies on invertebrates and fish showed that the uniqueness of headwater communities renders them crucial for the maintenance of network-wide biodiversity. Our study underlines this notion by showing that, for microbial biofilms, headwaters contain the highest levels of both alpha and beta diversity in a stream network.

303 THURSDAY 12 SEPTEMBER 2013, 17:30 PS-8. Bacterial biogeography and dispersal in a changing world

PS-8.03. DISTRIBUTION AND ABUNDANCE OF CLUSTERS OF THE ROSEOBACTER CLADE IN THE NORTH SEA

Sara Billerbeck, University of Oldenburg, Institute for Chemistry and Biology of the Marine Environment (ICBM) (Germany) Coauthors: Bernd W, Giebel HA, Rolf D, Simon M

The Roseobacter clade is a group of Alphaproteobacteria that can account for large proportions of total Bacteria in diverse marine ecosystems. Most of the Roseobacter clusters identified in pelagic environments consist predominantly of uncultured phylotypes and only scarce information exists on the distribution of distinct subclusters. In order to elucidate the occurrence of major pelagic subclusters of the Roseobacter clade in coastal waters we analysed water samples from a transect across the North Sea from Germany to Norway collected in July 2011. We differentiated between the particle-associated (PA, >5 µm) and the free-living (FL, 0.2-5 µm) bacterial fraction and analysed the DNA extracted from polycarbonate filters by PCR with primers specific for the cluster RCA, NAC11-6, NAC11-7 and CHAB-I-5. To further validate the abundance of these Roseobacter clusters we applied pyrosequencing of the 16S rRNA gene to selected samples. In addition, parameters such as inorganic nutrients (phosphate, nitrate, nitrite), dissolved amino acids, chlorophyll a, bacterial cell numbers, biomass production and turnover rates of amino acids and glucose were assessed to better understand the biogeochemical and environmental conditions for the occurrence of these clusters. All four subclusters were detected in the investigated area but predominantly in the FL bacterial fraction. Together, they constitute up to 40% of the bacterial community in surface waters and show the same or even a higher abundance on the 16S rRNA gene level of the active bacterial fraction. The composition of the bacterioplankton and especially of the Roseobacter subclusters changes along the transect from the German Bight to the Norwegian Channel.

304 THURSDAY 12 SEPTEMBER 2013, 17:30 PS-8. Bacterial biogeography and dispersal in a changing world

PS-8.04. EFFECTS OF CONSUMERS ON MICROBIAL AND PHYTOPLANKTON DIVERSITY IN AQUATIC METACOMMUNITIES

Julia Birtel, EAWAG, Aquatic Ecology Department, Center for Ecology, Evolution and Biogeochemistry, Kastanienbaum (Switzerland) Coauthors: Matthews B

We conducted a large-scale outdoor mesocosms experiment in 2011 in order to investigate how Daphnia predation, as well as the initial abundance of microbial cells (in our study: dilution) affects phylogenetic diversity and species composition of bacteria and phytoplankton in aquatic metacommunities. Metacommunities are defined as local communities connected via dispersal. The role of space and environment for microbial community composition and diversity has been investigated repeatedly within lake surveys in various regions of the world. However, lake surveys are only able to explain a small fraction of the total variation in differences between communities and they vary in methodology and conclusions. In order to better understand which factors are driving community changes we have conducted this outdoor mesocosm experiment, which allowed us to selectively manipulate certain parts of the environment, while other environmental factors could be governed by natural variation. The large volumes used in our experiment allow us to draw direct comparisons to natural ecosystems.

305 THURSDAY 12 SEPTEMBER 2013, 17:30 PS-8. Bacterial biogeography and dispersal in a changing world

PS-8.05. MICROBIAL DIVERSITY OF COASTAL MICROBIAL MATS

Henk Bolhuis, Royal Netherlands Institute for Sea Research Yerseke (The Netherlands) Coauthors: Fillinger L, Stal LJ

The North Sea coast of the Dutch barrier island of Schiermonnikoog is covered by microbial mats that initiated the development of a densely vegetated salt marsh. Microbial mats consist of a simple layered structure of vertically stratified diverse microbial communities. Diatoms and Cyanobacteria enrich the sediment with organic matter through oxygenic photosynthesis driven primary production. Many Cyanobacteria can also fix nitrogen, by which they fertilize the beach sand with combined nitrogen. The North Sea beach has a natural elevation running from the low water mark to the dunes producing a gradient of several environmental factors perpendicular to the beach. This gradient is the result of the input of seawater at the low water mark and of freshwater from upwelling groundwater and rainfall at the dunes. This causes a natural and dynamic salinity gradient depending on the tides, rainfall and wind. Here we aimed at determining the community composition of representatives from each Domain of life (Bacteria, Archaea and micro-eukaryotes) and in particular of Cyanobacteria along this natural salinity gradient using denaturing gradient gel electrophoresis of rRNA gene fragments in combination with pigment analysis. In addition we studied the diversity of different mat types in detail by high throughput 454 sequencing of the 16S rRNA V6 region. Cluster analysis of the prokaryote and micro-eukaryote community fingerprints indicated the presence of three distinct mat types but with micro- heterogeneity between the samples. We also found a high diversity within both the bacterial an archaeal community. In addition to the visible dominant group of Cyanobacteria, we found high numbers of Proteobacteria and Bacteriodetes. Members belonging to the Actinobacterial phylum are also present high numbers in all mat types that together with the Cyanobacteria may form an interesting source of novel secondary metabolites of biotechnological and medical importance.

306 THURSDAY 12 SEPTEMBER 2013, 17:30 PS-8. Bacterial biogeography and dispersal in a changing world

PS-8.06. OCEAN ACIDIFICATION AND ITS EFFECT ON BACTERIAL EXTRACELLULAR ENZYMES

Tim Burrell, Victoria University of Wellington / National Institute of Water and Atmospheric Research Ltd, Wellington (Australia) Coauthors: Maas E, Teesdale-Spittle P, Law C

Heterotrophic bacteria are widely recognised as vital components in the cycling and regulation of organic material within the ocean. Limited research to date suggests that ocean acidification may influence bacterial extracellular enzyme hydrolysis rates. A significant increase in extracellular enzyme activity may accelerate the breakdown of labile high molecular-weight organic material and increase the availability of utilisable organic substrates in the surface ocean. Such a biological response to future ocean conditions may lead to strengthening of the microbial loop, ultimately resulting in a decrease in carbon export and long-term carbon sequestration. To examine this, I conducted a series of perturbation experiments during three NIWA research voyages in New Zealand waters during 2012. A range of interacting biological parameters were investigated under three oceanic treatments predicted for the end of the century; elevated seawater temperature (ambient +3°C), elevated pCO2 (750 ppmv; pH(T) 7.8), and “greenhouse” conditions (elevated temperature and pCO2), with responses compared with control samples maintained under ambient conditions. Treatment samples were analysed for bacterial numbers, bacterial biomass production, extracellular enzyme activity, dissolved organic carbon, chlorophyll-α, nutrients, glucose, and protein concentrations.

307 THURSDAY 12 SEPTEMBER 2013, 17:30 PS-8. Bacterial biogeography and dispersal in a changing world

PS-8.07. MARINE MICROBIAL POPULATIONS OF THE SOUTHWEST INDIAN OCEAN RIDGE SYSTEM

Anni Djurhuus, University of Oxford (UK) Coauthors: Rogers AD

Microorganisms account for most oceanic biomass, bacteria being the most abundant. They play a vital role in marine food webs and global nutrient and carbon cycling and are involved in virtually all geochemical reactions occurring in the sea. Seamounts often harbour elevated biomass and in low-chlorophyll environments, such as the deep sea; bacterial biomass becomes an important component of the total plankton biomass. Yet the microbial ecology around seamounts and ridges is not well understood. Microorganisms potentially contribute substantial amounts of organic matter to these ecosystems, and therefore detailed knowledge of the drivers of microbial abundance and dispersal is essential for the understanding of these ecosystems. We sampled at multiple depth horizons at four seamounts along the Southwest Indian Ridge, located in a frontal zone between sub-Antarctic and sub-tropical water. The study region covers marked differences in water column structure and therefore presents an opportunity to test the influence of water masses of contrasting temperature as well as the local oceanographic setting on microbial populations and biogeography. Sampling took place on regional scales (100s km), between different seamounts and watermasses as well as local scales (10s km), investigating the effects of individual seamounts on the microbial communities. Results from flow cytometry and elemental analysis, as well as environmental data provide evidence that microbial populations and their ambient environment are not homogenous throughout the Southwest Indian Ridge system. There is community turnover across the fronts with Prochlorococcus dominating the community in the north and heterotrophic bacteria dominating in the south. Instead of a clear break between the sub-Antarctic and the sub-tropical water masses microbial counts reflect three different sections of the study area. These sections indicate three different assemblages in three habitats: The north sub-tropical and south sub-Antarctic as well as the mixing zone in between. The mixing zone is not simply an intermediary between the north and the south but a whole distinct habitat, which may form a distinct biogeographic province. This has critical implications for understanding the impacts of climate changes on the trophic ecology and biogeochemistry of the oceans.

308 THURSDAY 12 SEPTEMBER 2013, 17:30 PS-8. Bacterial biogeography and dispersal in a changing world

PS-8.08. DIVERSITY OF BACTERIAL COMMUNITY IN MUSSELS FROM INDONESIAN MARINE LAKES

Rossana Freitas, CESAM, Universidade de Aveiro (Portugal) Coauthors: Cleary D, Polónia A, Becking L, Gomes N

Anchialine systems are small bodies of landlocked seawater and are thought to have been formed in the Holocene. Three types of anchialine systems can be distinguished in the Indo-Pacific based on different parameters bathymetry, size, degree of connection to the sea or coastline; these are: Marine lakes with large and deep basins; Anchialine pools with small and shallow basins; and Blue pools in chasms. The latter are little known and their flora and fauna have been barely documented. According to direct and indirect reports, the number of marine lakes is estimated at ~200, with lakes located in Croatia, Bermuda, Vietnam, Palau and Indonesia. The objective of the present study was to survey the mussel fauna of three marine lakes and one blue pool in a chasm in a karstic area (Berau, East Kalimantan) in Indonesia. We assessed bacterial richness and composition in mussels of the genus Brachidontes with the aim of trying to understand whether these symbotic associations differ from lake to lake. To this end, pyrosequencing of bacterial 16S rRNA genes was conducted. Populations inhabiting marine lakes provide an opportunity to study the early stagess of evolution in coastal marine taxa and high levels of differentiation in small populations such as in marine lakes can be due to combined effects of stochastic processes such as local adaptation and increased evolutionary rates. The present study contributed to a better knowledge of the diversity in these anchialine systems.

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PS-8.09. THE FRESHWATER SAR11 (LD12): ENVIRONMENTAL CONTROL OF ITS SEASONALITY, BIOGEOGRAPHY, AND PHYLOGENETIC DIVERGENCE

Friederike Heinrich, Uppsala University, Department of Ecology and Genetics (Sweden) Coauthors: Logue J, Logares R, Eiler A, Lindström E, Bertilsson S

The SAR11 group is ubiquitous in aquatic environments and often accounting for a large portion of the total bacteria in planktonic environments. In freshwater lakes, the clade is represented by the clade LD12, which can be considered as the sister group of the marine SAR11 clade. Here we investigate the environmental factors controlling LD12 at different temporal and spatial scales. We conducted a quantitative study of the seasonal dynamics of LD12 in a temperate lake (lake Erken, Sweden) using group-specific quantitative PCR (qPCR), catalyzed reporter deposition fluorescence in-situ hybridization (CARD-FISH), and 454 pyrosequencing of the 16S rRNA gene. We further investigated the potential drivers of biogeography and diversity of LD12 in 21 lakes from middle and northern Sweden using qPCR and 454 sequencing. In addition we did an inventory of public databases. Altogether, our results revealed a cosmopolitan distribution of LD12 and demonstrated that this clade can be as numerous in freshwater bacterioplankton as their marine SAR11 siblings. In addition, we observed a strong seasonality of LD12 in their contribution to the total bacterioplankton (2-40% of the total bacterial 16S rRNA pool) with pronounced peaks in both summer and late fall. The relative abundance of LD12 was lower during periods of high phytoplankton biomass and low availability of free inorganic nutrients. Thus, LD12 appear to thrive under conditions of high availability of inorganic nutrients and low phytoplankton biomass. Similar to the marine SAR11, local LD12 populations residing in different lakes appear to respond in contrasting ways to nutrient availability, implying either ecological divergence within the clade or variations in the interplay between environmental driver variables.

310 THURSDAY 12 SEPTEMBER 2013, 17:30 PS-8. Bacterial biogeography and dispersal in a changing world

PS-8.10. A GLOBAL SURVEY OF ACID MINE DRAINAGES MICROBIAL DIVERSITY REVEALS SPECIFIC ASSEMBLAGES AND NICHE CONSERVATISM

Fabien Javerliat, Université de Pau et des Pays de l'Adour - UMR CNRS-IPREM 5254 (France) Coauthors: Volant A, Laoudi S, Bruneel O, Fahy A, Casiot C, Iniguez V, Nieto JM, Duran R, Lauga B

Acid mine drainages (AMD) appear when minerals are exposed to air and precipitation, creating acidic streams with high metallic content, and is qualified as an extreme environment. The characteristics of AMDs make them good candidates to explore the geographic dispersion of micro-organisms because of their strong ecological constraints and their island-like repartition. We explore AMD microbial dispersal using 16S bar-code pyrosequencing, coupled with data mining. Twelve samples were collected from 3 mining regions across the world: Carnoulès in the Gard (France), the Iberian Pyrite Belt in Andalousia (Spain) and the Bolivian Altiplano. 120488 bacterial and archaeal high quality sequences with a minimum length of 430 bases were used in the analysis, allowing high sampling coverage as well taxonomic resolution. AMD microbial diversity is low compared to other mesophilic environments, which is expected in such extreme conditions, but inter-site diversity is high. Only two bacterial genera are shared among all drainages, Acidithiobacillus and Leptospirillum, and one archaeal genus, Ferroplasma. Few other genera dominate the AMD communities: Gallionella, Ferrovum and Thiobacillus (β-proteobacteria), Acidocella and Acidiphillium (α-proteobacteria), and an uncultured bacterium from the Xanthomonadaceae (γ-proteobacteria) are also very abundant. Those organisms are commonly encountered in other AMDs. Although they are not present in all sites from our study, each is dominant in at least one of the sites. Even though the studied drainages are acid, pyrite-rich environments, the physico-chemical parameters differ from site to site. Indeed we show that pH, 2- and Fe, SO4 , Al, Co, Sr, Rb concentrations are factors that explain inter-site diversity. Finally we conduct data mining in the public databases in order to obtain an insight of the global distribution of very close relatives of the organisms identified in our studies and we observed distinct patterns. In the case of OTUs present in 10 to 12 of the AMDs, more than 80% of their close relatives are also found in mine-impacted, acid or volcanic environments, 8% found in soils (mainly acidic) and 5% from freshwaters. In contrast, OTUs present in only 1 to 3 samples have relatives detected in more diverse environments: of those, mine-impacted, acid or volcanic environments represent only 23%, while soils represent 28%, and mammalian host associated organisms 16%. Those OTUs also have relatives more frequently encountered from sediment, freshwater, high salinity and hydrocarbon impacted environments. In conclusion, we are able to assess microbial community assemblages in AMDs and show that they are shaped by physico-chemical parameters within the AMD environments. We were able to pinpoint OTUs that show niche conservatism.

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PS-8.11. SPATIOTEMPORAL SUCCESSION OF DIFFERENT LINEAGES OF LIMNOHABITANS BACTERIA IN A CANYON-SHAPED RESERVOIR

Jan Jezbera, Biology Centre of ASCR v.v.i, Institute of Hydrobiology, České Budějovice (Czech Republic) Coauthors: Jezberova J, Znachor P, Nedoma J, Kasalický V, Simek K

Limnohabitans genus is nowadays widely accepted as one of the key members of freshwater Betaproteobacteria. Recently, designed Limnohabitans lineage-specific Reverse Line Blot Hybridization (RLBH) probes enabled to examine the spatiotemporal succession of distinct lineages affiliated with this genus in two independent studies: (i) during the intensive spring period sampling program at the lacustrine part of the Římov Reservoir (from ice melt through onset of a phytoplankton peak to the clear-water phase), and (ii) during the whole-year study when occurrence of distinct Limnohabitans lineages was related to inherent longitudinal heterogeneity of this canyon-shaped reservoir. Significant spatiotemporal changes in the composition of distinct Limnohabitans lineages have been recorded in both studies. We were able to identify ‘generalists’ Limnohabitans lineages that were always present throughout the whole season as well as ‘specialists’ that appeared in the reservoir only for short periods of time or irregularly. Several phytoplankton groups, such as Cryptophytes, were proposed to be potentially affecting the distribution and dynamics of distinct Limnohabitans lineages. Other parameters, such as pH, chl-A, and primary production were also found to be theoretically responsible for occurrence of different Limnohabitans lineages. Revealed diversity, in terms of Limnohabitans lineages recorded, changed downstream in the Římov Reservoir, with most significant differences found between the inflow and dam parts of the reservoir. Highest diversity of Limnohabitans lineages, recorded at the inflow part, hints on important influence of watershed on Limnohabitans microdiversity.

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PS-8.12. SPATIAL AND TEMPORAL VARIATION OF BACTERIOPLANKTON COMMUNITY COMPOSITION AND DIVERSITY IN THE GULF OF FINLAND (THE BALTIC SEA)

Peter Laas, Marine Systems Institute at Tallinn University of Technology, Tallinn (Estonia) Coauthors: Simm J, Lips I, Kisand V, Metsis M

Microbial communities are extremely diverse and highly dynamic, undergoing shifts in composition in response to spatial and temporal environmental gradients. The Gulf of Finland is the easternmost sub-basin of the Baltic Sea. It is directly connected, without a sill, to the Baltic Proper at its western end and to the Neva River’s mouth at its eastern end, thus having the highest annual fresh water inflow and anthropogenic influence of the sub-basins of the Baltic Sea. Water sampling aboard the RV Salme was performed during 7 cruises (from December 2010 to July 2011). Samples were collected from depths 5 m, 40 m and about 5 m above the seafloor along horizontal cross sections of the gulf. For metadata different physiochemical parameters were collected, including oxygen and inorganic nutrient concentrations. Water samples for microbial community analysis were filtered using closed system with 5.0 and 0.2 µm pore size filters. From whole community DNA samples the bacterial 16S rRNA gene V1-V2 hypervariable regions were PCR amplified. Sequencing of the amplicons was performed on Roche 454 platform. Reads with low quality and shorter than 150 bps were removed from the dataset. The PyroNoise algorithm was used to discard homopolymer-derived and PCR errors. OTUs (Operational Taxonomic Units) were defined using the average neighbor clustering algorithm of MOTHUR with 97% similarity threshold. We identified 3120 unique OTUs (1829 singeltons) with representatives from 31 different bacterial classes. 11.5% of the sequences remained unclassified. Most dominant OTUs belonged to following classes: α-proteobacteria (26%), Actinobacteria (15%), Epsilonproteobacteria (13%), Cyanobacteria (11%), β-proteobacteria (7%), Flavobacteria (6%), γ- proteobacteria (5%) and Sphingobacteria (1%). Most abundant OTUs throughout the sampling period and stations represented the SAR11 clade, classified as Candidatus Pelagibacter. Samples with hypoxic and anoxic conditions were inhabited mostly by Sulfurimonas phylotypes. Based on analysis of collected data we conclude that: (i) the community composition variance was greater in vertical space than in horizontal space or time; (ii) wintertime communities have equal or even higher diversity (according to Chao1 richness estimates) as compared to summertime communities; (iii) group of dominant OTUs were present throughout sampling period and groups of less abundant OTUs varied more sporadically.

313 THURSDAY 12 SEPTEMBER 2013, 17:30 PS-8. Bacterial biogeography and dispersal in a changing world

PS-8.13. IS EVERY STREAM AN ISLAND? DISTRIBUTION OF BACTERIAL COMMUNITIES IN DISTINCT TRIBUTARIES OF FRESHWATER STREAMS

Kelvin Lau, School of Biological Sciences, The University of Auckland (New Zealand) Coauthors: Washington V, Neale M, Lewis G

While it is clear that the biodiversity of macro-organisms exhibit distinct geographical distributions, it has long been assumed that micro-organisms are more ubiquitous and lack well defined biogeographic patterns- "Everything is everywhere, but the environment selects" (Baas- Becking, 1934). The objective of this study was to investigate the biogeography of stream biofilm bacterial communities on a fine scale so that the confounding effects of environmental selection can be minimised, and to determine whether bacterial communities exhibit a cosmopolitan distribution. The stream biofilm ecosystem provides an ideal model ecosystem in this respect. By taking samples from distinct tributaries that are in the same catchment area, we can minimise the impact of differences due to regional environmental factors. While multiple tributaries that lead into the same stream may be in close proximity, the unidirectional flow of water limits the migration of microorganisms upstream. The bacterial communities of biofilms collected from tributaries of four freshwater streams (24 sites) in Auckland, New Zealand were examined using Automated Ribosomal Intergenic Spacer Analysis (ARISA) and high throughput sequencing. Results suggest similar bacterial community profiles in distinct tributaries from the same catchment, while significant differences in community structure were observed in streams in neighbouring catchments. The study of biogeography can offer insights into the mechanisms that generate and maintain diversity, such as speciation, extinction, dispersal and species interactions in the stream ecosystem. A better understanding these factors will help to describe the dynamic spatial and temporal changes in the stream bacterial communities.

314 THURSDAY 12 SEPTEMBER 2013, 17:30 PS-8. Bacterial biogeography and dispersal in a changing world

PS-8.14. HIGH FREQUENCY SAMPLING REVEALS DETAILED TEMPORAL PATTERNS OF BACTERIOPLANKTON POPULATION DYNAMICS IN THE BALTIC SEA

Markus Lindh, Linnaeus University, Kalmar (Sweden) Coauthors: Andersson AF, Baltar F, Hugerth L, Legrand C, Lundin D, Nilsson E, Sjöstedt J, Pinhassi J

Studies investigating to what extent abundant and rare bacteria contribute to population dynamics, diversity and relatedness in bacterioplankton communities at different times of the year are sparse. To accurately understand these dynamics in a changing environment, it is necessary to assess the detailed development of different populations. Here we investigated temporal dynamics of bacterioplankton communities by high-frequency sampling (twice weekly) at the Linnaeus Microbial Observatory in the Baltic proper during 2011. 454 pyrosequencing of amplified 16S rRNA gene fragments (on average 2500 reads per sample) provided 3079 OTUs (at 97% 16S rDNA identity level). Analysis of OTU distributions by nMDS revealed a distinct clustering of samples into spring, summer and autumn communities. Over the year, phytoplankton community composition, temperature and nutrients contributed significantly to structuring bacterial communities. Nevertheless, detailed analyses of patterns of occurrence of the individual OTUs revealed intricate temporal dynamics. These included seemingly coordinated major temporal transitions in related populations, e.g. the increase in relative abundance of Alphaproteobacteria OTUs at the expense of Bacteriodetes OTUs between spring and summer, and the increase of Actinobacteria OTUs at the expense of Alphaproteobacteria between summer and autumn. Still, within each of these major taxa and even within abundant lineages like SAR11, SAR86 and Synechococcus sp. there was an unexpected, yet consistent variation in patterns of occurrence, indicating a differentiation into different ecotypes. Our analyses show that frequently detected bacteria in the Baltic Sea can be classified into: (i) resilient populations, abundant most of the year (10 OTUs), (ii) transient populations exiting and entering the abundant and rare biosphere (109 OTUs), (iii) neutral populations present most the year in low abundance (60 OTUs), and finally (iv) among transient populations there were opportunistic pulse populations, with only a single peak in relative abundance (16 OTUs). Interestingly, a verrucomicrobial OTU (Candidatus Spartobacterium baltica1) increased 10-fold in relative abundance shortly after the cyanobacterial bloom in summer. Surprisingly, a wind-driven upwelling event brought Sulforimonas sp. OTUs, typically associated with the chemocline, to complete dominance at the surface (68%). In conclusion, our study provides a framework for interpreting high-resolution time series for evaluating net rates of change in both abundant and rare lineages in the sea, in response to changing environmental conditions. Thus, providing an understanding of the relationship between bacterioplankton phylogeny and physiological capacity at different temporal scales.

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PS-8.15. SPATIAL AND TEMPORAL DYNAMICS OF THE BACTERIAL COMMUNITY IN THE GERMAN BIGHT

Judith Lucas, Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research, Helgoland (Germany) Coauthors: Wichels A, Gerdts G

Microbial abundance, diversity and variability in marine systems have been the focus of many studies during the past few decades. Although there is a growing understanding of bacterial community composition (BCC) and its temporal and spatial variability, the factors that drive changes within these structures are still not properly understood. Keeping in mind that conditions in the marine environment are influenced by a large-scale hydrographic regime, the Eulurian approach leads to difficulties in interpreting results. Thus it should be of great interest to assess both, spatial and temporal scales at the same time. The current study focuses on the diversity and variability of the BCC in the German Bight. In order to deconvolute temporal and spatial signals, water samples have been taken on monthly transects in the German Bight over a period of one year. Simultaneously samples have been taken at the sampling site “Kabeltonne” (54°11.3’N, 07°54.0’E) at Helgoland Roads on a weekly basis. Various physico-chemical parameters as well as biological parameters such as qualitative and quantitative data on phytoplankton and microorganisms have been recorded during sampling. To reveal seasonal and spatial patterns in bacterial variability, ARISA fingerprints were analysed using multivariate statistics. Additionally BCC will be analysed via 16S rRNA tag pyrosequencing. The results from the fingerprint analysis will be linked with physico-chemical and biological parameters and analysed in the context of hydrodynamic simulations.

316 THURSDAY 12 SEPTEMBER 2013, 17:30 PS-8. Bacterial biogeography and dispersal in a changing world

PS-8.16. NEUTRAL ASSEMBLY OF BENTHIC MICROALGAE IN INTERTIDAL SEDIMENTS

Craig Plante, College of Charleston (USA) Coauthors: Fleer V, Jones ML

Benthic microalgae provide vital food resources for heterotrophs and stabilize sediments with their extracellular secretions. Our objectives were to assess effects of sediment resuspension on microalgal community structure. We tested whether taxa-abundance distributions could be predicted using neutral community models (NCMs) and also specific hypotheses about passive migration: 1) As migration to sediment patches increases, variation in individual population sizes will decline, and 2) As migration increases, species diversity will increase. Also, co-occurrence indices were computed to test for deterministic factors, such as competition and niche differentiation, in shaping communities. Two intertidal sites (mudflat and sandflat) differing in resuspension regime were sampled throughout the tidal cycle. DGGE was utilized to investigate diatom community structure. Observed taxa-abundances fit those predicted from NCMs reasonably well (R2 of 0.68-0.88), whereas no co-occurrence tests indicated a significant role for competitive exclusion or niche partitioning in microalgal community assembly. In general, predictions about relationships between migration and species richness, diversity, and individual population variability were supported for local community dynamics. Benthic microalgae at low tide (lowest migration) exhibited reduced diversity as compared to high tide times, whereas variability for individual taxa was higher. In between-site metacommunity comparisons, low- and high-resuspension sites exhibited distinct community compositions while the low-energy mudflats contained higher microalgal biomass and greater species diversity.

317 THURSDAY 12 SEPTEMBER 2013, 17:30 PS-8. Bacterial biogeography and dispersal in a changing world

PS-8.17. MAP OF 3D DISTRIBUTION OF HYDROCARBONOCLASTIC BACTERIA IN MEDITERRANEAN SEA

Santina Santisi, Istituto per l'Ambiente MArino Costiero (IAMC – CNR), Messina (Italy) Coauthors: Messina E, Yakimov MM, Genovese L, Mazzola S, Dibidetto M, Quatrini P, Catania V, Cappello S

The obligate hydrocarbonoclastic bacteria (OHCB) has been recognized and shown to play a significant role in the biological removal of hydrocarbons from polluted marine waters. The introduction of oil or hydrocarbons into seawater leads to successive blooms of a relatively limited number of indigenous marine bacterial genera (Alcanivorax, Marinobacter, Thallassolituus, Cycloclasticus and Oleispira) which are present at low or undetectable levels before the polluting event. The types of OHCB that bloom depend directly from level and type of pollution and from parameters as the latitude/temperature, salinity, redox etc.... In this work, using data present in GeneBank we have create a virtual map of 3D distribution of OHCB in Mediterranean Sea according to physical-chemical factors.

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PS-8.18. IMPACT OF FRESHWATER INFLOW ON BACTERIAL ABUNDANCE AND ACTIVITY IN THE ESTUARINE SYSTEM RIA DE AVEIRO

Luísa Santos, Department of Biology & CESAM, University of Aveiro (Portugal) Coauthors: Vaz L, Marcial Gomes NC, Vaz N, Dias JM, Cunha A, Almeida A

The influence of freshwater flow on bacterial abundance and activity in the estuarine system Ria de Aveiro (Portugal) was investigated in two sites differently impact by river inputs and considered representative of the marine (MZ) and brackish water (BZ) zones of the estuary. Sampling events, performed every two months during two-years, were clustered based on hydrological features. The hydrodynamic was simulated with a Lagrangian model and related with microbiological parameters. Estuarine bacterial communities responded to different freshwater regimes developing distinct patterns of abundance and activity at the MZ and BZ. A circulation pattern induced by high river inflow produced vertical stratification at the MZ, promoting a landward flux of phytoplankton and seaward flux of bacterioplankton, and stimulating the import of riverine phytoplankton and particle-attached bacteria to the BZ. Advective transport and resuspension processes contributed to a 3-times increase of the abundance of particle-attached bacteria during intense freshwater inputs. Additionally, bacterial activity in the estuary was controlled by nitrogen concentration, responding to different freshwater inputs, which, in association with different prevailing sources of organic substrates induce significant changes in bacterial production. The dynamics and main controlling factors of bacterial communities in the estuary are clearly impacted by freshwater inputs. Therefore, significant changes on recycle of organic and inorganic nutrients by estuarine microbial activities can be expected from alterations in freshwater inputs either related to global climate change or to regional hydrological regimes.

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PS-8.19. BACTERIAL COMMUNITY COMPOSITION IN MARINE BIOAEROSOLS

Jasmin Seifried, Alfred Wegener Institute, Helgoland (Germany) Coauthors: Wichels A, Gerdts G

Dynamics and impact of marine bioaerosols are still poorly understood. The sojourn time of airborne microorganisms can last to several days, so even transcontinental transport is likely to occur. Only little is known about bacterial communities of marine bioaerosol in terms of diversity community composition. Few recent studies showed that bioaerosols often exhibited a similar bacterial community as the subjacent ecosystems. We combined two different sampling strategies in our recent investigation. In order to elucidate the spatial variation, 36 samples were gathered during a ship cruise from the North Sea to the Baltic Sea in August 2011 using an impingement sampler (XMX/2L-MIL, Dycor, Canada). Furthermore, a one year survey is conducted to investigate temporal variation of bioaerosols at the offshore island Helgoland (German Bight, North Sea). The samples were analyzed with culture independent molecular methods. Quantification was carried out using q-PCR and C-FLAPS analysis. The community structure was analyzed with ARISA- fingerprints. Phylogenetic analysis was performed via 454 16S tag-sequencing. First results showed high variation in spatial distributions, concerning the concentration of airborne bacteria, ranging from 10² to 105 cells per m-³. This is probably explained by the origin of sampled air parcels, correlated to the calculated backward trajectories, which also showed high variation. These results will be integrated within the context of the 454 sequencing data. Furthermore, results of the temporal aspect will be shown for the first time.

320 THURSDAY 12 SEPTEMBER 2013, 17:30 PS-8. Bacterial biogeography and dispersal in a changing world

PS-8.20. DYNAMICS OF FREE-LIVING AND PARTICLE-ASSOCIATED SAR11 BACTERIA IN SURFACE WATER OF THE PACIFIC OCEAN

Shotaro Suzuki, Atmosphere and Ocean Research Institute, University of Tokyo (Japan) Coauthors: Kaneko R, Kodama T, Hashihama F, Suwa S, Tanita I, Furuya K, Hamasaki K

Members of the a-proteobacterial SAR11 clade are the most abundant group in seawater environment and thus play important roles in the ocean’s food web and biogeochemical cycles. The SAR11 clade consists of some subclades or presumably ecotypes, however spaciotemporal dynamics and environmental adaptation of these subtypes are not fully understood especially in the Pacific Ocean. The aim of this study was to determine habitat preference of SAR11 subtypes comparing their spatial distribution between two lifestyles (free-living vs. particle-associated) and among different water masses in the tropical and subtropical Pacific. During the cruise of R/V Hakuho-maru from December 2011 to March 2012, surface seawater samples from nine stations in the North Pacific subtropical gyre (NPSG), South Pacific subtropical gyre (SPSG) and equatorial region (EQ) were collected and serially filtered through 3 and 0.22 um pore-size membranes to have particle-associated and free-living bacteria, respectively. Profiles of a whole bacterial community obtained by means of PCR-denaturing gradient gel electrophoresis (DGGE) targeting the 16S rRNA gene showed distinctive community structures among three water masses (NPSG, SPSG and EQ). Clone library construction and sequencing of 16S rRNA genes showed the presence of several subtypes of SAR11 bacteria in our study area, where subgroup-1b, -1a and -2 were the major subtypes. They were more abundant in free-living assemblages than in particle-associated ones. We also measured relative abundance of each subgroup by deeply sequencing the V1-V2 region (c.a. 3500-15000 reads) and found distribution patterns of the SAR11 subgroups. The subgroup-1a was more abundant in the EQ than in other regions whereas the subgroup-1b was more in the NPSG and SPSG than in the EQ, suggesting the level of nutrient and primary productivity partition their niches. In this study, we have revealed relative abundance of SAR11 bacteria in surface water of the tropical and subtropical Pacific with their preferential occurrence in the free-living assemblages and possible niche partitioning of the SAR11 subclades by oligotrophy.

321 THURSDAY 12 SEPTEMBER 2013, 17:30 PS-8. Bacterial biogeography and dispersal in a changing world

PS-8.21. COMPARISON OF A BIOCHEMICAL TEST SYSTEM WITH MASS SPECTROMETRY FOR IDENTIFICATION OF BACTERIA PERTINENT TO A FRESHWATER STREAM ENVIRONMENT

Natalija Topić Popović N, Rudjer Boskovic Institute, Zagreb (Croatia) Coauthors: Sauerborn Klobucar R, Maguire I, Strunjak-Perović I, Kazazić S, Barisić J, Jadan M, Klobucar G, Coz-Rakovac R

The amphipod Gammarus fossarum, stone crayfish Austropotamobius torrentium, an aquatic prosobranch gastropod mollusk Bithynia tentaculata, water from a pristine stream of the Nature Park Medvednica (Croatia), as well as scrapings from the sedimentary rocks, were sampled for microbiological evaluation. Rapid identification of environmental bacteria via commercial phenotypic tests allows for a wide choice of tests selection, and API 20E, an identification system for Enterobacteriaceae and other non-fastidious Gram-negative rods developed for clinical specimens, seems to be increasingly used for the identification of water-borne pathogens. However, due to several shortcomings of this system, such as the wrong identifications and the need of comparison with the diagnostic schemes based on reactions in conventional phenotypic tests, more advanced methods for identification are sought after. Therefore, a mass spectrometry MS-based method that focuses on the ribosomal proteins as a proteotypic system to utilize MALDI-TOF was used to achieve a highly accurate identification based on molecules that are translated from DNA but not subject to the expression variability seen in phenotypic methods. An excellent accordance of 57% was observed between the two methods in identification to the genus (Pseudomonas, Aeromonas, Shewanella spp.), while no correspondence was noted in identification to the species. Although this study furnished more accurate information on the bacterial populations in a surveyed freshwater stream (prevalence of Aeromonas and Pseudomonas spp.), and better clarified the existing relationships between the bacterial flora in tested samples, even a high-precision system had difficulties distinguishing between the species of the genus. Therefore, although implementation of MALDI-TOF MS can be a first step for identification which shortens the turnaround time, other methods for rapid analysis are warranted in order to obtain comparison of data and achieve an unambiguous identification.

322 THURSDAY 12 SEPTEMBER 2013, 17:30 PS-9. Microbial metabolic specialization: causes and ecological consequences

PS-9.01. DIVERSITY OF AROMATIC CATABOLIC GENES IN RESPONSE TO TEMPERATURE CHANGE IN LAKE SEDIMENTS

Ahmed Abdel Hafez Sayed Osman Ahmed, Department of Ecology and Genetics, Limnology, Uppsala (Sweden) Coauthors: Gudaz C, Bertilsson S

Pathways for the biodegradation of aromatic compounds are diverse, but they usually involve the formation of common intermediates such catechol and benzoyl-CoA. In this study, we assessed the diversity of catechol 2, 3 dioxygenase (C23O) and benzylsuccinate synthase (BssA) genes in bacteria responding to temperature change, depth and dissolved organic matter in two Swedish lake sediments; humic Lake Svarttjärn and eutrophic Lake Vallentunasjön. Sediment cores were incubated at temperature ranged from 1.0- 21.0 ºC and 4 depths were studied. Several molecular techniques were conducted such as cloning, t-RFLP and qPCR. The composition of bacteria featuring catechol 2, 3 dioxygenase genes differed both between and within sediments from each lake. C23O gene copy number was positively correlated to temperature in Vallentunasjön where sediments incubated at the highest temperature featured particularly distinct communities of bacteria carrying C23O genes. Catechol 2, 3 dioxygenase genes were presently in much lower concentrations in Svarttjärn. In contrast, BssA genes were only detected in Svarttjärn with highest abundance at low temperature (1.0-8.0 ºC). The studied catabolic genes were typically most abundant in the top 2 cm of the sediment. Measured respiration agreed with the abundance of the microbial communities possessing catechol 2, 3 dioxygenase gene and benzylsuccinate synthase genes. These results imply a coupled positive impact of temperature on combined microbial respiration and the potential to use a specific recalcitrant subset of the total DOC pool, aromatic compounds, to fuel the resident microorganisms. Understanding the response of catabolic pathways and degradation mechanisms and key enzymes will enable us to forecast how critical ecosystem services, such as degradation of aromatic compounds, will respond to future environmental change.

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THURSDAY 12 SEPTEMBER 2013, 17:30 PS-9. Microbial metabolic specialization: causes and ecological consequences

PS-9.02. REDUCTIVE DECHLORINATING MICROBIOMES IN CONTAMINATED SEAWATER SEDIMENTS AND GROUNDWATERS

Sara Borin, University of Milan, Department of Food, Nutritional and Environmental Sciences (Italy) Coauthors: Merlino G, Mapelli F, Lavazza D, Barbato M, Carpani G, deFerra F, Vitale E, Daffonchio D

Halogenated organic compounds are extensively used in industry and agriculture and are, as a consequence, common contaminants in waters and sediments. Organohalide-respiring bacteria, capable of deriving energy for growth from dehalogenation, belong to several phyla, including Proteobacteria, Firmicutes and Chloroflexi. Reductive dehalogenation has been demonstrated to be a key microbial metabolism for groundwater remediation, and dehalogenase homologous genes have been retrieved both in contaminated groundwater and seawater environments. Aim of this work was to study and compare the phylogenetic and functional diversity of the reductive dechlorinating microbiota in groundwater and seawater sediments from sites with a different contamination context. Sediment slurry microcosms have been set up and spiked with known amounts of 1, 2-dichloro ethane (1, 2-DCA) as electron acceptor and different sources as electron donors. A series of subsequent culture transfers, where the dehalogenating consortia were inoculated in fresh media supplemented with 1, 2-DCA and the proper electron donor, were established with the aim of selecting the best adapted bacterial consortium. Bacterial phylogenetic diversity was monitored by 16S rRNA gene-based PCR-Denaturing Gradient Gel Electrophoresis (DGGE) and barcoded pyrosequencing, while the functional diversity was described by DGGE fingerprinting on conserved domains of the dehalogenase encoding genes. The results indicated that both groundwater and seawater examined have dehalogenating potentials for remediation, showing complete degradation of 1, 2-DCA in anaerobic microcosms and the enrichment of different dehalogenase-homologous encoding genes characterized by sequence domains specifically associated to 1, 2-DCA metabolism. Despite a conserved 1, 2-DCA reductive dechlorinating potential, the different environments and contamination context lead to the selection of specific communities with functional and phylogenetic diversity adapted to the peculiar geo-chemical settings.

324 THURSDAY 12 SEPTEMBER 2013, 17:30 PS-9. Microbial metabolic specialization: causes and ecological consequences

PS-9.03. ADAPTATIONS TO SEMI-SYNTHETIC ANTIBIOTICS DRIVE DRASTIC CHANGES IN AQUATIC BACTERIAL COMMUNITIES

Gianluca Corno, CNR-ISE, Verbania (Italy) Coauthors: Giardina M, Plechuk S, Coci M, Campanile F, Stefani S

The spread of resistances to commonly used synthetic antibiotics (AB) in natural environments is one of the major threats to human health. A large number of publications investigated the relations between different human pathogens and the spread of AB resistances, but a comparably low number of studies targeted the ecological effect of the presence of synthetic AB on non- pathogenic bacteria in waters. We tested the long-term impact of a cocktail of synthetic antibiotics of commercial use (Imipenem, Levofloaxcin, and Tetracycline) on artificial bacterial communities miming a very simplified natural freshwater community. The experimental setup consisted in a 24 days-long continuous culture system where the bacterial communities were exposed to three different AB concentrations: no AB (control), sub-lethal AB concentration (comparable to anthropized European lakes), and in AB concentration 10 folds higher (comparable to heavily contaminated water treatment plants). Bacterial number and morphological distribution were daily monitored (epifluorescence microscopy), while community composition (CARD-FISH) and antibiotic resistance were assessed bi-weekly. Bacterial production, and thus abundance, dropped by 75% in the presence of AB, independently by their concentration, while bacterial community composition resulted highly affected by intermediate AB concentration, with reversal in the proportion of the dominant groups (Aeromonas hydrophila and Brevundimonas sp.). These results, for the first time focussing on the ecological consequences of AB on a experimental bacterial community, highlight the potential risk posed by low AB concentrations in waters. Their effect is not only limited to the spread of potentially pathogenic strains, but it extends to modification of interspecific ecological interactions, weakening the natural resistance of the aquatic communities to the success of allochtonous, and potentially dangerous, strains.

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PS-9.04. RHIZOSPHERE-COMPETENT PLANT GROWTH-PROMOTING BACTERIA ENHANCE GROWTH OF SEEDLINGS OF THE MANGROVE AVICENNIA MARINA

Khaled El-Tarabily, United Arab Emirates University (United Arab Emirates) Coauthors: Youssef T

This study was aimed at isolating and identifying rhizosphere-competent plant growth promoting bacteria (PGPB) from the mangrove Avicennia marina rhizosphere and at evaluating their potential as biological inoculants to promote the growth of mangrove seedlings in afforestation programs in the United Arab Emirates (UAE). Sixty-two different bacterial isolates were screened initially for their ability to colonize mangrove roots in vitro and to be rhizosphere-competent under a naturally competitive environment. Nine promising rhizosphere-competent isolates were subsequently evaluated for their ability to produce in vitro plant growth regulators (PGRs) (auxins, gibberellic acid, cytokinins and polyamines), 1-aminocyclopropane-1-carboxylic acid (ACC) deaminase, siderophores, HCN and ammonia. Three rhizosphere-competent isolates namely, Halobacillus trueperi, Marinobacter lipolyticus and Pseudoalteromonas maricaloris were selected based on their superior abilities to produce PGRs and ACC deaminase. Greenhouse experiments were conducted to investigate the effects of these three isolates, individually and in combination on mangrove seedlings growth, photosynthetic gas exchange and endogenous levels of some PGRs in both roots and shoots. The combination of the three isolates resulted in levels of plant growth promotion, superior to those that were exposed to individual strains. This was evident from the significant (P<0.05) increases in the levels of photosynthetic pigments, in planta auxins (indole-3- acetic acid and indole-3-pyruvic acid), polyamines (putrescine, spermidine and spermine) and the significant (P<0.05) reduction of the endogenous levels of ACC, the immediate precursor of ethylene, in roots and shoots compared with control plants or plants grown in sediments inoculated with only individual strains. The maximal Rubisco-catalyzed carboxylation velocity (Vc, max) increased by more than four -fold in plants treated with the mixture of the three bacteria over the control. These three isolates are considered to have the potential to perform as plant growth promoters for mangrove production in nutrient impoverished soils in arid coastal areas. This study is the first to demonstrate the potential of indole-3-pyruvic acid, polyamine and ACC deaminase producing rhizosphere-competent PGPB to promote mangrove growth under greenhouse conditions.

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PS-9.05. SPATIAL AND TEMPORAL HETEROGENEITY OF SEDIMENT MICROBIAL FUNCTIONING IN A MEDITERRANEAN RIVER

Anna Freixa, University of Girona (Spain) Coauthors: Ejarque E, Guarch Ribot A, Amalfitano S, Fazi S, Butturini A, Romaní AM

Heterotrophic microorganisms play a key role in aquatic ecosystem organic matter decomposition and nutrient cycling. Changes in the microbial metabolic activity of bacterial communities along the river can affect the organic matter quality and vice versa. The main objective of this study was to determine the spatial and temporal variation of microbial functioning and structure in river sediments. Thirteen sites along the River la Tordera (Nord East of Iberian Peninsula) were selected and analysed at two hydrological distinct periods (spring and summer). Sediment microbial activity was estimated by measuring the extracellular enzymes, respiration, and functional diversity by using Biolog Ecoplates. Moreover, the microbial abundance, organic matter and chlorophyll-a concentration were evaluated in all collected sediments. Spatial and temporal significant differences were observed in microbial sediment functioning. Polysaccharide decomposition (β- glucosidase and β-xylosidase) were enhanced in spring while decomposition of peptides (leucine aminopeptidase) and a higher concentration of chlorophyll-a were measured in summer. Significant higher potential metabolic capacity (Average Well Colour Development, AWCD after analysis of Biolog Ecoplates) was detected in summer. Functional diversity (Shannon index) decreased in spring in downstream sites. The headwaters sediment was characterized by higher degradation capacity of cellulose and hemicellulose linked to a greater input of allochthonous material. In contrast, an increase of recalcitrant organic matter use (decrease in the ratio of β- glucosidase:phenol oxidase activity) was observed downstream. The coefficient of variability between sampling sites for most of the parameters measured was higher in summer than in spring suggesting that low discharge periods provide a higher heterogeneity of the streambed sediment microhabitats. Although differences between sites was not equal for both periods, there was a clear separation between headwaters and lower parts and some specific sites defined as hotspots were maintained independent to temporal changes.

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PS-9.06. MANGANESE AND IRON SEQUESTERING BACTERIAL IN MARINE ENVIRONMENTS

Mikal Heldal, Department of Biology, University of Bergen (Norway) Coauthors: Erichsen ES, Radeke S, Bratbak G

Iron and manganese sequestering bacteria have been recorded in coastal waters of Norway and in the Spitsbergen area through an annual cycle. The bacteria are identified by morphology and X-ray microanalyses in SEM/TEM. Manganese and iron are bound in external structures of organic matrix which form various structures. The most common species consist of a central cell surrounded by a manganese/iron encrusted ring. The zone between the cell and the outside ring seem to be a thin organic film. Other species have star like structures or organic filaments of metal encrusted organic material. Other metal encrusted structures of possibly microbial origin are also identified in this material. The aim of these studies are to identify the taxonomic affiliation of these bacteria and reveal their ecological significance, since these organisms seems overlooked in most work related to elemental cycling of iron and manganese in marine environments.

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PS-9.07. A NOVEL PROTOCOL FOR EFFICIENT ANALYSES OF FREE NEUTRAL CARBOHYDRATES AND AMINO SUGARS IN AQUATIC SAMPLES BY ION-EXCLUSION CHROMATOGRAPHY AND MASS SPECTROMETRY

Karel Hornak, Limnological Station, Institute of Plant Biology, University of Zurich (Switzerland) Coauthors: Pernthaler J

Free neutral carbohydrates and amino sugars were determined in diverse environmental samples of distinct matrix complexity, including lake water, artificial cultivation medium and phytoplankton cultures, using high-performance ion-exclusion chromatography with mass spectrometric (MS) detection. As compared to previous methods, our novel protocol allowed the determination and quantitation of free neutral carbohydrates and amino sugars in aquatic samples at nM concentrations without derivatization or pre-concentration. In addition, for the first time N-acetyl- amino sugars could be directly measured in lake water. Prior to injection, new sample preparation procedure employing glass fiber and hollow fiber filters was applied. Analytes were separated on a strong cation exchange resin under 100% aqueous conditions using 0.1% formic acid as a mobile phase. To achieve low background noise in MS, analytes were detected under a multiple reaction monitoring scan mode with double ion filtering. Detection limits of carbohydrates and amino sugars ranged between 0.2 - 2 nM at a signal-to-noise ratio >5. Error ranged between 1 - 12 % at 0.5 - 500 nM levels. The simple and rapid sample preparation makes our protocol suitable for routine analyses of organic compounds in natural samples.

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PS-9.08. MICRODIVERSITY: ECOPHYSIOLOGICAL DIVERSIFICATION AMONG CLOSELY RELATED POLYNUCLEOBACTER AND LIMNOHABITANS BACTERIA

Matthias Hötzinger, Institute for Limnology (Mondsee), University of Innsbruck, Pfaffing (Austria) Coauthors: Hahn M, Simek K

The bacterial species Polynucleobacter necessarius subspecies asymbioticus (further abbreviated as P. necessarius) and the genus Limnohabitans represent groups of planktonic freshwater bacteria with cosmopolitan and ubiquitous distribution in standing freshwater habitats. P. necessarius comprises on average about 10% and Limnohabitans 9% of total bacterioplankton cells in various freshwater habitats. Both taxa were detected in all climatic zones and over a wide pH range (3.8 - 8.5). The ubiquity of P. n. ssp. asymbioticus was recently explained by intra-taxon ecological diversification, i.e. specialization of lineages to specific environmental conditions. Supplementary, wealth of currently generated genetic data indicates an unforeseen high number of closely related genotypes (microdiversity). Indeed, the presently described species P. necessarius might represent a cryptic species complex. Compared to P. necessarius, less genetic data is available for Limnohabitans; nevertheless, recent research implies that profound intra- taxon diversity does exist within this genus too. However, details on specific adaptations of single genotypes to an environment are not known for both taxa. Hence, the question how closely related genotypes, coexisting in a single habitat, can avoid or at least weaken severe competition remains widely unexplained. To that end, fundamental mechanisms for niche partitioning of coexisting strains are enlightened, i.e. within species P. necessarius and genus Limnohabitans separately, by means of ecophysiological investigations. Growth characteristics for strains of both taxa are tested in situ and in the laboratory. Growth rates at different temperatures under controlled laboratory conditions shed light on thermal adaptations of closely related strains from environments differing in altitude and mean water temperature, respectively. In situ, strains isolated from the same habitat are investigated in dialysis bag experiments, excluding competition and grazing-induced mortality caused by flagellates. Experiments with P. necessarius are carried out in a dystrophic, shallow pond (Pond-1) in the Austrian Alps and Limnohabitans is studied in a meso-eutrophic reservoir (Řimov reservoir) located in South Bohemia, Czech Republic. Differences in the growth potential between the strains of the same taxon and their seasonal changes allow conclusions on the ecological relevance of the observed microdiversity.

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PS-9.09. Microbial Methane Oxidation in the Water Column of the River Elbe

Anna Matousu, Biology Centre of ASCR v.v.i, Institute of Hydrobiology, České Budějovice (Czech Republic) Coauthors: Osudar R, Simek K, Bussmann I

Aerobic microbial oxidation of methane (CH4) is believed to be much less efficient in a riverine water column and estuaries than in methane-productive sites (lakes, peat bogs, etc.). However, almost no quantitative assessment of its role in a river continuum is currently available and we have very limited knowledge on the environmental factors controlling this process. Thus we examined the metabolic activity of aerobic methane-oxidizing bacteria (methanotrophs) and their distribution in the water column along the River Elbe. Additionally, physical and chemical parameters were measured. Analysis of several sampling campaigns has brought gross information about the fate of CH4 in the large river. Concentrations of CH4 dissolved in water were measured by gas chromatography and CH4 oxidation rates were determined with radioactive tracer ([3H]CH4). The range of CH4 concentrations and related methanotrophic metabolic activities varied temporally and spatially along the river profile in the Czech section of the Elbe. Bottom and surface waters had essentially similar values of measured parameters. However, regardless the season we found a consistently repeating pattern in the data characterizing each site. The CH4 oxidation rates correlated with the CH4 concentrations, however, at one site high oxidation rates were repeatedly detected, despite only moderate CH4 concentrations, while additional parameters (water temperature, nutrients, O2 content, etc.) could not explain this observation. In the Elbe estuary, we found similar pattern in the measured data over all sampling sites. However, the site with the highest CH4 concentrations (between Geesthacht and Hamburg port) was moving up- and downstream. The CH4 oxidation rates were tightly correlated with the ambient CH4 concentration, exhibiting a consistent pattern. Further downstream both parameters decreased strongly with the increasing salinity. Of all additionally measured parameters, only the CH4 concentration showed significant correlation with the CH4 oxidation rate on all sites. However, there is an apparent negative correlation between the CH4 concentration and suspended particular matter. Nevertheless, there is an open intriguing question: what site-specific factors may favor methanotrophs at different sites? The data on abundance (assessed by FISH) and population structure (assessed by DGGE) could possibly explain the site specific characteristics observed in the methanotrophic activities.

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PS-9.10. QUANTIFICATION OF THE PROTON PUMP ACTIVITY OF PROTEORHODOPSIN IN VIBRIO CAMPBELLII AND PHOTOBACTERIUM ANGUSTUM

Yu Nakajima, University of Tokyo Atmosphere and Ocean Research Institute, Kashiwa city (Japan) Coauthors: Yoshizawa S, Kogure K

Proteorhodopsin (PR) is a bacterial light-driven proton pump that generates electrochemical proton gradient. PR genes are widely distributed among marine prokaryotes, suggesting that light energy passing through PR may be substantial in marine environment. There are limited studies on the direct measurements of the pump activity using viable cells. Furthermore, to our knowledge, the effects of parameters such as temperature, pH and incubation time on the activity have never been investigated. However, such information is prerequisite to estimate ecological role of PR in marine environments. The purpose of this investigation was to clarify the effects of growth phase, pH and temperature on the PR pump activity using viable cells of Vibrio campbellii BAA-1116. Upon illumination, pH in the chamber started to decrease and returned to the original level when the light turned off. The addition of CCCP suppressed this pH change, indicating that proton pump was functioning under the present experimental condition. The effect of environmental parameters are shown and it implication in marine environments will be discussed.

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PS-9.11. INHIBITORY BIOACTIVE COMPOUNDS PRODUCED BY MARINE STREPTOMYCETES ISOLATED FROM MANGROVE RHIZOSPHERE SOIL OF KHORE KABA’ SHORES

Ismail Saadoun, University of Sharjah (United Arab Emirates) Coauthors: BinHumoudi KM, Kalander MJ, Joubori BA

In this study different marine sediment and soil habitats in the Emirate of Sharjah, UAE were screened for the presence of inhibitory and antiangiogeneticcompounds-producing streptomycetes. Marine sediments and soil samples were enriched to recover streptomycetes on starch casein nitrate (SCN) agar medium. The recovered colonies were macroscopically and microscopically examined, and then their potential to inhibit the growth of different Gram positive and negative multi-resistant bacterial pathogens was tested by the agar diffusion method. Data showed that all recovered isolates were able to produce inhibitory bioactive compound(s) against one or more of the tested pathogens with zones of inhibition ranging between 4 and 55 mm in diameter. However, 3 isolates; KM1, KM2 and KM3; showed maximal inhibition against Pseudomonas aeruginosa with 55, 48 and 45 mm zones of inhibition, respectively. It is noted that the isolate KM18 was able to inhibit all tested pathogens except Klebseilla, with zones of inhibition ranging between 18 and 42 mm. KM1 isolate was further tested for the production of inhibitory metabolites under submerged conditions in SCN broth. The metabolites produced by Streptomyces sp. KM1 was tested for its antiangiogenetic activity and antibacterial inhibition to the growth of E. coli and P. aeruginosa pathogens which showed susceptibility to these metabolites with zones of inhibition of 22 mm for E. coli. The activity of the metabolites was tested by the well-diffusion assay after extraction with butanol:ethylacetate, both pathogens were inhibited with 21 and 22 mm zone diameter, respectively. The concentrated ethyl acetate extract from KM1 strain showed antiangiogensis activity as reflected by the reduction of the neovascular index from 3.1/cm2 to 0.5/cm2. Based on the results of this study it can be concluded that the inhibitory effect of the recovered streptomycetes isolates from unique habitats in Sharjah-UAE may suggest the novelty of the inhibitory/antiangiogenetic compound(s) produced by the Streptomyces sp. KM1 and the other promising strains.

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PS-9.12. HYDROCARBONOCLASTIC BACTERIA FROM A POLLUTED HARBOUR IN SICILY (ITALY): ISOLATION, IDENTIFICATION AND CHARACTERIZATION OF THEIR BIOTECHNOLOGICAL POTENTIAL

Santina Santisi, Istituto per l'Ambiente MArino Costiero (IAMC – CNR), Messina (Italy) Coauthors: Catania V, Catalfamo M, Yakimov MM, Quatrini P, Mancini G, Cappello S

Metabolic specialization is a general biological principle that shapes the assembly of microbial communities. Hydrocarbonoclastic bacteria (HCB) are marine bacteria that are specialised in hydrocarbon degradation and use hydrocarbons almost exclusively as unique C and energy source. HCB become dominant in oil-impacted environments and are particularly adapted for removal of hydrocarbons from contaminated sites through bioremediation treatments. The petrochemical site of Priolo-Augusta-Melilli (Sicily, Italy), is a Site of National Interest (SIN) due to high levels of environmental contamination of the coastline and a specific "national program of environmental remediation and restoration" was developed in order to allow remediation and restoration of contaminated sites. In order to to identify the key hydrocarbon degraders and explore the natural bioremediation potential of the contaminated area, a total of six sediment and sea water cores were collected inside the Priolo Harbour (SR, Italy). After biological (bacterial population diversity, PCR-DGGE) and chemical-physical characterisation (quali-, quantitative measures of hydrocarbons and heavy metals) samples were used, separately, to set enrichment cultures on mineral broth containing different mixtures of linear (C16, C18, C20) and aromatic (phenatrene, pyrene, biphenyl and dibenzothiophene) hydrocarbons and Crude Oil (Arabian Ligth Crude Oil). A total of 159 isolates (82 from seawater and 77 from sediments) were obtained. The sequencing of 16S rDNA showed the most of the isolates belonged to, Alcanivorax (44 %), Marinobacter (17%) and Oleibacter (9%) genera. Data obtained from assays of biodegradation revealed as more interesting bacteria present a very high potential of application in bioremediation techniques; furthermore data obtained give a deeper understanding of the biochemical causes of metabolic specialization and could serve as a foundation for the field of synthetic ecology, where the objective would be to rationally engineer the assembly of a microbial community to perform a desired biotransformation.

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PS-9.13. METABOLIC PATHWAYS OF PSEUDOMONAS FLUORESCENS ICT IN THE PERSPECTIVE OF GROUNDWATER BIOREMEDIATION

Alena Sevcu, Technical University of Liberec (Czech Republic) Coauthors: Sakmaryova I, Baldrian P, Chronakova A

Insufficiency of information on the factors controlling the growth and metabolic capabilities of groundwater bacteria still limits successful implementation of enhanced bioremediation technologies. Molecular analysis can uncover important metabolic pathways, expression of functional genes both in laboratory and in situ. For that purpose we have sequenced the genome of pure culture of P. fluorescens ICT, which was isolated from contaminated site and exhibits flexible catabolism of different pollutants. Genome of P. fluorescens ICT was analysed by 454- pyrosequencing technology. In total, 121 Mb were obtained by two sequencing runs on GS Junior System. The assembly of 454-pyrosequencing data resulted in a construction of 73 contigs with an average length of 99, 068 bps. MG-RAST and Blast2Go were used for gene annotations. The predicted size of the genome was 7.2 MB. Of the total genome sequence, 97.2% were proteins annotated by MG-RAST, 91.2% of annotated features were assigned to functional categories. Tested laboratory strain was found to be closely related to the P. fluorescens Pf-5 (Accession No. CP000076) genome with 96% of genes with E below 10-30. Among others, the bacterium contains 18 genes involved in biphenyl metabolism, 10 involved in the metabolism of chlorinated aromatic compounds and 9 genes for naphthalene and anthracene metabolism. Obtained genome sequence will serve for more detailed analyses of differences between P. fluorescens ICT, P. fluorescens Pf-5 and other Pseudomonas strains to date isolated from the environment. The high throughput analyses should elucidate bacterial biodegradation potential and nutritional demands, and the factors most significantly affecting its applicability in groundwater remediation.

335 THURSDAY 12 SEPTEMBER 2013, 17:30 PS-9. Microbial metabolic specialization: causes and ecological consequences

PS-9.14. GENOMIC DISTRIBUTION OF PHOSPHORUS UTILIZING GENES IN SEVERAL MICROFLORA FROM LAKE STECHLIN

Abhishek Srivastava A, Leibniz-Institute for Freshwater Ecology, Stechlin (Germany) Coauthors: Grossart HP

Phosphorus (P) is an important element to all forms of life. However, in many aquatic systems P is 3- a limiting nutrient in primary productivity. Nevertheless, phosphate (PO4 ) is considered to be a preferred nutrient for microbial growth, alongside various organic carbon sources. Aquatic bacteria consume P which appears to be limiting in algal abundance. A well studied oligotrophic Lake Stechlin is located in the North-Eastern part of Germany and harbors ~1.3x106 bacterial cells/ml. This lake possesses around <2µg/l of soluble reactive phosphorus (Allgaier and Grossart, 2006). Free-living bacteria often co-occur with other organisms which can be a potential source of nutrients. Epilimnic Actinobacteria of the acI cluster usually dominates the bacterioplankton in many temperate freshwater lakes, sometimes reaching up to ~60% of the entire bacterial population. Single cell genomics data obtained from Actinobacteria of ac1 strain indicates at least 20 potential gene candidates involved in the P metabolism, including exopolyphosphatase-coding gene (exoP). Polyphosphatase is experimentally proven to be functional at the protein level and could be an important candidate in avoiding bacterial P-starvation under phosphorus poor aquatic conditions. Two selected examples from the Lake Stechlin are Achromatium and Stentor, whose metagenome analyses suggests that only 1.1% of total gene-pool is involved in P metabolism. P channeling and cycling via life-forms in an aquatic ecosystem is a dynamic process which allows the survival of every species involved in a P-limiting environment. And this could be another important factor in the success of Actinobacteria in freshwater system.

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PS-9.15. CHEMOAUTOTROPHY AND HETEROTROPHY ASSOCIATED TO ELECTROGENIC SULPHIDE OXIDATION IN COASTAL SEDIMENT

Diana Vasquez-Cardenas, Royal Netherlands Institute for Sea Research, Yerseke (Netherlands) Coauthors: Malkin SY, Hidalgo S, Confurius V, Faydaci B, Meysman FJR, Boschker HTS

Recently it was shown that electro-filaments, belonging to the Desulfobulbaceae family, can couple sulphide oxidation at depth to surface oxygen consumption in marine sediments (electrogenic sulphide oxidation). These filamentous bacteria form dense networks that transport electrons vertically over centimetre-long distances to the oxic zone. By spatially separating the redox reaction they have developed a strong competitive advantage over other sulphur oxidizing bacteria in sulfidic marine sediments. However it is unknown how these bacteria grow or how they affect the distribution of other sulphur-dependent bacterial communities. Here we firstly show the induction of electro-filaments via microelectrode profiling and fluorescent in situ hybridization identification in our sediment incubations. Secondly, the active microbial community was characterized by cDNA clone libraries and 13C-incorporation into phospholipid derived fatty acids (PLFA) using propionate and bicarbonate as substrates. cDNA clone libraries of top 3 cm of sediment were dominated by Desulfobulbaceae electro-filaments as well as sequences related to known chemoautotrophic sulphur oxidizers belonging to ε-protoebacteria. Likewise, PLFA patterns of 13C-incorporation showed two distinct microbial signatures most likely corresponding to one heterotrophic community represented by Desulfobulbaceae electro-filaments and another chemoautotrophic community dominated by ε-proteobacteria. Thirdly, sediment was manipulated to link these activities to the metabolism of the electro-filaments. Anoxic incubations and physical cutting of the network have been reported to abruptly halt long-distance sulphide oxidation. Both manipulations of the sediment showed that both heterotrophy and chemoautotrophy were closely coupled to electrogenic sulphide oxidation. In conclusion the newly discovered electron- transport mechanism by electro-filaments provides a new niche for ε-protoebacteria in coastal sediments. Both communities rely on reduced sulphur compounds for energy but the electro- filaments use organic carbon to grow whereas ε-proteobacteria grow on inorganic carbon. As such we propose that the electro-filaments and ε-proteobacteria operate as a novel consortium in the complete oxidation of sulphide in coastal sediments.

337 THURSDAY 12 SEPTEMBER 2013, 17:30 PS-9. Microbial metabolic specialization: causes and ecological consequences

PS-9.16. ACCURACY OF COMMUNITY ANALYSIS BY NEXT GENERATION SEQUENCING: LESSONS FROM A DEFINED MIX OF AQUATIC PROTISTS

Joerg Villiger, Limnological Station, University of Zurich (Switzerland) Coauthors: Wylezich C, Pernthaler J

Next generation sequencing is increasingly used to analyse microbial diversity in complex environmental samples. A lot of data are produced and there is a variety of different workflows. We tested different freely available analysis pipelines, as well as a custom designed solution, for their accuracy for the analysis of an artificially composed assemblage. This mock community consisted of 6 species of aquatic protists mixed at defined abundances. We also compared various bioinformatic approaches within the pipelines, such as pre-filtering techniques to eliminate sequencing and homopolymer errors, or multiple vs. pairwise sequence alignments. The results were rather diverse, especially with respect to the overestimation of the total numbers of operational taxonomic units (OTUs), but also in the numbers of species that were actually recovered. For example, using USearch, the number of OTU’s could differ by the factor of 20 depending on the used filtering techniques. In particular, we observed a great influence of the method for identifying chimeric sequences, as well as of the time point when this search was carried out during the workflow. Error correcting tools such as PyroNoise / AmpliconNoise and Acacia dramatically reduced the number of spurious OTUs to reasonable levels, but also led to the loss of two out of six species. Depending on the data, the choice of the most appropriate pipeline, and especially of proper parameter settings within the respective workflows, appears to be crucially important. In any case a thorough examination of the produced results is essential, and blind trust in the default results of any analysis method does not seem to be an option.

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PS-9.17. BACILLUS SUBTILIS; PARACOCCUS PANTOTROPHUS AND THIOBACILLUS DENITRIFICANS: THE THREE-BLADE SWISS ARMY KNIFE OF AQUATIC BIOREMEDIATION?

Jutta Zwielehner, BIOMIN Holding GmbH, Herzogenburg (Austria) Coauthors: Weber B, Santos GA, Encarnacao P

During the last decades, the rising demand for seafood led to a substantial growth of the aquaculture industry within the food-producing sector. High stocking densities led to dramatic disease outbreaks and severe environmental contamination. In response to these challenges, pond and water quality management became a real industry focus and aquaculture probiotics are developed to antagonize pathogens, enhance the innate immune system and to drive the bioremediation of toxic metabolites in pond water and pond bottom. Nitrification and denitrification as well as sulfite reduction are crucial tasks to be fulfilled by pond bioremediating probiotic strains. We submitted strains of Bacillus subtilis, Paracoccus pantotrophus and the chemolithoautotrophic Thiobacillus denitrificans to extensive in vitro screening. In the present work we discuss their suitability for synergistic probiotic pond bioremediation. Nitrification and denitrification by B. subtilis and P. pantotrophus were assessed in modified Brunner mineral medium (DSMZ number #462). T. denitrificans was grown in modified DSMZ medium #113 with CO2 as carbon source. The amount of nitrate, nitrite, ammonium ions as well as sulfites and sulfates in the cell-free culture supernatants was assessed with MERCK test kits. In vitro experiments showed that B. subtilis and P. pantotrophus removed excess nitrite from the growth medium under aerobic and anaerobic conditions. However, P. pantotrophus was more efficient compared to B. subtilis. B. subtilis reduced nitrate, but only under anaerobic conditions. P. pantotrophus performed denitrification under both anaerobic and aerobic conditions. Hence, we assume that this strain performs co-respiration of nitrate and oxygen. During prolonged cultivation of T. denitrificans, denitrification coupled to sulfite reduction was observed. The results suggest that the investigated bacteria might have synergistic effects on pond bioremediation. In situ experiments in shrimp ponds visibly improved water quality and pond bottom soil conditions as well as animal growth characteristics.

339 THURSDAY 12 SEPTEMBER 2013, 17:30 PS-10. Microbial autoecology and coevolution

PS-10.01. FRESHWATER PROKARYOTE AND VIRUS COMMUNITIES CAN ADAPT TO GRADUALLY INCREASING SALINITY THROUGH CHANGES IN THEIR STRUCTURE AND INTERACTIONS

Yvan Bettarel Y, Institute of Research for Development (IRD), Hanoi (Vietnam) Coauthors: Combe M, Bouvier T, Pringault O, Rochelle-Newall E, Bouvier C, Agis M, Thupham T, Torreton JP, van Chu T

Little information exists on the ecological adaptive responses of riverine microorganisms to the salinity changes that typically occur in transitional waters. This study examined the strict effects of a gradual increase in salinity (+3 o/oo per day for 12 days) on freshwater virus and prokaryote communities collected in the Red (northern Vietnam). The abundance, activity, morphology and diversity of both communities were examined along this simulated salinity gradient (0 to 36 o/oo). Three main successive ecological stages were observed: (i) a continuous decline in prokaryotic and viral abundance from the beginning of the e salinization process up to salinity 12-15 o/oo concomitant with a strong decrease in the proportion of active cells, (ii) a shift in both community compositions (salinity 9-15 o/oo) and (iii) a marked prevalence of lysogenic over lytic cycles up to salinity 21 o/oo followed by a collapse of both types of of viral infection. Finally, after salinity 21 o/oo, and up to seawater salinities (i.e. 36 o/oo) the prokaryotic community showed multiple signs of recovery with their abundance and function even reaching initial levels. These results suggest that most of the physiological and phylogenetic changes that occurred within the salinity range 10-20 o/oo seemed to favor the installation of osmotically adapted prokaryotes accompanied by a specific cortege of viral parasites which might both be able to survive and even proliferate in saltwater ter conditions.

340 THURSDAY 12 SEPTEMBER 2013, 17:30 PS-10. Microbial autoecology and coevolution

PS-10.02. MARINE BIOGENIC CACO3 PARTICLES POSSIBLY FORMED BY BACTERIA

Bratbak G, University of Bergen (Norway) Coauthors: Heldal M, Norland S

Biogenic production and sedimentation of calcium carbonate in the ocean has profound implications for the ocean carbon cycle. Coccolithophores, foraminifera and pteropods have been considered the main calcifying organisms. Our study document the presence of an abundant fraction of marine calcium carbonate particles in seawater that presumably are formed by bacteria The particles occur in a variety of different morphologies, in a size range from <1 to >100µm, and in a typical concentration of 104-105 particles L-1 (size range counted 1-100µm). The morphology suggests that some particles are formed in relation to extracellular polymeric substances and surfaces. Quantitative estimates of annual averages suggests that the pure calcium particles we counted in the 1-100µm size range account for 2-4 times more CaCO3 than the dominating coccolithophoride Emiliania huxleyi and for 21% of the total concentration of particulate calcium. Due to their high density, we hypothesize that the particles sediment rapidly and therefore contribute significantly to the export of carbon and alkalinity from surface waters. The biological and environmental factors affecting the formation of these particles and possible impact of this process on global atmospheric CO2 remains to be investigated.

341 THURSDAY 12 SEPTEMBER 2013, 17:30 PS-10. Microbial autoecology and coevolution

PS-10.03. THE MICROSCALE DISTRIBUTIONS OF BACTERIA AND VIRUSES IN THE MURRAY RIVER

Lisa Dann, Flinders University, Adelaide (Australia) Coauthors: Mitchell J, Smith R, Newton K

The Murray River supplies the majority of Australia’s domestic and agricultural water. Despite this importance the Murray’s microbial community has received minimal attention. Flow cytometric analysis revealed the presence of two viral and two bacterial subpopulations near the mouth of the river. Abundances ranged from 0.9 to 1.6 x 107 cells ml-1 for bacterial and 1.7 to 6.7 x 107 cells ml-1 for viral subpopulations. The virus:bacteria ratio (VBR) was 2.4 to 3.4, indicating an environment where bacterial productivity is high and viral infectivity is high. The air-water and sediment-water interface, as well as areas of differing flow rates were explored and revealed no difference in bacterial or viral abundance between them (p > 0.39). “Hotspots”, areas of elevated abundance, for bacterial and viral subpopulations reached a maximum of 31-fold difference in heterogeneity over the 1.8 cm x 11.3 cm sampling area. These bacterial and viral “hotspots” were correlated indicating a tight coupling between the viral and bacterial subpopulations. The steep gradients seen from the presence of these microscale hotspots would be missed if the mean field approach was employed and hence shows the importance of high resolution sampling.

342 THURSDAY 12 SEPTEMBER 2013, 17:30 PS-10. Microbial autoecology and coevolution

PS-10.04. VIRAL DECAY IN BENTHIC DEEP-SEA ECOSYSTEMS

Antonio Dell’Anno A, Department of Life and Environmental Science - DISVA, Polytechnic University of Marche, Ancona (Italy) Coauthors: Corinaldesi C, Danovaro R

Marine viruses represent a significant source of mortality for a wide range of organisms, and they influence the ecological processes and biogeochemical cycles of the oceans of the World. Integrating the viral component into global models of carbon cycling and nutrient regeneration is becoming a priority for an improved understanding of the functioning of marine ecosystems. Viral dynamics are the result of the balance between the rates of viral production and decay. However, while an increasing amount of information on viral production is becoming available from both pelagic and benthic systems, limited information is still available on the rates of viral decay. To provide new insights on viral dynamics, we carried out contextual measurements of viral production and decay rates in a wide variety of benthic deep-sea ecosystems, spanning a broad range of environmental and trophic conditions. The net viral production and decay rates were significantly correlated, but viral decay did not balance viral production at any of the benthic deep- sea sites investigated. We estimated that the carbon released by viral decay significantly contributed to the total C released by virus-induced prokaryotic mortality. Viruses non-infecting prokaryotes can also remain as a potential food source for benthic consumers, suggesting that viral decay can play an important role in benthic trophodynamic and biogeochemical cycles of the largest ecosystem of Earth.

343 THURSDAY 12 SEPTEMBER 2013, 17:30 PS-10. Microbial autoecology and coevolution

PS-10.05. TRACKING VIRUSES IN THE `MILKY WAY´: VIRUS OCCURRENCE ALONG A TURBIDITY GRADIENT IN GLACIER-FED LAKES

Fabian Drewes, Institute of Ecology, Lake and Glacier Ecology Research Group University of Innsbruck (Austria) Coauthors: Sommaruga R

Viruses in oligotrophic alpine glacier-fed lakes encounter not only low host abundances, but also high inorganic turbidity due to the input of `glacial flour´. These minerogenic particles in the size range of clay to silt may lead to unspecific viral adsorption and thus be a major source of removal of viruses in this type of lake. In this study, we focus on the distribution of viruses along a turbidity gradient in four lakes. Whereas three lakes were glacier-fed and interconnected, the fourth one was clear because its connectivity to the receding glacier was lost. Samples were taken four times during the ice-free season from beginning of July till October and along the water column. Virus like particles (VLP) were stained with SYBR Gold and enumerated by epifluorescence microscopy. An experiment to test the effect of the addition of glacial particles on the recovery of T4 bacteriophages was done. Further, an experiment with mytomicin C was conducted to evaluate the presence of lysogenic viruses. The experiment with T4 bacteriophages indicated that there was not significant difference with the control (i.e., absence of glacial particles). Among the turbid lakes, VLP abundance increased with distance to the glacier ranging between 4.4 x 105 VLP mL-1 in the most turbid lake in July and 9.5 x 106 VLP mL-1 in the least turbid lake in October, whereas bacterial abundance peaked in August. In the clear lake, the maximum abundance (1.2 x 107 VLP mL-1) was observed by the end of August, coinciding with a peak in bacterial abundance. Mytomicin C addition to samples from a turbid and the clear lake resulted only in a minor (12%) increase in viral abundance. This study gives first insights into the viral distribution and life cycles in turbid glacier-fed lakes in comparison to a clear lake. Further, our results indicate that though viral abundance was lower in turbid lakes than in the clear one, viral loss by unspecific adsorption to particles with very low organic coating may be less important than expected.

344 THURSDAY 12 SEPTEMBER 2013, 17:30 PS-10. Microbial autoecology and coevolution

PS-10.06. HOST METABOLIC PATHWAY SHIFT TOWARD PURINE AND PYRIMIDINE BIOSYNTHESIS DETECTED IN MARINE VIRAL METAGENOMES

Hagay Enav, Technion-Israel Institute of Technology, Haifa (Israel) Coauthors: Mandel-Gutfreund Y, Béjà O

Viral genomes often contain metabolic genes that were acquired from microbial genomes (auxiliary genes). It is assumed that these genes were fixated in the viral genomes as a result of a selective force, favoring viruses that acquire specific metabolic functions. The higher fitness of viruses that carry auxiliary genes results in enrichment of these genes in the viral population. While some auxiliary genes are known to be found in viral genomes, there is a great importance in assessment of the genes that are enriched in viral metagenomes, in order to decipher which metabolic functions promote viral fitness in the environment. In this work we wish to indentify enriched viral auxiliary genes and to map these genes to metabolic pathways, to better understand which metabolic functions are important for viral reproduction. We have used ~20, 000 metagenomic reads from the GOS (Global Ocean Survey) dataset that were previously characterized as viral (Sharon, Battchikova et al. 2011) to search for enriched auxiliary genes, compared to the entire GOS dataset. All reads were annotated using the KEGG Ortholog (KO) database and enriched KO’s were mapped to KEGG pathways. We have found 58 enriched KEGG pathways in the studied viral metagenomes. We show that the pathways with the highest enrichment score are Purine and Pyrimidine metabolism and that many other viral enriched metabolic pathways are closely associated with purine and pyrimidine metabolism pathways, in the global metabolism network we created. We hypothesis that many of the auxiliary metabolic functions found in viruses serve the overall function of nucleotide synthesis and by that increase viral reproduction. Sharon, I., N. Battchikova, et al. (2011). "Comparative metagenomics of microbial traits within oceanic viral communities." ISME J 5(7): 1178-1190.

345 THURSDAY 12 SEPTEMBER 2013, 17:30 PS-10. Microbial autoecology and coevolution

PS-10.07. HABITAT PREFERENCE OF PHAEOBACTER-RELATED MEMBERS OF THE ROSEOBACTER CLADE ACCESSED BY HIGH-THROUGHPUT ISOLATION

Heike M. Freese, Leibniz-Institute DSMZ, Braunschweig (Germany) Coauthors: Overmann J

In marine ecosystems, members of the Roseobacter clade are highly abundant. They account for up to 50% of all bacterial phylotypes present and are characterized by a large phylogenetic and phenotypic diversity. Bacteria of the genus Phaeobacter have several particular physiological features including the production of AHLs, algicides and the antibiotic tropodithiethic acid. In addition, they can switch from free-living to surface-associated mode of growth and contain numerous plasmids. This genus therefore represents a suitable model to elucidate the evolutionary mechanisms underlying the divergence within the Roseobacter clade by population genetics approaches. The latter require a broad range of strains from diverse marine habitats, but only few members of the genus are sufficiently characterized so far. Therefore, we performed liquid and biofilm-specific high-throughput isolation strategies in defined oligotrophic media with samples from 20 different marine habitats. Cultivated bacteria were screened via a specific PCR targeting the genus Phaeobacter and close relatives and sequenced. Our strategies enriched about 500 (7% of all grown enrichments) Phaeobacter–related bacteria which formed 30 sequence- based operational taxonomic units (OTUs, 1% similarity). A large fraction of positive cultures (16%) was enriched from zooplankton. For instance, many Pelagicola litoralis strains were enriched from zooplankton of the North Sea and Leisingera nanhaiensis strains were obtained from mussels. Phaeobacter sp. were exclusively enriched from zooplankton and crustacean from different geographic locations. In particular, numerous and microdiverse representatives of the species Phaeobacter arcticus were cultivated. Variations in the OTU composition among the different habitats suggest a habitat preference of the different lineages of the Roseobacter clade. With the aim of identifying ecotypes of Phaeobacter sp., a total of 28 Phaeobacter sp. genomes have been sequenced and are currently assembled. Comparisons of the genome sequences will be used to identify genes under natural selection and to follow genome evolution and bacterial speciation in the model genus Phaeobacter.

346 THURSDAY 12 SEPTEMBER 2013, 17:30 PS-10. Microbial autoecology and coevolution

PS-10.08. PREDATION-PREY EVIDENCE ON BIOSTIMULATED DIESEL-DEGRADING BACTERIAL COMMUNITIES

Jean François Ghiglione, CNRS-Laboratoire d'Océanographie Microbienne LOMIC (France) Coauthors: Sauret C, Böttjer D, Tallarmin A, Guigue C, Conan P, Pujo-Pay M, Goutx M

Both viral lysis and protistan grazing of bacteria (top-down control) has often been assumed to play a pivotal role in bacterioplankton abundance, diversity and activities. Nevertheless, their concomitant impact on bacterial assemblages remains largely unknown. We designed seawater mesocosm experiments to investigate the effect of heterotrophic nanoflagellates (HNF) and viruses on bacterial abundance, diversity and activities (production, ecto-enzymes, alkane and PAH degradation) in unpolluted vs. diesel polluted conditions under unlimited nutrient condition (biostimulation). In the polluted mesocosms, we observed a classical prey-predator cycle, with a higher control of bacterial abundance by viral lysis (infected cells counted by transmission electron microscopy) compared to HNF grazing (grazing experiment by dilution technique). Massive pyrosequencing of the 16S rDNA showed that the opportunistic Vibrio sp. decreased drastically according to the “killing the winner” principle, while Percisivirga, Oleispira and Methylophaga dominated the community after the predation peak with higher cell-specific activities that ensured a steady oil biodegradation during the course of our experiment (2 weeks). Previous studies have observed changes in bacterial abundance, diversity and activities in response to environmental constrain, but these results are the first evidence of the role of HNF and viral predation pressure in this complex process.

347 THURSDAY 12 SEPTEMBER 2013, 17:30 PS-10. Microbial autoecology and coevolution

PS-10.09. DYNAMICS OF AUTO- AND HETEROTROPHIC PICOPLANKTON AND ASSOCIATED VIRUSES IN LAKE GENEVA

Stéphan Jacquet, INRA CARRTEL, Thonon Les Bains (France) Coauthors: Parvathi A, Zhong X, Sriram PRA

Microbial dynamics has been rarely investigated in Lake Geneva, which is paradoxically the largest lake in Western Europe. From a 5-month survey, we report dynamic patterns of free living viruses, bacteria and small phytoplankton abundances in response to a variety of environmental parameters. For the first time, we fractionated primary production to separate the contribution of different size-related biological compartments and measured both bacterial and viral production in addition to experiments conducted to appreciate viral-induced bacterial mortality. All in all, we observed that there were marked seasonal and vertical variations in abundances and production. The impact of viral lysis on both bacteria and picocyanobacteria was found to be higher than grazing activity. Environmental factors varied significantly with depth and month and influenced strongly biological interactions. This poster gives a first insight on viral and microbial ecology of Lake Geneva at selected periods of the year.

348 THURSDAY 12 SEPTEMBER 2013, 17:30 PS-10. Microbial autoecology and coevolution

PS-10.10. PEAT-INHABITING ACIDOBACTERIA WITH ANAEROBIC LIFESTYLE: ECOLOGY AND PHYSIOLOGY

Irina Kulichevskaya I, Winogradsky Institute of Microbiology, Russian Academy of Sciences, Mosow (Russia) Coauthors: Serkebaeva Y, Dedysh S

Members of the phylum Acidobacteria represent one of the dominant bacterial groups in northern wetlands. As revealed by molecular surveys, these bacteria inhabit both oxic and anoxic peat layers and belong mostly to subdivisions 1 and 3 of the Acidobacteria. With the only exception of Telmatobacter bradus, however, all currently characterized members of these subdivisions are aerobes. Our study, therefore, was focused on those Acidobacteria, which can thrive in anoxic zone of wetlands. The samples were collected from the oxic and anoxic peat layers of the littoral wetland of a boreal lake located in Valaam Island (61o22’N, 31o07’E). The clone libraries were constructed from these samples by amplifying 16S rRNA genes with the Acidobacteria-specific primer set. The phylotypes detected in oxic and anoxic peat affiliated with subdivisions 1 and 3 Acidobacteria. One of the phylotypes specific for anoxic peat was isolated in a pure culture and designated as strain P105. This strain is represented by facultatively anaerobic bacteria capable of fermentation and dissimilatory Fe(III) reduction in anoxic conditions. Comparative 16S rRNA gene analysis revealed that strain P105 belongs to subdivision 3 Acidobacteria and displays 90% 16S rRNA gene sequence similarity to Bryobacter aggregatus, the only member of this subdivision with validly published name. Based on the characteristics determined in our study, we propose to classify the novel acidobacterium as representing a novel genus and species, ‘Paludibaculum fermentans’ gen. nov., sp. nov. The finding of Fe(III)-reducing capability in strain P105 extends our understanding of physiology and ecological roles of peat-inhabiting acidobacteria.

349 THURSDAY 12 SEPTEMBER 2013, 17:30 PS-10. Microbial autoecology and coevolution

PS-10.11. CELLULAR CAPABILITIES OF “SULFURIMONAS GOTLANDICA” STR. GD1 IN REDOX GRADIENTS

Matthias Labrenz, Leibniz Institute for Baltic Sea Research Warnemuende (IOW), Rostock (Germany) Coauthors: Rogge A, Götz F, Vogts A, Jost G, Jürgens K, Cypionka H

Oxic-anoxic interfaces of the pelagic central Baltic Sea are characterized by manifold redox- sensitive nutrient fluxes, which are relevant for biogeochemical cycles of the whole Baltic proper. Previous investigations revealed that their microbial communities are dominated by only a few, mainly chemoautotrophic, key microorganisms which catalyze important transformations within the nitrogen (N) and sulfur (S) cycle. In sulfidic waters below the oxic-anoxic interface epsilonproteobacteria of the Sulfurimonas subgroup GD17 are the major contributors to chemoautotrophic production. These bacteria are responsible for the oxidation of reduced sulfur compounds with nitrate by chemoautotrophic denitrification as the major nitrogen loss process in the pelagic central Baltic Sea. Only recently, the first representative of these habitats, “S. gotlandica” str. GD1, was successfully isolated from a Baltic Sea oxic-anoxic interface, serving as a model organism to answer the role of the GD17 cluster in N and S cycles of the central Baltic Sea. Aim of this study was to get more insight into cellular features of GD1, enabling it to move and survive within fluctuating pelagic redox systems. For this, motility behaviour as well as enrichment of GD1 cells in different S2O3 and NO3 gradients was determined. In addition, potential cellular N 15 34 and S enrichment or even storage were investigated by N-NO3 and S-S2SO3 incubation experiments and coupled to NanoSIMS analyses. After anoxic incubation in tube gradient systems, enrichment of GD1 cells were optically visible as white bands. Their extension increased with increasing substrate concentrations, potentially caused by overlapping gradients in the medium. Average speed of GD1 cells was 25µm s-1 with maximal speed well over 100µm s-1. 34S was intensely but 15N only slightly enriched in GD1 cells. Thus, especially sulfur, but of unknown oxidation state yet, could potentially be stored in the cell and oxidized in nitrate-containing water masses. We assume that these cellular capabilities of GD1 are indicative for their adaptation to micro turbulences in Baltic redoxzones, allowing fast localization of small substrate concentrations at small distances.

350 THURSDAY 12 SEPTEMBER 2013, 17:30 PS-10. Microbial autoecology and coevolution

PS-10.12. LONG-TERM PICOCYANOBACTERIA DEVELOPMENT IN AN ATHALASSOHALINE WARM- MONOMICTIC LAKE ALCHICHICA: VIRUS- VS. CILIATE-CONTROL?

Miroslav Macek, National Autonomous University of Mexico, FES Iztacala, Dept. Tropical Limnology, Tlalnepantla (México) Coauthors: Montiel-Hernández JR, Flórez-Márquez AE, Callieri C

Autotrophic picoplankton (APP) has been monitored regularly in Lake Alchichica (Puebla/Veracruz; Mexico) for nearly 10 years. In the present study, the control of APP development by viruses is analysed. The maximum cyanobacteria abundance was localised within the water column using WET-Labs ECO Triplet fluorometre and oxygen production by 2 µm fraction was measureed at four depths using clear & dark bottles. Autofluorescence and DAPI staining combined with an image analysis (Image J) were applied to evaluate APP and bacterial biomass, respectively. The Sherrs´ fluorescently labelled bacteria-protocol was employed to evaluate a role of ciliates. Viruses were estimated microscopically as “virus like particles” (VLP) according to SYBR Gold protocol, taking CCD camera images. APP were peaking (over 106 cells/mL) during transition between mixing- and stratification period, being responsible for important oxygen production only within the epilimnion; Synechococcus strains were molecularly identified in the isolates. Viruses (107 to 108 VLP/mL) peaked in the surface layer during mixing or in the metalimnion. Analysing both VLP stratification and the annual development pattern, VLPs were coupled apparently more tightly with APP than with bacteria numbers; a large proportion of picyonabacteria phages within VLP is hypothesised. Additionally, both elevated ciliates’ APP elimination during mixing period, and the maximum APP elimination around the oxycline in the late stratification, roughly coincided with VLP maxima. Generally, viruses might be responsible for APP dynamics in the lake, enhancing the ciliate predation pressure-effect.

351 THURSDAY 12 SEPTEMBER 2013, 17:30 PS-10. Microbial autoecology and coevolution

PS-10.13. FRACTURE ZONES IN THE MID ATLANTIC RIDGE MODIFY PROKARYOTIC AND VIRAL COMMUNITIES IN DEEP-WATER MASSES

Simone Muck, Faculty Center of Ecology, Department of Marine Biology, University of Vienna (Austria) Coauthors: Griessler T, Köstner N, Klimiuk A, Winter C, Herndl GJ

We hypothesized that mixing zones of deep-water masses in the ocean can be seen as ecotones and consequently can be considered as hotspots of prokaryotic and viral activity and diversity due to changes in the physico-chemical characteristics of the water layers. To test this hypothesis, we examined the mixing of deep-water masses where it is most intense, i.e., in regions where water masses are funneled through narrow canyons in the Mid Atlantic Ridge such as the Vema Fracture Zone (VFZ, ≈10°N). There, North Atlantic Deep Water (NADW) and Antarctic Bottom Water (AABW) are subjected to intense vertical mixing and hence to elevated nutrient input by resuspension of sediments. We determined successional changes in the viral and prokaryotic community in the deep-water masses during their flow through the fracture zone, reflecting a higher lytic viral production was detected in the lower NADW of the VFZ than outside the VFZ linked to elevated viral abundance and virus-to-prokaryote-ratios in this water layer. Lysogenic viral production was variable throughout the water column, both inside and outside the VFZ. Furthermore, prokaryotic leucine uptake, as a proxy for heterotrophic activity, decreased less with depth inside the VFZ than outside. Our study indicates that deep-water masses are highly modified during their flow through narrow deep-water canyons and that the increased turbulence observed there has a strong impact not only on the abundance and activity of viruses and their prokaryotic hosts but also on the community composition.

352 THURSDAY 12 SEPTEMBER 2013, 17:30 PS-10. Microbial autoecology and coevolution

PS-10.14. FLOW-SORTING OF UNCULTIVABLE ULTRAMICROBACTERIA ACCORDING TO THEIR TAXONOMIC AFFILIATION

Stefan Neuenschwander, Limnological Station, Institute of Plant Biology, University of Zurich (Switzerland) Coauthors: Pernthaler J, Posch T, Salcher MM

Ultramicrobacteria numerically dominate the bacterioplankton in many natural aquatic systems. Understanding their genetic properties is therefore of high interest, however, cultivation of those microbes is still very challenging. Separating phylogenetically defined populations from their natural communities prior to (meta-) genome analysis could therefore be a promising alternative. On way to achieve such a physical separation is to combine fluorescence in situ hybridisation (FISH) and flow cytometry. Such protocols are available since the nineties and have been successfully applied to samples originating from nutrient rich environments. Limited signal intensities however hindered a broad application to samples from natural aquatic environments. The introduction of CARD-FISH (Catalyzed reporter deposition-FISH) based protocols partly solved this problem, but when applied to ultramicrobacteria, insufficient signal to noise ratios are still an issue. We aimed to improve the sensitivity of such a protocol by complementing it with antibody mediated secondary tyramide signal amplification. For evaluation we used samples from the oligo- mesotrophic Lake Zurich and a oligonucleotide probe specific for the highly abundant but so far uncultivable LD12 (SAR11 IV) cluster of Alphaproteobacteria. Compared to previously existing protocols we observed superior signal to noise ratios which allows high purity sorting. It is however not practicable to sort sufficient numbers of cells for direct sequencing. We are therefore working on a protocol combining CARD-FISH, flow-sorting, and multiple displacement amplification (MDA) to obtain sufficient yields of genomic DNA for subsequent genomic analysis.

353 THURSDAY 12 SEPTEMBER 2013, 17:30 PS-10. Microbial autoecology and coevolution

PS-10.15. A PRELIMINARY EXAMINATION OF CORAL-ASSOCIATED VIRAL COMMUNITIES IN THE VAN PHONG BAY (VIET NAM)

Hanh Kim Nguyen, Institute of Oceanography of Nha Trang (Vietnam) Coauthors: Bettarel Y, Bouvier T, Baudoux AC, Bouvier C, Bouvy M, Debroas D, Desnues C, Doan NH, Ferrier-Pages C, Monteil S, Nguyen TT, Nguyen NL, Reynaud S, Rochelle-Newall E, Sime- Ngando T, Tran QH

Coral-associated viruses are attracting increasing interest from environmental microbiologists seeking to understand their function and involvement in coral health. However, surprisingly little is known about their ecological traits (abundance, activity and diversity) and the specific interactions with their bacterial host within the coral holobiont. In this study, a quantitative and qualitative characterization of both communities (i.e. viruses and bacteria) was conducted on the mucus of 9 different coral species collected in two contrasting sites: a marine protected area and a fish- farming area, both located in the Van Phong Bay (Viet Nam). In the mucus samples, viral (m = 3.7 x 107 vir. ml-1) and bacterial (m = 4.8 x 106 cells ml-1) abundances were, on average, respectively 13 and 2-fold higher than in the surrounding water. Both communities were seemingly influenced by the water quality as corals in the vicinity of fish farms were harboring almost twice the amount of viruses, and 15% more bacteria than those sampled in the protected area. The bacterial physiological state inferred from the CTC (5-cyano-2, 3-ditolyl tetrazolium chloride) method revealed that active respiring cells was also 3-fold more abundant in the mucus (m = 27% of the total count) than in the water (m = 9%) but no difference could be detected between the mucus of the two sites. Finally, the examination of bacterial and viral diversity under different methodological angles (metagenomics, transmission electron microscopy, DGGE and Biolog Ecoplates), also showed remarkable differences between coral and water samples, and diversity was also strongly impacted by aquaculture activities. Overall, our findings demonstrate that corals harbor specific assemblages of highly abundant, active and diversified viral and bacterial communities, which have probably experienced a divergent co-evolution trajectory compared to their surrounding planktonic counterparts. Coral mucus, given its unique physio-chemical characteristics and sticking properties, therefore can be regarded as a highly selective niche that enriched a specialized symbiotic microbial and viral life.

354 THURSDAY 12 SEPTEMBER 2013, 17:30 PS-10. Microbial autoecology and coevolution

PS-10.16. VIRAL INFECTION STRATEGIES OF BACTERIOPLANKTON IN A DEEP FRESHWATER LAKE

Stéphanie Palesse, L.M.G.E Université Blaise Pascal , CNRS, Aubiere (France) Coauthors: Colombet J, Sriram PRS, Sime-Ngando T

Nowadays, it is admitted that the ecological importance of viruses (nutrients recycling, microbial mortality, genes transfers) is closely related to the type of replication cycle established by the viral communities (Lytic or lysogenic). The potential biological or physico-chemical conditions that influence the importance of these two life cycles, as previously documented in Phage-Hosts systems, remains somewhat unclear in natural aquatic ecosystems. So therefore, this study aims to determine the factors that influence the dynamic of viral replication in freshwater ecosystems. We investigated temporal and vertical variabilities in microbial abundances (bacteria, viruses and autotrophic picoplancton) and viral life strategies from April to December 2011 in the deep (Zmax= 92m) meromictic volcanic Lake Pavin (Massif Central, France) which is characterized by strong physico-chemical gradients. The main results suggest that the dynamic of viral replication cycles were largely controlled by the physiological states and the metabolic activity of the main prokaryotic hosts which in turn was related to the concentrations of nutrients. Viral lytic infection was highest in the metalimnion and on average viruses destroyed 35% of daily bacterial production, whereas the maximum percentage of lysogenic bacteria (11%) was observed in epilimnion region of water column. Future works will allow us to determine the intracellular mechanisms of host cells to “decide” the viral life strategies in natural aquatic ecosystems.

355 THURSDAY 12 SEPTEMBER 2013, 17:30 PS-10. Microbial autoecology and coevolution

PS-10.17. METAGENOMICS OF PHAGE-HARBORED METABOLIC GENES IN THE RED-SEA

Alon Philosof, Technion-Israel Institute of Technology, Haifa (Israel) Coauthors: Béjà O

Marine viruses comprise the largest reservoir of genetic diversity in the ocean and are major players in oceanic processes. Recently, marine carrying photosynthetic genes were discovered, possibly increasing phage fitness. . Phages may contribute to geobiochemical processes not only indirectly by predation of bacteria and affecting bacterial populations, but may also have a direct effect by constantly tinkering genes related to these processes. In order to gain knowledge on the abundance of phage-harbored metabolic genes and the extant to which they are expressed in the marine environment, genomic (gDNA), viral (vDNA) and transcriptomic (cDNA) samples were collected from the Gulf of Aqaba and sequenced using 454 pyrosequencing. Our results show that several metabolic processes are enriched in the viral fraction of both the vDNA and gDNA samples. Photosynthesis is more enriched in the vDNA fraction and Aminoacyl- tRNA biosynthesis is highly enriched in both cases. Cyanophages are highly abundant in both the gDNA and vDNA fraction and contribute the majority of the photosystem II protein D1 genes, suggesting active infection during sampling. Furthermore, pico-Eukarya were highly abundant at the cDNA fraction, suggesting an important contribution to active photosynthesis in the marine environment. In addition, Bacterial SAR11, SAR86 and archaeal proteorhodopsins as well as recently described viral-like rhodopsins were detected on the gDNA level. On the cDNA level, only SAR11 and SAR86 proteorhodopsin transcripts were detected. Finally, we show that phage- harbored genes involved in metabolism as well as signal transduction and signaling are highly abundant in the Red Sea virome suggesting a significant role of phages in this marine environment.

356 THURSDAY 12 SEPTEMBER 2013, 17:30 PS-10. Microbial autoecology and coevolution

PS-10.18. ULTRA-ABYSSAL SEDIMENTS OF THE IZU-OGASAWARA TRENCH ARE A HOT SPOT OF VIRAL ACTIVITY AND PROKARYOTIC BIODIVERSITY

Eugenio Rastelli, Università Politecnica Delle Marche (Italy) Coauthors: Danovaro R, Corinaldesi C, Dell'Anno A, Nunoura T

Viruses are the most abundant biological entities in the world’s oceans (approximately 4x1030 viruses) and play a key role in the dynamics of most biological components and in the functioning of marine ecosystems, by contributing to global biogeochemical processes. The role of viruses becomes apparently more important in the deep ocean, where beneath 1000m depth, viral infections and subsequent cell lysis (the so called viral shunt) convert nearly all of the prokaryotic C production into cellular debris and labile macromolecules (in particular DNA and RNA), which can be used by other prokaryotes and microbial heterotrophs for sustaining their metabolism. When released by the lysed cells the extracellular DNA can become also potentially important for the gene flux, but the extent of these processes on the deep ocean and the factors controlling these mechanisms are almost completely unknown. In order to test whether these processes were affected by pressure and other environmental variables, an investigation was carried out on virus- prokaryote interactions in the Ogasawara trench and the adjacent abyssal plain. Here we report the preliminary results of analyses conducted on samples collected along the water column, in surface and sub-surface sediments inside the Ogasawara trench (down to 9776 m depth) and on the abyssal plain outside the trench (at 5747 m depth). We investigated viral abundance and virus- induced prokaryotic mortality. Bacterial and archaeal SSU RNA and amoA genes were quantified by real-time quantitative PCR. Prokaryotic diversity was also assessed by bacterial and archaeal rRNA gene clone libraries, and further pyrosequencing of previously separated intracellular, extracellular and viral DNA pools gave new insights on the functional diversity of the different systems. We found higher abundances of viruses, bacteria and Archaea and higher rates of viral production and cell lysis at hadal depths, coupled with higher amounts of extracellular DNA. We found significant differences in the sediment and pore water geochemistry comparing abyssal and hadal sediments. Viral, bacterial and archaeal abundance and the rates of viral production and cell lysis, were found higher inside the trench. Prokaryotic diversity was higher inside the trench and taxa within the trench were different from those inhabiting the abyssal sediments (high β- diversity). Our results indicate that the Izu-Ogasawara trench is a bioreactor of microbial activity, with viral infections enhancing prokaryotic metabolism and the biogeochemical recycle of organic matter, with positive feedbacks on prokaryotic turnover biodiversity.

357 THURSDAY 12 SEPTEMBER 2013, 17:30 PS-10. Microbial autoecology and coevolution

PS-10.19. APPLICATION OF A RAPID METHOD FOR BACTERIA DETECTION, IN ORDER TO EVALUATE THE EFFECT OF DIFFERENT ENVIRONMENTAL VARIABLES IN THE EFFICIENCY OF PHAGE THERAPY IN FISH FARMS

Yolanda J Silva, University of Aveiro (Portugal) Coauthors: Costa L, Pereira C, Calado R, Gomes N, Cunha A, Almeida A

The growing importance of aquaculture worldwide, offset the increasing pressure on natural fish populations, and the fact that several fish farms often suffer great economic losses due to infections caused by pathogens, including multidrug-resistant bacteria requires the search for alternative methods such as phage therapy, for the inactivation of pathogenic bacteria. Phage therapy consists on the use of bacteriophages (viruses that infect bacteria) to inactivate pathogenic bacteria and presents several advantages compared to conventional methods. Their use requires, however, the new understanding of kinetic phenomena unknown in conventional treatments. The kinetic theory indicates that the concentration of bacteria and phages applied, as well as stability of this relationship with the environmental factors can be critical. In order to gain knowledge about these relationships it is necessary to develop microbiological analysis methods faster than conventional ones. The aim of this work was to apply a rapid bacterial detection method to evaluate the effect of physical and chemical properties of aquaculture waters (e.g., pH, temperature, salinity and organic matter) on the efficiency of phage therapy under controlled experimental conditions, in order to provide a basis for the selection of the most suitable protocol for subsequent experiments. A bioluminescent genetically transformed E. coli was selected as a model microorganism to monitor real-time phage therapy kinetics through measurement. Phage survival was not significantly affected by the natural variability of pH, temperature, salinity and organic matter concentration of the aquaculture waters in temperate climate. Nonetheless, the efficiency of phage therapy was affected by the variation of salinity and organic matter content of the waters. As the effectiveness of phage therapy increases with water salt content, this approach appears to be a suitable choice for marine aquaculture systems. With this method it was possible to select the optimal concentration of phages to be added to bacterial cultures for an effective inactivation and was also possible to monitor the phage infection process in real time, using a faster, cheaper and much less laborious approach than the conventional methods. The success of phage therapy may also enhance in non-marine systems through the addition of salt, whenever this option is feasible and does not affect the survival of the treated species.

358 THURSDAY 12 SEPTEMBER 2013, 17:30 PS-10. Microbial autoecology and coevolution

PS-10.20. INFLUENCE OF ORGANIC MATTER CONTENT IN THE INACTIVATION OF THE FISH PATHOGENIC AEROMONAS SALMONICIDA BY A NEW ISOLATED BACTERIOPHAGE

Yolanda J Silva, University of Aveiro (Portugal) Coauthors: Pereira C, Costa L, Cunha A, Gomes N, Almeida A

The increasing problem of antibiotic resistance in common pathogenic bacteria and the concern about the spreading of antibiotics in the environment, enhance the need to find new methods to control fish pathogens. Phage therapy appears to represent a useful and flexible tool for the inactivation of bacterial pathogens in aquaculture, but the effect of the organic matter content of culture waters on the efficiency of this technology is little studied. The present study aimed to evaluate the effect of organic matter on the efficiency of phage therapy under controlled experimental conditions, in order to provide a basis for the selection of the most suitable protocol for subsequent experiments. A. salmonicida, causative agent of furunculosis, was used to evaluate the effect of organic matter on the phage therapy kinetics. To evaluate the effect of the organic matter concentration, assays were performed in TSB culture medium (1x TSB), TSB 2 times diluted (1:1), TSB 10x diluted (9:1) and PBS. The experiments were performed at a pH of 7.4 and a temperature of 20 °C. The increase in the organic matter concentration increased the rate of bacterial inactivation. When the assays were done in normal TSB medium the highest inactivation was of 3.4 log and was achieved after 8 h of phage therapy. However, when the concentration of TSB was decreased to its half, the maximum rate of inactivation decreased to 2.4 log, but occurred early in time (after 6 h of phage therapy). Using TSB diluted 10 x, the rate of inactivation reached a maximum of 2.0 log after 6 h of phage therapy. When the phage therapy assays were conducted solely in the presence of PBS (maximum reduction of the organic matter content), there was a bacterial reduction of 1.3 log after 12 h of phage therapy. The maximum difference between bacterial inactivation under rich nutrient conditions and poor nutrient condition was of 2.1 log, which correspond to a difference of 62 % in the efficiency of phage therapy. No decrease of phage survival was observed during the 48 h of experiment for phage controls tested without its host, however, when the phage was incubated in the presence of its host, their concentration increased by 1.0 log. Although phage survival was not affected by the organic matter concentration, the efficiency of phage therapy was significantly affected by the variation of the organic matter content of the waters.

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PS-10.21. TEMPORAL AND SPATIAL ABUNDANCE OF BACTERIOPLANKTON AND VIRUSES IN A NORWEGIAN FJORD

Julia Endresen Storesund, University of Bergen (Norway) Coauthors: Sandaa RA, Erga SR, Prestegard S, Thingstad TF

The Sognefjord, located on the west coast of Norway, is one of the largest and deepest fjords in the world. The fjord is separated from the coastal waters by a sill, preventing free circulation of the water below sill depth, but there is a free exchange above with the coastal Norwegian current. Inside the fjord there is a stratification of the water masses with a brackish top-layer, an intermediate layer consisting of coastal water, and the basin water below the sill depth consisting of denser Atlantic water. The basin water is replaced approximately every 8th year, last during the winter of 2010/2011, theoretically removing the old water masses with an established microbial community and replacing it with a new one. Our aims were to: 1) Investigate the community composition of bacterioplankton and viruses, and compare with environmental variables. 2) Measure spatial and temporal changes in microbial community composition. Water was collected from twelve to eight depths and bacterioplankton- and virus-like particles were counted using flow cytometry. Measurements were also done of the chemical properties of the water, bacterial production and total organic carbon (TOC). Physical properties were measured using a conductivity, temperature, and depth (CTD) sensor. In general, the preliminary data indicates a highly dynamic environment in the Sognefjord. An overall decrease in the virus:prokaryot ratio (VPR) with depth was observed. The VPR appear to be influenced by seasonality in the surface layers down to approximately 250m depth, whereas the deeper layers with some exceptions display a more stable virus-prokaryot dynamic. An increase in nitrate, phosphate and silica was observed with depth, time and also with distance from the fjord sill, indicating an aging of the water masses with time from our first sampling, as well as older water at the head of the fjord.

360 THURSDAY 12 SEPTEMBER 2013, 17:30 PS-10. Microbial autoecology and coevolution

PS-10.22. IMPLICATIONS OF THE IMPACT OF VIRUSES ON THE BACTERIAL COMMUNITY IN THE LARGEST LAGOON IN EUROPE

Sigitas Sulcius, Klaipeda University, Coastal Research and Planning Institute, Klaipeda (Lithuania) Coauthors: Lindroos A, Staniulis J, Paskauskas R, Leskinen P

Virus predation is the major cause of bacterial mortality in highly productive estuarine environments. However, high viral abundance in these aquatic ecosystems does not imply high infection and/or virus production rates. In addition, host availability, community composition and activity in estuarine is strongly modified by environmental factors such as freshwater and seawater mixing or water residence time, in turn limiting both density- and trait-dependent virus- host interactions. Therefore, differences in bacterial community along estuarine gradient can lead to the prevalence of distinct virus-host system, and possibly different types of virus-host interactions. The present study aimed to identify the relation between different viral parameters and bacterial community properties and mortality across environmental gradient of the Curonian Lagoon (South- Eastern Baltic Sea). We found that total virus mediated bacterial mortality is limited by virus loss rates and host abundance. We also observed significant differences in virus burst size and discuss these changes in the context of virus burst size control hypotheses. We suggest that virus - host interactions in the highly productive coastal environment is both virus and bacteria density-dependent process, as opposite to trait mediated interactions (lysis vs lysogeny) in oligotrophic regions of marine waters. This study is also the first attempt to quantify microbial diversity and virus production rates in the largest lagoon in Europe.

361 THURSDAY 12 SEPTEMBER 2013, 17:30 PS-10. Microbial autoecology and coevolution

PS-10.23. THE MECHANISMS INVOLVED IN CHEMOTAXIS AND MOTILITY DURING INFECTION ONSET IN V. CORALLIILYTICUS

Karina Winn, Flinders University of South Australia & Australian Institute of Marine Science, Twonsville, Queensland (Australia) Coauthors: Bourne DG, Mitchell JG

Vibrio coralliilyticus is a known coral pathogen of ecological importance for the health of coral reefs worldwide and it is responsible for disease outbreaks globally. Fundamental to understanding the pathogenesis and virulence of this microorganism is infection initiation by motility and chemotaxis, which controls the potency and speed of infection. Analyzing the motility behavior of V. coralliilyicus in natural coral mucus as well as in highly viscous control liquids to mimic natural environmental fluctuations determines the impact environmental changes have on the flagella-mediated bacterial motility. Currently there is little known about the motility response of V. coralliilyticus to environmental fluctuations including temperature, nutrient addition and fluid properties. Using a three-pronged approach that incorporates bioinformatics, gene expression analysis and microscopy, this project examined the motility mechanisms of this pathogenic microorganism. Searching strategies were analyzed in Vibrio coralliilyticus BH1 strain, using microscopy and video tracking. 3-step flick search patterns (‘flicks’) were 1.4x more frequently found in oxygenated environments than in areas of depleted oxygen (P = 0.006). Moreover, straight swimming search patterns were 14x more frequently utilized in viscous solutions greater than 21 centipoise (cP) than other search patterns. Only one flick search pattern was identified in viscosities above 1.3 cP and on average 2 run and reverse search patterns were identified in viscosities above 1.3 cP. The velocity of search patterns was shown to increase in liquids up to 1.7 cP before decreasing in liquids greater and including 2 cP. The biosynthesis protein, FlhA and flagellar protein FlaA were analyzed across differing temperature and chemical gradients to simulate environmental seawater changes due their influential nature on the motility of V. coralliilyticus with results showing that nutrient concentration impacts the degree of upregulation of these flagellar proteins. This study suggests that the presence or absence of nutrients, temperature fluctuations and oxygen gradients within a coral during diurnal and nocturnal hours influences not just the physical motile response of V. coralliilyticus but also the response on a gene level.

362 THURSDAY 12 SEPTEMBER 2013, 17:30 PS-10. Microbial autoecology and coevolution

PS-10.24. DIVERSITY OF CYANOPHAGES AND ALGAL VIRUSES IN TWO DEEP AND LARGE PERI- ALPINE LAKES

Zhong Xu, Coauthors: Jacquet S

Cyanobacteria and eukaryotic microalgae are important players in the functioning of aquatic ecosystems. Among key regulating factors, viruses are now recognized as one of the main forces intervening in the regulation of these phytoplankton communities. However, the knowledge about the dynamics and diversity of phytoplanktonic viruses (i.e. the cyanophages and mainly the phycodnaviruses) is still scarce, and this is particularly true for large and deep lakes for which little information has been made available until now. In 2011, we conducted a one-year survey in the two largest French lakes (i.e. Lakes Annecy and Bourget) and studied viral community abundance, richness and diversity using flow cytometry, qPCR, PCR-DGGE, PFGE and cloning-sequencing approaches. Both and phycodnavirus signature genes examined (i.e. g20, psbA, mcp, polB) were very diverse and prevalent in alpine lakes. Viral community compositions were significantly different between the two lakes and clear differences were also observed with other environments, either marine or freshwater, indicating unique feature of peri-alpine lakes. The cyanophage community was dominated by viruses infecting Synechococcus spp., while the phycodnavirus community was mainly represented by viruses related to Chlorophyta and Prymnesiophyceae. These viral populations varied month after month in each lake, likely in response to shifts in host community and/or environmental factors. Also, only a few genotypes persisted throughout the year. These original results suggested the existence of seed-bank population for phytoplankton viruses in French peri-alpine lakes with representatives that are likely to become numerically important when their host abundances become dominant or at least reach appropriate levels to be infected, likely in response to favorable environmental conditions. Some parallel experiments allowed us to confirm that cyanophages could be important killers of the picocyanobacterial community at some periods of the year and a key driver in host population structure.

363 THURSDAY 12 SEPTEMBER 2013, 17:30 PS-S1. Ecology of waterborne pathogens in the light of climate change

PS-S1.01. MOLECULAR MONITORING FOR PATHOGENIC EUKARYOTIC MICROBES IN LAKE WATER

Maria Cristina Angelici, Istituto Superiore di Sanità, Rome (Italy) Coauthors: Ade P, Funari E

The role that inland surface waters have in the transmission of several protozoan parasites infection has been revealed since several years. In the United States and in Europe (England) outbreaks with severe gastrointestinal symptoms have been caused by usage of surface fresh water for drinking or for bathing. Outbreaks of giardiasis or cryptosporidiosis of high entities have been due to contaminated water by the fecal-oral route of transmission. The environmental conditions which favor these infections may be easily identifiable and climatic changes have recently highly increased these microbes spread. New species of eukaryotic microbes have appeared in temperate environment and new biological cycles more complicated than before have been identify for pre-existing species. This study is carried out to examine a volcanic lake near Rome which water is used in summer to supply two small towns by drinking water. The basin is used also for recreational purpose in summer. We performed a molecular analysis of the lake water sampling each month in a year in different sites including two bathing stations. Twelve different protozoa parasites species were monitored in the lake water by specific PCR amplification using also specific primer for genetic assemblages and strains. Some of that are recently considered as emergent parasites. Giardia duodenalis, Blastocystis sp. and Toxoplasma gondii DNA was amplified by the water samples showing the presence of different zoonotic cycles and risk factors for people. The lake is normally used to graze livestock of different species, particularly in winter, autumn and spring but the access of animals to the lake is interdicted in summer during the summer season. A risk for infection is present just when the zoonotic cycle of the parasite is maintained but the touristic population is in a certain sense under control. The sediments role must to be better studied.

364 THURSDAY 12 SEPTEMBER 2013, 17:30 PS-S1. Ecology of waterborne pathogens in the light of climate change

PS-S1.02. SPREAD OF PACIFIC NORTHWEST VIBRIO PARAHAEMOLYTICUS OUTBREAK CLONE TO THE ATLANTIC COAST OF THE UNITED STATES AND SPAIN

Craig Baker-Austin, Centre for Environment, Fisheries and Aquaculture Science, Weymouth (UK) Coauthors: Martinez-Urtaza J, Jones JL, Newton AE, Gonzalez-Aviles GD, De Paola A

Globally, Vibrio parahaemolyticus (Vp), is a leading cause of seafood-associated gastroenteritis. Historically, the Vp serotypes O4:K12 and O4:K untypable, which have been shown to be more virulent than other pathogenic Vp strains, have been unique to the US Pacific Northwest region (PNW). These strains, first identified in the PNW in 1988, caused large US outbreaks in 1997 and 2006 linked to consumption of Pacific shellfish, but have not been linked to outbreaks outside of the PNW until now. During the summer of 2012, Vp outbreaks caused by these serotypes occurred in both the Atlantic Coast of the US and Spain. The US Centers for Disease Control and Prevention (CDC) received reports of 28 cases of infection from 9 states, and regional health authorities in Galicia (Xunta de Galicia, NW Spain) received reports of 51 illnesses of which 9 cases were subsequently laboratory-confirmed. The US outbreak was linked to consumption of shellfish harvested from Oyster Bay Harbor, New York between April and August, 2012. The Spanish outbreak occurred in August 2012 on a cruise ship in Galicia, Spain and was epidemiologically linked to cooked seafood cooled using ice produced from untreated local seawater. Clinical isolates from US and Spanish cases were highly similar to PNW strains by serology, PCR for virulence factors, pulsed-field gel electrophoresis (PFGE), and multi-locus sequence typing (MLST). The initial arrival, overall environmental distribution, and mechanism for the introduction of this Vp strain to the Atlantic Coasts of the United States and Spain are unknown. However, importation and storage of live contaminated bivalve shellfish in local waters, ballast water movement, and long distance oceanic transportation of strains into new regions are possible mechanisms. Both New York and Galicia have previously experienced large Vp outbreaks caused by other strains and are near major ports. Both the US and Spanish outbreaks corresponded temporally and spatially with higher than normal surface seawater temperatures, which has been associated with both an increase of environmental prevalence of Vp and illnesses. It is uncertain if these strains will persist or spread to other regions. We advocate continued and improved national and international collaboration and data sharing to help recognize and respond to future Vp outbreaks

365 THURSDAY 12 SEPTEMBER 2013, 17:30 PS-S1. Ecology of waterborne pathogens in the light of climate change

PS-S1.03. PREDICTIVE MODELING OF FAECAL INDICATOR LOADS IN TWO GERMAN RIVERS

Simone I Böer, Federal Institute of Hydrology, Koblenz (Germany) Coauthors: Herrig I, Brennholt N

Global warming and involved changes in local climate are predicted to affect patterns, intensities and duration of precipitation and droughts in Central Europe, thus particularly influencing aquatic ecosystems. More frequent extreme weather situations such as heavy rain and flood events could temporally increase the input of enterobacteria from point and non-point sources into rivers, leading to a deterioration of the water quality. Although rivers in Germany play an important role in terms of transport, drinking water supply, use in irrigated agriculture and recreation, quantification of faecal bacteria is usually not included in river monitoring programs, making it difficult to project future bacterial loads. This is partly due to the fact that microbiological water quality can change rapidly in rivers, thus punctual measurements are generally only snap-shots of their hygienic status. In the present study, faecal indicators (E. coli, intestinal enterococci, bacteriophages) were quantified weekly for 1 year at 2 river sites, one in the river Rhine (free- flowing) and one in the river Moselle (impounded). Simultaneously, hydrometeorological and physico-chemical parameters were collected. Correlation analyses were conducted in order to temporally synchronize the contextual data and to identify those parameters with the best explanatory power. Climate-sensitive factors such as global solar irradiation, rainfall and water discharge proved to be strongly related to bacterial loads and were identified as particularly suitable for predictive modelling of faecal indicators at these two sites. The results of the ongoing analyses will be presented at the conference.

366 THURSDAY 12 SEPTEMBER 2013, 17:30 PS-S1. Ecology of waterborne pathogens in the light of climate change

PS-S1.04. POTENTIALLY PATHOGENIC VIBRIO SPP. IN GERMAN COASTAL AND ESTUARINE REGIONS AND THEIR SENSITIVITY TO CLIMATE CHANGE

Nicole Brennholt, Federal Institute of Hydrology, Koblenz (Germany) Coauthors: Hauk G, Heinemeyer EA, Luden K, Duty O, Janssen F, Böer SI

Within the research program KLIWAS one project focuses on the expected consequences of climate change on water hygiene, especially distribution and transport of potentially pathogenic Vibrio spp., and their survival and growth. Vibrio spp. are ubiquitous bacteria in estuarine and sea water environments, which can cause primary or secondary septicaemia. In Germany severe Vibrio-related human infections after contact with sea water are known since 1994. Ever since, outbreaks of Vibrio-related wound infections have been reported for the Baltic Sea coast following summer heat waves. For the more saline waters of the North Sea, only single cases of Vibrio- related wound infections have been reported in the recent past. Although concern is growing that Vibrio infections may become an emerging disease in Northern European coastal waters particularly with regard to climate change, there is only insufficient knowledge of the ecology of vibrios and their health risk potential in these regions. Therefore, two independent monitoring studies were carried out at the German North and Baltic Sea coast. Along the North Sea coastline and within the Ems and Weser estuaries, samples were taken monthly at 10 sites over a 2-year period. At the Baltic Sea coastline, samples from 12 sites were analysed in the course of 6 sampling campaigns. In order to determine the driving factors governing the occurrence and distribution of potentially pathogenic Vibrio spp., bacterial analyses in water and sediment were accompanied by the measurement of a broad range of biotic as well as physico-chemical parameters. Aim of both studies was to investigate seasonal variations of Vibrio spp. (V. vulnificus, V. parahaemolyticus, V. alginolyticus, and V. cholerae) in these two ecosystems, to identify environmental parameters that promote Vibrio spp. presence and to identify possible “hot spots” of potentially pathogenic Vibrio spp. (particularly V. vulnificus) in German coastal waters. Our results show that the Vibrio spp. community structure in the German North and Baltic Sea differ quite considerably despite mutual behaviour towards temperature and salinity, suggesting that additional factors play an important role for Vibrio spp. ecology. In both study areas sediment vibrios were consistently more abundant than those in the water and more resistant towards low temperatures. Thus, sediments seem to serve as a potential hideaway and reservoir for these organisms in winter. In conclusion, elevated Vibrio spp. abundances at high temperatures suggest that climate change effects may potentially influence Vibrio spp. distribution in German coastal waters and increase the risk of Vibrio-related wound infections by contact with sea water and sediment. Thereby regional differences in Vibrio spp. occurrence should be taken into account.

367 THURSDAY 12 SEPTEMBER 2013, 17:30 PS-S1. Ecology of waterborne pathogens in the light of climate change

PS-S1.05. USING BACTERIOPHAGES TO CONTROL MARINE FISH PATHOGEN

Cagatay TI, Akdeniz University, Faculty of Fisheries, Basic Sciences Division, Campus, Antalya (Turkey)

Vibriosis disease is an acute to chronic infection caused by Vibrio anguillarum and Vibrio harvei. Many commercially important fish species are affected by vibriosis such as channel catfish (Ictalurus punctatus Rafinesque), common carp (Cyprinus carpio Linnaeus), rainbow trout (Oncorhynchus mykiss Walbaum), eels (Anguilla sp.), tilapia (Oreochromis spp.) and ornamental species-goldfish (Carassius auratus Linnaeus), sea bass (Dicentrarchus labrax) and sea bream (Sparus aurata). In aquaculture settings, vibriosis outbreaks are often related to environmental stress associated with high stocking densities, increased feeding rates, elevated organic loads and high temperatures. Therefore, it is quite important to prevent and then treat diseases before economical losses. Recent studies shows that bacteriophages can be used as biocontrol agents for bacterial infections in marine aquaculture. Although chemotherapy, vaccination, usage of probiotics are methods to treat or prevent bacterial infections, bacteriophage therapy can provide an alternative and an enviromental friendly approach in treating fish diseases. In our study, we isolated and characterized Vibrio-specific phages to control this disease in sea bass (Dicentrarchus labrax). We have isolated and identified two lytic Vibrio bacteriophages (PVc-1 and PVc-2) by looking their genomic sizes. We used these PVc-1 and PVc-2 phages to show decrease in experimantal V. anguillarum and Vibrio harvei infection in sea bass. Our results supports the development of phage as a valid alternative for control of this disease in aquaculture.

368 THURSDAY 12 SEPTEMBER 2013, 17:30 PS-S1. Ecology of waterborne pathogens in the light of climate change

PS-S1.06. PRESENCE AND CO-SELECTION OF ERYTHROMYCIN AND COPPER RESISTANCE IN AN ENTEROCOCCUS HIRAE ISOLATE FROM MARINE SEDIMENT

Andrea Di Cesare, Università Politecnica delle Marche, Ancona (Italy) Coauthors: Pasquaroli S, Vignaroli C, Paroncini P, Biavasco F

The global spread of antibiotic resistance is a topical issue. Heavy metal pollution can co-select for genetic element carrying both heavy metal and antibiotic resistance traits. Metal resistance can thus contribute to the persistence of antibiotic resistance. Recent data have documented antibiotic resistance in the marine environment. An enterococcal strain isolated from coastal marine sediment collected in front of an oil refinery was characterized by high-level resistance to erythromycin (MIC>256 µg/ml), copper and cadmium (both MIC 25 mM). Identification to the genus and species level and PCR analysis for erythromycin [erm(A), erm(B), and mef], copper (tcrB), and cadmium (cadA) resistance genes showed it to be an Enterococcus hirae strain carrying all the resistance genes tested except cadA. The transfer potential of erm(A), erm(B), mef, and tcrB was evaluated by filter mating using Enterococcus faecalis JH2-2 fus rif as the recipient. Moreover, enterococcal conjugative plasmids pRUM, pRE25, and pHTβ were sought by rep-targeting PCRs. Erythromycin-resistant transconjugants were obtained with a frequency of 4.3 x 10-7/recipient; 20 were further analyzed for plasmids and resistance genes along with the donor. All were found to carry a pRE25 plasmid as well as erm(B) and tcrB, demonstrating a physical association between these two genes. This is the first report of an antibiotic- and heavy metal-resistant E. hirae strain isolated from the marine environment. The present data also i) provide evidence for the co- transfer of antibiotic and heavy metal resistance genes, likely through the conjugative plasmid pRE25, and ii) document the possible selection for antibiotic resistance traits by heavy metals in the marine environment and the possibility of their transfer from environmental isolates to E. faecalis, the species most frequently involved in human infections.

369 THURSDAY 12 SEPTEMBER 2013, 17:30 PS-S1. Ecology of waterborne pathogens in the light of climate change

PS-S1.08. PRODUCTION OF A SECRETED PROTEASE BY VIBRIO CHOLERAE IN ENVIRONMENTAL MIXED SPECIES CONSORTIA ON CHIRONOMID EGG MASSES

Malka Halpern, Department of Biology and Environment, University of Haifa, Oranim, Kyriat Tivon (Israel) Coauthors: Atamna-Ismaeel N, Bernardy E, Hammer BK

Vibrio cholerae causes cholera diarrhea, but is also a natural inhabitant of aquatic ecosystems where it can associate with copepods and with chironomids. We commonly isolate V. cholerae along with other bacteria from all four chironomid life stages: eggs, larvae, pupae (aquatic stages) and adults (caught in the air). Because chironomid populations and the V. cholerae in their egg masses exhibit host–pathogen population dynamics, we hypothesized this relationship is possible because V. cholerae degrades the gelatinous matrix of chironomid egg masses to acquire nutrients and in doing so prevents egg hatching. The secreted V. cholerae Haemagglutinin Protease (HAP), is required for egg mass degradation. It has been shown previously in a few clinical V. cholerae strains that HAP is activated by Quorum Sensing (QS) signals. The aim of the current research was to define the role of QS autoinducers (AI) signals in the production of HAP by V. cholerae in environmental mixed species. Chironomid endogenous bacteria were isolated and examined for AI-2 secretion and their capacity to induce HAP production by V. cholerae within a mixed species consortium. We found that V. cholerae O1 ∆luxS, ∆cqsA mutant (which is unable to produce AIs) responds to AIs produced by other members of the chironomid bacterial consortium by expressing the hapA gene. This study elucidate the role of chironomid endogenous bacterial QS and its impact on V. cholerae. By understanding V. cholerae QS signals in the insect system we may uncover the interactions between this pathogen and the human gut.

370 THURSDAY 12 SEPTEMBER 2013, 17:30 PS-S1. Ecology of waterborne pathogens in the light of climate change

PS-S1.09. LEGIONELLA SPP. PREVALENCE IN A DRINKING WATER SYSTEM IN ISRAEL

Malka Halpern, Department of Biology and Environment, University of Haifa, Oranim, Kyriat Tivon (Israel) Coauthors: Rodríguez-Martínez S, Sharaby Y, Pecellin M, Brettar I, Höfle M

Bacteria of the genus Legionella cause waterborne infections, resulting in severe pneumonia. In order to advance the current knowledge on the ecology of Legionella in drinking water, the presence of Legionella in a drinking water system in Israel was monitored. Seven sampling points (A-G) were selected inside Oranim College (Tivon, Israel) in order to cover the drinking water system route inside the Campus. Legionella was isolated from most of the sampling points and from cold or hot water and biofilms. The prevalence of Legionella in different seasons was between 56%-78% and 29%-71% in the water and the biofilm samples, respectively. Legionella counts in the water samples ranged from 1.0x101 to 5.7x103 cfu/l. No significant differences were found between Legionella counts in different seasons. Significant positive correlation was found between Legionella and heterotrophic total counts. L. pneumophila serogroup 3 was isolated at the eastern side of the campus (points A-B) while L. pneumophila serogroup 1 was isolated in all the sampling points at the west side of the campus (points C-G). Two different species were isolated at point E (L. pneumophila and L. sainthelensis). Legionella virulence genes (mip, dotA, flaA) were detected in all the isolates. Significant negative correlation was found between Legionella counts and chlorine levels indicating that higher levels of chlorine may reduce Legionella occurrence. We conclude that the water system at Oranim campus is completely infected with Legionella. A risk assessment should be performed in order to minimize health problems.

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PS-S1.10. COUPLING BETWEEN NUTRIENT RICHNESS AND OCCURRENCE OF POTENTIALLY PATHOGENIC BACTERIA IN AQUATIC SYSTEMS

Peter Mathisen, Department of Ecology and Environmental Science, Umeå (Sweden) Coauthors: Thelaus J, Sjödin A, Forsman M, Andersson A

Anthrophogenic activities and climate change influence aquatic systems, for example by causing increased temperature and elevated inflows of nutrients from drainage areas. Most of these changes tend to drive aquatic systems towards eutrophication. According to previous experimental studies, high nutrient richness leads to a selection for predation-resistant forms of bacteria, capable of surviving in association with protozoa. This may in turn favor the persistence of potential pathogens with an intracellular lifestyle. However, specific environmental factors that favor the persistence of pathogenic bacteria such as , , and are yet to be fully established. Temperature and nutrient availability are often discussed as important variables. We hypothesized that an increase in nutrient availability selects for predation-resistant and potentially pathogenic bacteria through elevated predation-pressure on the bacterial community. Only a few previous studies focus on the possible coupling between water properties and the presence of potential pathogens in the environment. To further elucidate these relationships we sampled 19 aquatic systems along a productivity gradient in southern Sweden at the end of summer 2012. We analyzed several parameters as determinants of nutrient status as well as the bacterial, protist and phytoplankton biomass and community composition with the aim of pinpointing factors that shape the bacterial community and favor the persistence of potential pathogens. The bacterial and eukaryotic community compositions of each lake were defined using universal 16S-V4 (Bacteria and Archea, 515f-806r) and 18S-V9 (eukaryotes, 1391f-EukBr) PCR primers and Illumina MiSeq sequencing. Our chlorophyll-a concentration data varied from 1-90 µg/l, showing that the sampled aquatic systems ranged from oligotrophic to hyper-eutrophic across the gradient and a principal coordinate analysis showed that bacterial communities differed in oligotrophic and eutrophic waters. Furthermore, bacterial species richness was also higher in eutrophic waters and genera representing potentially pathogenic and environmental taxa were identified.Vibrio choleraeFrancisella tularensisLegionella pneumophila.

372 THURSDAY 12 SEPTEMBER 2013, 17:30 PS-S1. Ecology of waterborne pathogens in the light of climate change

PS-S1.11. NOROVIRUS IN URBAN SURFACE WATERS DURING TWO CONSECUTIVE WINTERS WITH RAPIDLY DECREASING TEMPERATURE

Kira Moon, Seoul National University (South Korea) Coauthors: Lee H, Kwon M, Kim SJ

Noroviruses (NoVs) cause acute gastroenteritis globally, mainly from October to March. In the winter of 2012 to 2013, outbreak of new variant NoV GII4 was reported around the world. NoV infections have significantly increased in Korea as well by 88.5% and 67% of the reported cases were identified to be caused by new variant type, NoV GII4, Sydney type (Accession number: JX459908.1). The winter of 2012 in Korea was exceptionally cold that the average air temperature from November 2012 to March 2013 was 0.34°C, compared to the average air temperature of 2.26°C in the last 30 years. We have monitored two surface waters located at the Seoul Metropolitan area, during two winter seasons from November 2011 to March 2013 and collected 38 samples. The samples were collected on two-week intervals from 2012 to 2013 from four different selected sites. Water temperatures were measured on site, and the data for air temperatures were retrieved from the Korean Meteorological Administration. Specific data sets with similar sampling periods as previous year were chosen from 2012 to be compared. When NoV detection rates and its distributions were compared with the 2012 data, the concentration of the NoV increased up to 457 folds, while the air temperature decreased by 3.4 to 5.6°C at most. From the 2012-2013 data alone, negative correlation between NoV concentration and water and air temperature was observed (r=0.60 and 0.48, respectively). These results indicate that the lower temperature may cause increase in NoV in the environment, thereby increasing the possibility of infections through water transmission routes, such as irrigational, recreational, and drinking waters, as confirmed in our previous studies. NoVs were detected from 7 of 32 samples (21.9%) by conventional RT-PCR, and the NoV in all of them were identified as the NoV GII4 Sydney type. Considering that a NoV type that were epidemic in Korea prior to 2012 was NoV GII4 P 2009 New Orleans type, when new variant is apparent, that specific strain seems to outnumber the previously epidemic strains. We have observed the short-term events that during rapid changes of air temperature, NoV occurrence and its concentration in water environments could be affected as well. Therefore, in a long-term perspective, continuous monitoring on NoV behaviors in aquatic environments is needed as more new variant NoVs types and more weather shifts are expected to occur.

373 THURSDAY 12 SEPTEMBER 2013, 17:30 PS-S1. Ecology of waterborne pathogens in the light of climate change

PS-S1.12. BACTERIAL COMMUNITIES AND THEIR PATHOGENIC POTENTIAL ALONG A POLLUTION GRADIENT IN A TROPICAL WATERSHED IN TANZANIA

Douglas Mushi, Helmholtz Centre for Infection Research, Braunschweig (Germany) Coauthors: Pereira R, Höfle M, Brettar I

Climate change is considered to strongly affect water quality in sub-Saharan Africa. However, knowledge about bacterial communities and their pathogenic potential is very limited for tropical river ecosystems. In addition, assessment of the state of fecal pollution is not feasible, because monitoring with indicator bacteria such as E. coli or total coliform developed for temperate climate fail for tropical environments. To overcome these constraints and to improve our understanding of the ecology of enteric pathogens and their source in tropical environments, we analyzed water samples from tropical river system in Mororgoro, Tanzania (6.82oS and 37.66oE) encompassing wide catchment gradient (from pristine to highly polluted agriculture and/or urban). This river system is the source of drinking water for Morogoro town as well as Dar es Salaam City in Tanzania. Water samples were aseptically collected from each pristine, urban and agriculture sites during the dry and wet period. Water samples were analyzed for chemo-physical (nutrients, chloride, BOD5, total suspended solids, dissolved oxygen, temperature) and bacteriological (total bacterial counts (TBC), heterotrophic plate counts (HPC), CFU on Endo agar) parameters using standard methods. In addition, the bacterial biomass of river water samples was harvested and analyzed with respect to the total bacterial community and phylogenetic subsets (such as Enterobacteriaceae and Bifidobacteria) of conceivable value for distinction of fecal pollution and tracking the source of pathogens. The data showed a pronounced correlation between the physico-chemical- and the bacteriological- parameters, i.e. the urban and agricultural polluted samples could be clearly distinguished (by PCA analyses) from the pristine river water by increased nutrient concentrations and increased bacterial numbers (total counts, HPC and CUFs on Endo agar). A comparison of the river water characteristics with the bacterial communities retrieved directly from river water and those retrieved from Endo-agar was achieved. This comparison aims to assess the potential of bacterial species that can indicate fecal pollution. The constraints and potential of single species or bacterial communities as indicators for fecal pollution in tropical environments will be addressed with respect to their value for public health information and in the light of climate change.

374 THURSDAY 12 SEPTEMBER 2013, 17:30 PS-S1. Ecology of waterborne pathogens in the light of climate change

PS-S1.13. ISOLATION AND CHARACTERISATION OF PANDEMIC VIBRIO PARAHAEMOLYTICUS STRAINS IN UK SHELLFISH AND WATER SAMPLES

Andy Powell, Centre for Environment, Fisheries and Aquaculture Science, Weymouth (UK) Coauthors: Baker-Austin C, Stockley L, Wagley S, Hartenell R

Vibrio parahaemolyticus is a Gram-negative, halophilic bacterium found commonly in temperate and warm estuarine waters worldwide. Vibrio parahaemolyticus is considered an emerging bacterial pathogen in Europe, and has been responsible for several recent seafood-associated outbreaks. During ad hoc testing of raw shellfish produce in May 2012, pandemic group (O3:K6) Vibrio parahaemolyticus were isolated from Pacific oysters, Crassostrea gigas, harvested in Southern England. Follow-on testing of water and shellfish, encompassing a small number geographically diverse sites, also retrieved pandemic group isolates. Preliminary molecular analyses including PFGE and MLST strains isolated in 2012 and 2013 indicates that these bacteria may represent novel isolates when compared to other pandemic V. parahaemolyticus strains in Europe. These strains are amongst the most northerly pandemic strains described to date, and represent the first instance of pandemic V. parahaemolyticus isolated in the UK, highlighting the expanding geographical distribution of these foodborne pathogens in the environment. The isolation of pandemic group strains from temperate environmental sources highlights the potential for temperature abuse of raw shellfish produce as a potential risk factor, as implicated in past outbreaks caused by pandemic strains in Europe. Future work should include a quantitative surveillance analysis of the seasonal and geographical distribution of these pathogens in unpurified bivalve shellfish in the UK and potentially elsewhere in Northwest Europe.

375 THURSDAY 12 SEPTEMBER 2013, 17:30 PS-S1. Ecology of waterborne pathogens in the light of climate change

PS-S1.14. ESCHERICHIA COLI ASSOCIATED WITH MACROALGAE IN THE VENICE LAGOON

Grazia Marina Quero, Institute for Marine Science - National Research Council (ISMAR-CNR) (Italy) Coauthors: Luna GM

The surface of marine macroalgae host an abundant and diverse array of bacteria, with abundance up to 107 cells cm-2 depending on the algal species, thallus section and season. Some authors have recently introduced the “holobiont” concept, suggesting that seaweeds and associated microbes act as a unified functional entity. In polluted areas, epibiotic microbes may include potentially pathogenic bacteria of fecal origin, as the algal surface can represent a more favourable environment for bacterial survival than the overlying waters. However, little is known about the ecology of attached fecal bacteria, their genetic diversity and the interactions between algae and bacterial populations. We hypothesize that seaweeds may promote the survival of attached E. coli, and that algae are reservoirs of genetically-distinct bacterial lineages. We collected macroalgal (Ulva spp., Undaria spp. and Sargassum spp.) and water samples in three sites located in the Venice lagoon, selected along a putative gradient of fecal contamination. Samples were collected to i) quantify Escherichia coli attached to the macroalgae as opposed to the overlying water; ii) describe the genetic diversity of the isolates; iii) perform laboratory experiments to investigate whether macroalgae may favour their growth and persistence. About 400 isolates were screened by molecular tools for their identification as E. coli, the assignment of the phylogenetic group, the potential association with the recently described cryptic and environmentally-adapted clades, and the genotypic diversity. Attached E. coli populations were abundant and genetically diverse, and included extra-intestinal and potentially pathogenic strains. Most of attached E. coli were able to grow on macroalgal extracts as the only source of carbon. No patterns were observed when the abundance of attached bacteria was compared with that in the surrounding waters. Algal and water populations did not show temporal-, spatial-, habitat- or phylogroup-dependent patterns, suggesting that the relationship between E. coli and macroalgae may be casual. Our results suggest the existence of an environmental reservoir of E. coli genotypes, which possibly includes “naturalized” populations adapted to the macroalgal habitat, with implications from either the public health and ecological perspective.

376 THURSDAY 12 SEPTEMBER 2013, 17:30 PS-S1. Ecology of waterborne pathogens in the light of climate change

PS-S1.15. IDENTIFICATION OF NON-TUBERCULOUS MYCOBACTERIA RESERVOIRS IN URBAN LAKES FACING GLOBAL CHANGE PRESSURES

Adelaide Roguet, LEESU, Creteil (France) Coauthors: Therial C, Boudahmane L, Saad M, Moulin L, Lucas FS

Non-tuberculous mycobacteria (NTM) are considered to be opportunistic human pathogen. These hydrophobic bacteria are widespread in the aquatic environments. Since they can proliferate in various conditions, from low organic carbon water to more complex biofilms, freshwater environments represent an important source of contamination for human populations. Most studies treat NTM densities and species composition in drinking water distribution network whereas fewer studies have focused on surface waters, mainly in streams or rivers. Although lakes provide important recreational activities that could be impaired by variety of pathogens, very few studies were conducted on them. Consequently, a better understanding of the density and composition of NTM within lakes is necessary, especially in the context of global change, where eutrophication of lakes could switch nutrient supply o r affect biotic interactions. In order to (1) identify which habitats are favorable for NTM occurrences within lakes and to (2) evaluate the impact of eutrophication on NTM, two contrasted urban lakes with different trophic status were monitored during summer and autumn. One lake is mesotrophic with for example 15.94±2.53 μg of chlorophyll a L-1 in the summer whereas the other is eutrophic with 49.14±8.68 μg L-1. Five compartments were surveyed per lake: wat er column, neuston, sediment and epiphytic and epilithic biofilms. For each compartment, NTM densities were quantified by a specific quantitative PCR. For instance, NTM concentration is about 9.1±6.7x102 copies L-1 in the water column and 3.9±3.5x103 copies L-1 in the neuston. Statistical analyses were also conducted by comparing biological results with physico-chemical measurements. Results will be discussed.

377 THURSDAY 12 SEPTEMBER 2013, 17:30 PS-S1. Ecology of waterborne pathogens in the light of climate change

PS-S1.16. IDENTIFICATION OF BACTERIAL POPULATIONS IN STERLET BY THE METHOD OF 16S RDNA GENE SEQUENCING

Yuriy Rud, Institute of Fisheries, Kyiv (Ukraine)

Bacteria are probably the most significant pathogens of cultured fish, causing the high levels of morbidity and mortality. The rapid development of the aquaculture industry has led to a highly motivated understanding of the pathogenesis of bacteria causing disease in farmed fish. But information about bacterial flora and impact of bacteria on fish organisms remains relatively poor compared with our understanding of bacterial diseases in humans and other animals. Therefore the aim of the present study was to identify and isolate the bacterial populations in sterlet Acipenser ruthenus using the methods of PCR and direct sequencing. For bacterial examination of starlet fingerlings the samples of skin, gills and internal organs were collected and propagated in Trypticase soy agar at 28° C for 18 hours. The grown columns were tested by microscopic examination and each independent column was used for DNA extraction. Bacterial genomic DNA was extracted using a phenol:chloroform mixture, followed by ethanol precipitation. The multiplex PCR (mPCR) of pathogenic bacteria was used for preliminary identification. For amplification of full length bacterial 16S rDNA gene the set of oligonucleotide primers disigned by Lane et al. (1991) was used. Sequencing was performed on a 3130 Genetic Analyzer (Applied Biosystems) and analyzed using BLASTN and DNA-STAR 5.05 software. The mPCR identified strains of Aeromonas hydrophila and Flavobacterium columnare, two PCR products of about 700 and 200 bp respectively were visible on agarose gels stained with ethidium bromide. After 35 cycles of bacterial genomic DNA amplification, an each fragment of 16S rDNA gene was selected for sequencing. In present study the agents of bacterial infectious diseases and non-pathogenic bacteria from genus Flavobacterium, Aeromonas, Pseudomonas, Yersinia, Acinetobacter and Citrobacter were isolated and identified.

378 THURSDAY 12 SEPTEMBER 2013, 17:30 PS-S1. Ecology of waterborne pathogens in the light of climate change

PS-S1.17. SIMPLE AND SENSITIVE DETECTION OF THE 18S rRNA GENE FROM CRYPTOSPORIDIUM PARVUM OOCYSTS BY SURFACTANT EXTRACTION TREATMENT

Takahiro Sekikawa, University of Shizuoka (Japan)

Detection of Cryptosporidium oocysts in raw water sources is considered an important component in the management, prevention and control of Cryptosporidium in drinking water supplies. Cryptosporidium is an intestinal protozoan parasite and causes waterborne gastrointestinal disease worldwide. It has a robust oocyst, which is resistant to many environmental factors as well as to normal water disinfection processes. Successful detection and characterization of Cryptosporidium oocysts usually requires freeze-thaw cycling, enzyme and surfactant treatments, and DNA purification in order to extract DNA from the robust oocyst. However, such procedures are complicated and often result in the loss of target DNA. The anionic surfactant sodium dodecyl sulfate (SDS) has been generally used to extract DNA from many different organisms but it inhibits DNA polymerase at extremely low concentrations. As an alternative to these complicated procedures, we have established surfactant extraction treatment (SET) that can extract DNA from Cryptosporidium parvum using only SDS and the nonionic surfactant Tween 20. This study discusses the detection of the 18S rRNA gene from C. parvum oocysts by SET and reverse transcription loop-mediated isothermal amplification (RT-LAMP) as the amount of target rRNA is known to be much larger than that of target rDNA. LAMP is a nucleic acid amplification method that amplifies specific nucleotide sequences with four or six primers under isothermal conditions. We evaluated the inhibition of AMV reverse transcriptase and Bst DNA polymerase by the addition of SDS or Tween 20 in one-step RT-LAMP. RT-LAMP was inhibited at the concentration of 0.1% SDS using one oocyst per test tube, whereas it was not inhibited by even 5% of Tween 20. Subsequently, we examined the ability of Tween 20 to suppress the RT-LAMP inhibition, and the inhibition induced by SDS was suppressed by the addition of 5% of Tween 20. Consequently, we succeeded in detecting 10-3 oocysts per test tube, without DNA purification, by SET and RT-LAMP. This data proves that SET can be used for the sensitive detection of the 18S rRNA of C. parvum.

379 THURSDAY 12 SEPTEMBER 2013, 17:30 PS-S1. Ecology of waterborne pathogens in the light of climate change

PS-S1.19. FAECAL INDICATOR BACTERIA IN COMBINED SEWER OVERFLOW AND IN THE SEINE RIVER

Claire Therial, LEESU, Université Paris Est Créteil (France) Coauthors: Lucas FS, Lesage L, Rocher V, Goncalves A, Servais P, Mouchel JM

Urban sewer overflows are becoming a major source of microbiological contamination of surface waters since the other point sources are more and more reduced (less direct release of untreated wastewaters and improvement of wastewater treatment). As a consequence it is important to quantify the significance of these discharges in order to estimate their impact on surface waters, as combined sewer overflows may rise due to rainfall increase with climate change. During two years (2010-2011), microbiological and physico-chemical parameters (conductivity, ammonium concentration and turbidity) have been measured in water samples from sewer outlets and in the Seine River (downstream Paris, France) during wet weather and after combined sewer overflows. The microbiological water quality was evaluated by the enumeration of two faecal indicator bacteria (FIB): (EC) and intestinal enterococci (IE).Escherichia coli Data analysis during dry periods showed a strong interdaily variability of the FIB concentrations, but no clear diurnal cycle. High variability was also observed during wet weather. Indeed FIB concentrations can be explained by a dilution model of domestic effluents by urban runoff water, the later being less concentrated in FIB and ammonium and having a low conductivity. This model suggests that a continuous monitoring of conductivity at network key points, especially at discharge points, could enhance our understanding of FIB release to surface waters. Weak correlation between FIB densities and turbidity suggests that turbidity does not constitute a suitable proxy to monitor microbial quality. However, considering the expected high levels of sedimentation in the Seine River, a particular attention should be given to the settleable fraction of FIB (attached to suspended matter). In general, IE were little more attached to settleable particles than EC in raw and surface water. During wet weather, this phenomenon tended to accentuate. The percent of settleable FIB was more important in the Seine River water than in wastewater, although suspended maters were lower. Unexpectedly, the two FIB had nearly the same behaviour in the Seine river after a discharge. These data were collected in order to model the FIB dynamics in the Seine River during wet weather situations. Measurements of FIB concentrations in combined sewer overflows are required as input data for such a modelling exercise.

380 THURSDAY 12 SEPTEMBER 2013, 17:30 PS-S1. Ecology of waterborne pathogens in the light of climate change

PS-S1.20. A CONCEPTUAL MULTI-ETIOLOGY MODEL FOR DISEASES INVOLVED IN MASS MORTALITY EVENTS OF THE PURPLE GORGONIAN PARAMURICEA CLAVATA IN THE MEDITERRANEAN SEA

Luigi Vezzulli, University of Genoa (Italy) Coauthors: Pezzati E, Huete-Stauffer C, Pruzzo C, Cerrano C, Ilan M

Mass mortality events of benthic invertebrates in the Mediterranean Sea are becoming an increasing concern with catastrophic effects on the coastal marine environment. Sea surface temperature anomalies linked to climate change are considered among the main causal factors triggering such events. We provided evidence that mortality episodes of Paramuricea clavata, one of the most affected coral species, were concomitant to a condition of prolonged high sea surface temperatures (≥ 20°C), low chlorophyll concentrations (≤ 1µg/L) and the presence of culturable Vibrio spp. in seawater. In particular, we identified a thermodependant TAV24 strain, belonging to the species Vibrio coralliilyticus, which satisfied Koch postulates and plays a significant role in triggering mass mortality of seafan corals in the Mediterranean Sea. Using massive parallel 16SrDNA gene pyrosequencing we also showed that the bacterial community associated to healthy P. clavata in pristine location was dominated by a single genus Endozoicomonas within the order Oceanospirillales which represented ~90% of the overall bacterial community. Interestingly P. clavata samples collected in human impacted areas and during disease events had higher bacterial diversity and abundance of disease-related bacteria, such as vibrios, than samples collected in pristine locations whilst showed a reduced dominance of Endozoicomonas spp.. Overall our data support the hypothesis for a multi-aetiology model of P. clavata disease where environmental stressful events, anthropogenic impact and microbial infections may cooperate to compromise coral immunity and trigger mortality outbreaks.

381 THURSDAY 12 SEPTEMBER 2013, 17:30 PS-S1. Ecology of waterborne pathogens in the light of climate change

PS-S1.21. ADHESION TO HUMAN INTESTINAL EPITHELIAL CELLS OF CRYPTIC ESCHERICHIA ISOLATES FROM MARINE SEDIMENTS

Carla Vignaroli, Department of Life and Environmental Science - DISVA, Polytechnic University of Marche (Italy) Coauthors: Magi G, Luna GM, Pasquaroli S, Di Cesare A, Biavasco F

Escherichia coli is considered as a gastrointestinal commensal of human and other warm-blooded animals and is commonly used as a fecal indicator to assess water quality. Recent reports on E. coli strains, isolated from aquatic ecosystems, have shown that a large number of environmental strains are included in five cryptic lineages, Escherichia clades I - V. However, scant data are available on the virulence and pathogenic properties of these lineages. This study analyzes 138 E. coli strains from coastal marine sediments collected in Marche, a central Italian region, for their belonging to the cryptic clades and ability to adhere to and invade human intestinal epithelial cells (Caco-2; Int407). The presence of genetic elements important for gut colonization, which are rarely found in environmental Escherichia isolates, and of selected virulence genes was also evaluated. Virulent cryptic isolates were subjected to MLST typing. Twenty of the 138 E. coli isolates belonged to cryptic clades III (1), IV (1) and V (18), and 90% of them (18/20) were positive on PCR analysis for the pduC gene (for diol utilization), typical of environmental strains. PCR assays showed that all 20 isolates were positive for genes malF, malP and glgA, involved in maltose and glycogen utilization; the complete fuc operon (fucP, fucK, fucU and fucR genes) for fucose utilization was carried by 12 (60%) strains, 11 of which belonged to clade V. Moreover 12/20 isolates were positive on PCR testing for the EAST1 toxin of enteroaggregative E. coli. In four strains (3 of clade V and 1 of clade III) adhesion to Caco-2 cells (expressed as percentage of initial inoculum) ranged from 1.2% to 5%, denoting a good ability to adhere compared with the negative (E. coli strains K-12, C600) and positive (E. coli O157:H7, ATCC35150) controls (<1% and 10%, respectively). Similar adhesion rates were obtained using Int407 cells, whereas internalization in Caco-2 or Int407 cells was observed neither in tested nor in control strains. Among adhesive strains a new Sequence Type (ST3613) and an ST described in avian isolates (ST2371), both carrying EAST1 and pduC genes, were identified by MLST and assigned respectively to clade V (E. coli PE9i15) and clade III (E. coli FE5e7). These findings suggest that detection of cryptic Escherichia isolates, carrying genetic traits typical of intestinal strains and virulence genes, in recreational waters may pose an insufficiently recognized public health risk.

382 THURSDAY 12 SEPTEMBER 2013, 17:30 PS-S1. Ecology of waterborne pathogens in the light of climate change

PS-S1.22. DETECTION METHODS TO STUDY NON-TUBERCULOUS MYCOBACTERIA IN AQUATIC SYSTEMS FACING GLOBAL CHANGE PRESSURE

Francoise S Lucas, LEESU, Université Paris Est Créteil (France) Coauthors: Radomski N, Roguet A, Cambau E, Moilleron R, Behr MA, Moulin L

Monitoring waterborne bacteria (including pathogens) in aquatic environments require taking in account a number of considerations regarding the targeted microbes, their detection level, and the analytical methods. These questions are particularly important for the quantification of “emerging” pathogens such as the non-tuberculous mycobacteria (NTM). NTM cover lot of different species including some opportunistic pathogens. The NTM detection methods that are available have usually been developed for clinical samples, and as consequence are not always adapted for the detection and quantification in aquatic environments. Culture methods are time- consuming and difficult due to the slow growth of NTM compared to other bacterial species commonly found in natural environments. We compared several disinfection procedures on river samples; however the results showed that in any cases the culture media are invaded by interfering bacterial and fungal species, which outcompete the slow growing NTM. Molecular methods constitute an interesting option; however, these techniques require being adapted in terms of specificity, sensitivity and detection limits. We developed two real time PCR methods, one based on 16S rRNA gene amplification, the other targeting the atpE gene. These two methods are highly specific toward the genus Mycobacterium, and have been successfully used to quantify genome of NTM in river, wastewater, rainwater and lake samples. These two methods allowed to evaluate NTM genome levels in raw wastewaters (5.5±3.9x105 copies/L) and to evaluate the impact of decantation on NTM removal. Decantation is a method that is largely employed for treating rainwater runoffs and as consequence it could protect the rivers against pathogen discharge. The spatial and temporal distribution of NTM in rivers has also been evaluated in contrasted climatic conditions, showing a probable dilution of NTM during storm events. The real time PCR methods we developed constitute useful tools in order to better understand NTM ecology and their response to climatic events such as the impact of increasing storm events in urban waters. It is obvious that the study of waterborne pathogens such as NTM require a set of methods that should be used in combination.

383

THURSDAY 12 SEPTEMBER 2013, 17:30 PS-S2. Protists: the ecological meaning of species specific morphologies

PS-S2.01. STUDY ON INTERRELATION BETWEEN OSTREOPSIS OVATA DINOFLAGELLATE AND ITS MICROBIOME

Andrea Curti, National Institute of Health (ISS), Rome (Italy) Coauthor: Angelici MC

Ostreopsis ovata, is a harmful Dinoflagellate producing palytoxin (PLTx) causing bloom all over the world included the Mediterranean Sea. This protist is a benthic species, but during his bloom is able to live as a planktonic species: free to move in the water column and therefore invade new sites. One of the most remarkable features of O. ovata is its ability to produce a mucous matrix where also bacteria live. Our goal is an understanding the relationships between this eukaryotic microbes and the prokaryotic ones living inside the mucus, especially regarding the protist trophism and toxin production. We cultivated a strain of O. ovata, isolated from the Naples bay kindly supplied by SZN. In order to understand which kind of relationship exist between O. ovata and bacteria living in its mucus, we performed both axenic and non-axenic culture of this protist. A PCR approach based on various conserved DNA region and specific coding sequences has been useful to identify, for the first time, different bacteria species inside the matrix of in vitro primary culture. We chose some selective criteria to research for bacteria species: to be biofilm producer, to have PLTx-like haemolysis behavior, and to be found associated to Palythoa sp, a Coelenterates species palytoxin producer. Axenic cultures allowed us to study different Ostreopsis behaviors regarding the degree of mucous production and the microbe growth rate when the protist lifestyle is strictly autotrophic. Moreover biochemical tests have been useful to feature the Ostreopsis mucus as a saccharidic matrix and morphological studies with SEM technology let us to see different bacteria distribution in the mucous matrix and on isolates cells of Ostreopsis. The benthic nature and the mucus production by this mixotrophic protist bring it in close contact with different bacteria species but the relationships between prokaryotic and eukaryotic cells are still completely unknown. It is still unknown if these relationships are definitively a symbiosis and if it contributes to the association morphology. The protist capability to switch from heterotrophic to autotrophic lifestyle stresses the high degree of adaptation of this species and does point out the necessity to better understand its advantage by co-habitation with prokaryotes and which kind of regulatory mechanisms are at the basis of its toxicity. Some preliminary results on the bacterial association with O. ovata and studies on the toxin production mechanism both in non-axenic and in axenic cultures are in progress.

384 THURSDAY 12 SEPTEMBER 2013, 17:30 PS-S2. Protists: the ecological meaning of species specific morphologies

PS-S2.02. ISOLATION AND CULTIVATION OF ANAEROBIC HETEROTROPHIC NANOFLAGELLATE FROM THE MEROMICTIC LAKE SUIGETSU, JAPAN

Ryuji Kondo, Fukui Prefectiral University (Japan) Okamura T

Heterotrophic nanoflagellates (HNF) are known to play a major role in consumption of bacteria and in the process of nutrient recycling in the aquatic microbial food web. However, little is known about the ecology of HNF in the microbial food web of . More recently, we have shown that HNF are present and act as bacterial consumers with high potential bacterivory in sulfidogenic, anoxic layer of the meromictic Lake Suigetsu, Japan. However, their physiology remains obscure. The aim of this study was isolation and cultivation of anaerobic HNF from anoxic layer of Lake Suigetsu for understanding the microbial food web ecology in anoxic aquatic environments. To obtain an initial enrichment c ulture, water samples were taken from anoxic layers of Lake Suigetsu and were added to anaerobic test tubes with butyl rubber stopper containing one wheat grain or yeast extract (final conc. 100 mg L-1) using a needle and syringe. Headspace of the tube was replaced with N2 and the tubes were incubated at 20°C in the dark. Oxic-anoxic condition was monitored by addition of resazurine (1 mg L-1) to the culture. After initial enrichment, anaerobic HNF cultures were maintained by serial transfer at monthly intervals to a modified medium for sulfate-reducing bacteria or a lake water-based medium. Successful enrichment cultures were obtained from the anoxic water layer of Lake Suigetsu. Microscopic observation revealed the presence of different morphological types of HNF in the enrichment cultures. An obligate anaerobic HNF strain was isolated by serial dilutions of the enrichment culture and a facultative anaerobic HNF strain was isolated by capillary isolation technique. These strains were grown in polyxenic culture with unidentified bacteria. Furthermore, we were able to enrich anaerobic HNF from the bottom sediment of the lake. These isolates and enrichment culture can be useful for understanding the ecology and physiology of anaerobic HNF in nature.

385 THURSDAY 12 SEPTEMBER 2013, 17:30 PS-S2. Protists: the ecological meaning of species specific morphologies

PS-S2.03. COMMUNITY STRUCTURING AND ACTIVITY IN ABUNDANT AND RARE MARINE MICROEUKARYOTES INVESTIGATED WITH ILLUMINA & 454 SEQUENCING

Ramiro Logares, Institute of Marine Sciences (ICM-CSIC), Barcelona (Spain) Romac S, de Vargas C, Massana R

Most biological communities are composed by a few abundant and many rare taxa, and in prokaryotes, the large amount of rare taxa is known as the “Rare Biosphere”. Despite the importance of microeukaryotes in marine communities, we still know very little on their species abundance distributions as well as on the patterns presented by abundant and rare taxa across communities. Here we focus in these questions using Illumina (GAIIx, 100 bp) sequencing of environmental rRNA (18S V9 region), which allowed a very deep taxonomic sampling of communities. Our samples originated from six marine-coastal locations in Europe (sites in Bulgaria, France, Italy, Norway and Spain) and encompassed surface samples from three size-fractions, the picoplankton (0.8-3.0 μm), nanoplankton (3.0-20.0 μm) and microplankton (20.0-2, 000 μm). About 15 Gigabases (i.e. 15x10 nucleotides) of amplicon sequence data were produced and Operational Taxonomic Units (OTUs) were defined at 95% similarity threshold. Our results indicated that we approached to richness saturation in the complete dataset. In all the studied communities, evenness was very low. Communities within each size fraction showed no fit to Hubbel’s neutral model, suggesting environmental effects in community structuring. The proportion of abundant and rare OTUs was relatively constant between samples, pointing to similar OTU-abundance distributions. Abundant communities were structured first by size fraction and then by site, while rare communities were mostly structured by site. The rare microeukaryote biosphere presented a characteristic phylogenetic identity; several rare taxa had no evolutionary relatives among the abundant, while most abundant taxa had relatives among the rare. Abundant taxa were phylogenetically more clustered than what it was expected by chance, suggesting environmental selection. The relative abundance of the OTUs (obtained with 454; 18S V4 region; 99% clustering) that were present in both the DNA and RNA datasets followed in average a 1:1 relationship, suggesting that dormancy or high-activity are not common in surface marine microeukaryotes. In summary, our data indicate that marine microeukaryote assemblages encompass an abundant community component with a limited number of OTUs as well as a rare biosphere with many OTUs; each component with specific characteristic and ecological roles.

386 THURSDAY 12 SEPTEMBER 2013, 17:30 PS-S2. Protists: the ecological meaning of species specific morphologies

PS-S2.04. Ecological properties of newly isolated anaerobic heterotrophic nanoflagellate strains

Takaiko Okamura, Graduate School of Bioscience and Biotechnology, Fukui Prefectural University, Obama (Japan) Kondo R

Heterotrophic nanoflagelllates (HNF) are important bacterial grazers in microbial food webs of aquatic environments. Recently we have demonstrated that HNF in sulfidogenic, anoxic layers of the meromictic Lake Suigetsu, Japan, actively consume bacterioplankton, indicating the presence of microbial food web in anoxic waters. However, little is known about their eco-physiological properties. The aim of present study was to investigate growth physiology and prey properties of anaerobic HNF to reveal the ecology of anaerobic HNF. We isolated two anaerobic heterotrophic flagellate strains from anoxic layer of the lake: (1) the strain LSccOV-1, obligate anaerobic, and oval cell with one long flagellum; (2) the strain LSccTR-1, facultative anaerobic, and tear-shaped cell with two flagella. 18S rDNA sequence analysis showed that LSccOV-1 and LSccTR-1 were phylogenetically related to Mastigamoeba simplex (Amebozoa, family Mastigamoebadie) and to Wobblia lunata (Stramenopile, class Placididea), respectively. Sequence similarities of those strains to any known species were less than 90%, suggesting that the isolates are novel species. Ingestion rates on bacteria by those strains were estimated using fluorescence labeled beads (FLBead). We could not estimate ingestion rate of LSccOV-1 because FLBead were trapped by extracellular matrix of flagellate cell surface. Ingestion rates of LSccTR-1 under anoxic condition were higher than those of oxic condition. Specific growth rate of the strain under anoxic condition was lower (0.9 day-1) than that under oxic condition (2.3 day-1), and its growth efficiency (growth/ingestion) under anoxic condition was estimated to be about 15% of that of oxic condition. Thus, anaerobic growth of the strain LSccTR-1 is less efficient relative to aerobic growth. Our recent study showed that the biomass ratios of HNF/bacteria in the anoxic layer were lower than those in the oxic layer of Lake Suigetsu. Low efficiency of anaerobic HNF growth may cause low HNF/bacteria ratio in anoxic layer of the lake.

387 PATRONAGES, SPONSORS AND SUPPORTERS

388 AUTHOR INDEX Axelsson-Olsson D ...... 109 Bertoni R ...... 37; 175; 215; 217 Abad N ...... 209 Ayo B ...... 200; 209; 234 Bertos-Fortis M ...... 216 Abella J ...... 164 Azam F ...... 21 Bertuzzo E ...... 78; 302 Acinas SG ...... 80; 82; 296 Azúa I ...... 200 Besemer K ...... 95; 302 Ackermann M ...... 96 Bestetti G ...... 31 Acquaviva MI ...... 203 Bäckman S ...... 75 Bettarel Y ...... 142; 339; 353 Acuna V ...... 118 Bae HS ...... 189 Bhardwaj V ...... 255 Ade P ...... 363 Bakenhus I ...... 69 Bianchi F ...... 151 Adeboyejo F ...... 59 Baker-Austin C ...... 364; 374 Biavasco F ...... 368; 381 Ademollo N ...... 152 Balagué V ...... 176 Biderre-Petit C ...... 275 Aebischer T ...... 161 Baldrian P ...... 334 Biegala I ...... 160 Agawin NS ...... 156 Bale N ...... 210 Bienhold C ...... 117 Agis M ...... 276; 339 Balestra C ...... 155 Billerbeck S ...... 303 Agogué H ...... 131; 283 Balseiro E ...... 41; 217 BinHumoudi KM ...... 332 Ahmed O ...... 322 Baltar F ...... 38; 42; 81; 295; 314 Birgel D ...... 54 Aigle A ...... 157 Bana Z ...... 200; 209; 234 Birtel J ...... 304 Akfur C ...... 75 Baneras L ...... 116 Bizic-Ionescu M ...... 274 Akob D ...... 62 Barani A ...... 256 Blache Y ...... 256 Akram N ...... 38; 81 Barantal S ...... 163 Blain S ...... 281 Alcon E ...... 156 Barbato M ...... 182; 323 Blanchet M ...... 276 Alifano P ...... 205; 206; 300 Barberán A ...... 83 Blancheton JP ...... 193 Alkhajeh AS ...... 123 Barcina I ...... 114; 172 Blokesch M ...... 78 Allgaier M ...... 105; 280 Barisić J ...... 321 Bochdansky A ...... 235 Almeida A ...... 140; 318; 357; 358 Bartolomé M ...... 164 Bodelier PLE ...... 70 Alneberg J ...... 292 Bass D ...... 48 Boenigk J ...... 48 Alonso C ...... 44 Bastidas Navarro M ...... 41 Böer SI ...... 365; 366 Alonso-Sáez L ...... 115 Batani G ...... 88 Boero F ...... 204; 300 Amalfitano S ...... 37; 88; 152; 193; 326 Battin T ...... 47; 95; 278; 302 Boetius A ...... 117; 129 Amann R ...... 270; 274 Baudoux AC ...... 353 Boeuf D ...... 233 Amblard C ...... 230 Bavestrello M ...... 271 Bohannan B ...... 83 Ambrosini R ...... 31 Beardall J ...... 232 Boisset C ...... 77 Amin S ...... 238 Beardsley C ...... 69 Bolch CJS ...... 223 Amin SA ...... 282 Beaugeard L ...... 131 Boldarjeva K ...... 178 Andersen GL ...... 207 Becking L ...... 308 Bolhuis H ...... 305 Andersen T ...... 194 Bees MA ...... 65 Bongiorni L ...... 33 Andersson A ...... 113; 125; 292; 371 Behounek B ...... 278 Bonin P ...... 157; 164 Andersson AC ...... 75 Behr MA ...... 382 Bonnemoy F ...... 136 Andersson AF ...... 293; 314 Behrendt L ...... 254 Borchard C ...... 141 Andersson S ...... 85 Beier S ...... 84; 281 Bordalo A ...... 287 Andrade da Costa V ...... 124 Béjà O ...... 344; 355 Borges AV ...... 39 Angelici MC ...... 363; 383 Belkin N ...... 298 Borin S ...... 182; 323 Antajan E ...... 77 Bellamy J ...... 89 Borrego C ...... 29; 39; 118; 170; 171 Antequera C ...... 200 Bengtsson M ...... 47 Borrull E ...... 80; 200 Antón J ...... 144 Ben-Hamo Hilla ...... 273 Boschker E ...... 214 Antonioli M ...... 33; 252; 301 Benke Imre P ...... 212 Boschker HTS ...... 336 Arana I ...... 114; 172 Benkendorff K ...... 267 Bosma T ...... 70 Arandia-Gorostidi N ...... 115; 128 Bentzon-Tilia M ...... 168 Böttjer D ...... 346 Ardelan M ...... 225 Berdjeb L ...... 213 Boucher D ...... 275 Armbrust V ...... 238 Berg C ...... 107 Bouchez A ...... 256 Arnosti C ...... 294 Bergauer K ...... 173 Boudahmane L ...... 376 Arora DK ...... 146 Bergen B ...... 158 Bouillon S ...... 39 Arrieta JM ...... 49; 80; 98; 209 Bergfeld T ...... 159 Bourne DG ...... 66; 361 Asmani K ...... 253 Berman T ...... 53 Bouvier C ...... 339; 353 Astor Y ...... 28 Berman-Frank I ...... 53; 298 Bouvier T ...... 339; 353 Atamna-Ismaeel N ...... 369 Bernardy E ...... 369 Bouvy M ...... 276; 353 Attermeyer K ...... 280 Bernd W ...... 303 Bouyssiere B ...... 164 Audic S ...... 296 Bertilsson S56; 58; 85; 201; 247; 309; 322Bowman J ...... 239 Autio R ...... 25 Bertolini V ...... 31 Branca MR ...... 295

389 Bratbak G ...... 327; 340 Céa B ...... 120 Danovaro R ...... 33; 57; 277; 342; 356 Brauer V ...... 36 Cecere E ...... 203 Danza F ...... 236 Brazel D ...... 294 Celussi M ...... 121 Darchambeau F ...... 39 Brennholt N ...... 365; 366 Cernadas M ...... 28 de Beer D ...... 59 Bressy C ...... 256 Cerrano C ...... 380 De Bruijn I ...... 292 Brettar I ...... 76; 370; 373 Chain P ...... 294 De Corte D ...... 97; 257 Briand JF ...... 256 Chanton J ...... 189 De Domenico E ...... 162; 241 Brinkhoff T ...... 69 Chardon C ...... 213 De Meester L ...... 202 Bronner G ...... 283 Chariton A ...... 137 de Rezende JR ...... 90 Brown MH ...... 184; 299 Charriere B ...... 120 De Sanctis M ...... 167 Bruneel O ...... 310 Chifflard P ...... 302 de Vargas C ...... 296; 385 Brussaard C ...... 135; 141 Chirurgien L ...... 120 de Voogd N ...... 186 Buchan A ...... 291 Chistoserdov A ...... 28 Debeljak P ...... 243 Buchholz I ...... 268 Chronakova A ...... 334 Debroas D ...... 275; 283; 353 Buckley H ...... 89 Cicuta P ...... 264 Dedysh S ...... 348 Buergmann H ...... 61; 119; 161 Cisternas B ...... 225 deFerra F ...... 323 Bunn S ...... 286 Cleary D ...... 186; 308 Degerman R ...... 113 Burns N ...... 47 Coci M ...... 217; 279; 324 del Giorgio P ...... 34; 183; 199; 240 Burrell TJ ...... 134; 306 Collin H ...... 160 Del Negro P ...... 121 Busquets A ...... 156 Collins S ...... 22; 228 Delesmont R ...... 77 Bussmann I ...... 330 Colombet J ...... 354 Dell'Anno A ...... 277; 342; 356 Butturini A ...... 88; 326 Combe M ...... 339 Dellisanti W ...... 121 Comte J ...... 34 Delpin M ...... 93 Cabral A ...... 71 Conan P ...... 346 Denaro R ...... 165 Caburlotto G ...... 151 Confurius V ...... 336 Denonfoux J ...... 275 Cagatay TI ...... 367 Conte A ...... 162; 191 Descals E ...... 149 Cagnon C ...... 163; 164 Contesini M ...... 215 Descy JP ...... 39 Calado R ...... 357 Cooper MB ...... 65; 122 Desnues C ...... 353 Calkiewicz J ...... 231 Corinaldesi C ...... 277; 342; 356 Devlin S ...... 43 Callieri C ... 37; 175; 215; 217; 279; 350 Cornejo-Castillo FM ...... 80 Devlin Shawn P ...... 237 Calvo E ...... 42; 81 Corno G ...... 37; 217; 279; 324 Di Cesare A ...... 368; 381 Camacho A ...... 29; 106; 132; 191 Corral P ...... 181 Di Pippo F ...... 167 Cambau E ...... 382 Costa L ...... 357; 358 Di Tullio G ...... 219 Campanile F ...... 324 Cottrell MT ...... 233 Dias JM ...... 318 Canesi L ...... 271 Coz-Rakovac R ...... 321 Díaz-Pérez L ...... 128 Canfield D ...... 39 Cram JA ...... 176 Dibidetto M ...... 317 Caparros J ...... 276 Cravo-Laureau C ...... 163; 164 Dieckmann G ...... 25 Cappello S ...... 317; 333 Creer S ...... 231 Díez B ...... 181 Caprioli R ...... 204 Crisafi F ...... 165 Diez-Vives C ...... 80 Carbon A ...... 164 Crowe SA ...... 39 Diolaiuti G ...... 31 Cardon Z ...... 289 Croze O ...... 65; 122 Dirren S ...... 55; 111 Carpani G ...... 323 Crump B ...... 73 Dittmar T ...... 27; 45; 59; 92; 196; 285 Carrano CJ ...... 282 Cryer C ...... 156 Djurhuus A ...... 307 Caruso G ...... 205 Cuesta I ...... 171 Doan NH ...... 353 Casagrandi R ...... 78 Cuevas LA ...... 218; 222; 225 Doherty M ...... 73 Casamayor EO ...... 83 Cui Y ...... 166; 211 Domaizon I ...... 283 Case B ...... 89 Cunha A ...... 140; 318; 357; 358 Donis D ...... 129 Casella P ...... 152; 193 Cuny P ...... 163; 164 Dorado-Garcia I ...... 237 Casiot C ...... 310 Cuperová Z ...... 178 Doubell MJ ...... 108 Casotti R ...... 155 Curti A ...... 383 Douglas M ...... 286 Casper P ...... 280 Cypionka H ...... 349 Drewes F ...... 343 Castellani M ...... 250 Cyronak T ...... 219 Duarte CM ...... 49; 80; 98 Castenholz RW ...... 272 Duarte L ...... 186 Castro L ...... 222 D’Agata C ...... 31 Dubilier N ...... 63 Catala P ...... 276 Dachs J ...... 49 Dubosq K ...... 164 Catalfamo M ...... 165; 333 Daffonchio D ...... 79; 182; 323 Duffaud E ...... 230 Catania V ...... 317; 333 Daneri G ...... 222 Dugat-Bony E ...... 275 Cavallo RA ...... 203 Daniel R ...... 69 Duran R ...... 163; 164; 310 Cavicchioli R ...... 82 Dann L ...... 93; 341 Durham B ...... 238

390 Duty O ...... 366 Freese HM ...... 345 Goldstein RE ...... 65; 122 Dyksma S ...... 32 Freimann R ...... 119 Golebiewski M ...... 231 Freitas R ...... 308 Gomariz M ...... 144 Eckert E ...... 64 Freixa A ...... 26; 88; 326 Gomes A ...... 80 Eiler A ...... 58; 74; 85; 201; 309 Frindte K ...... 280 Gomes N 140; 186; 284; 308; 357; 358 Ejarque E ...... 88; 326 Fuchs A ...... 280 Gomez P ...... 225 ElAhwany A ...... 259 Fuchs BM ...... 270; 274 Gomez-Pereira P ...... 40 El-Bessoumy AA ...... 258 Fuhrman JA ...... 176 Goncalves A ...... 379 EL-Sersy N ...... 258 Fukuda H ...... 263 Goni-Urriza MS ...... 164 ElSharif H ...... 259 Fukui M ...... 179 Gonzàlez H ...... 218; 222 El-Sharouny EE ...... 258 Funari E ...... 229; 363 González HE ...... 225 El-Tarabily K ...... 123; 325 Furuya K ...... 320 González JM ...... 38; 82 Emerson D ...... 72 González MJ ...... 81 Emmerich B ...... 36 Galand PE ...... 30; 101; 283 Gonzalez-Aviles GD ...... 364 Enav H ...... 344 Galgani L ...... 148 Got P ...... 142 Encarnacao P ...... 338 Galipeau P ...... 183 Götz F ...... 349 Endres S ...... 148 Gálvez Zenteno MJ ...... 281 Goutx M ...... 346 Engel A ...... 141; 148 Gandolfi I ...... 31 Granberg M ...... 75 Erga SR ...... 359 Garaizabal I ...... 114; 172 Grande C ...... 271 Erichsen ES ...... 327 Garcia C ...... 240 Grant J ...... 110 Eronen-Rasimus E ...... 25 García FC ...... 80 Grant MAA ...... 264 Espinoza M ...... 225 Garcia JA ...... 54; 86; 173; 257 Grattepanche JD ...... 110 Eugster B ...... 111 Garcia M ...... 85 Gravili C ...... 300 Garcia N ...... 120 Graziano M ...... 241 Fagervold S ...... 30 Garcia SL ...... 50 Green D ...... 223; 261 Fahy A ...... 310 García-Armisen T ...... 39 Green DH ...... 282 Farnelid H ...... 168 Garcia-Lledó A ...... 116 Gregoracci G ...... 71 Fasching C ...... 95; 278 García-Zarandona I ...... 200 Gregori G ...... 120; 256 Faust K ...... 296 Gärdes A ...... 248; 282 Griessler T ...... 351 Faydaci B ...... 336 Garneau ME ...... 126 Grob C ...... 40 Fazi S ...... 88; 270; 326 Garnier C ...... 256 Gröbe L ...... 268 Feng S ...... 239 Garren M ...... 66 Grossart HP50; 105; 143; 196; 274; 280; 335 Fernandes Cardoso de Oliveira AJ124; 169Gasol JM 42; 80; 81; 170; 176; 198; 208; 234Grosse J ...... 214 Fernàndez-Guerra A ...... 83 Gassie C ...... 163; 164 Grujcić V ...... 242 Fernandez-Vidal L ...... 85 Gatto M ...... 78 Guarch Ribot A ...... 88; 326 Ferreira K ...... 164 Gaubert M ...... 121 Guasco S ...... 157; 164 Ferrera I ...... 170; 208 Gazeau F ...... 121 Gudaz C ...... 322 Ferrier-Pages C ...... 353 Genovese L ...... 165; 317 Guerrini F ...... 127 Ferriol P ...... 156 Genovese M ...... 165 Gugliandolo C ...... 132 Field E ...... 72 Gerdts G ...... 100; 315; 319 Guidi F ...... 127 Figueroa DA ...... 113; 125 Ghiglione JF ... 101; 120; 174; 260; 346 Guigue C ...... 346 Fillinger L ...... 305 Ghozlan H ...... 259 Fillol M ...... 171 Giangrande A ...... 205 Haeusler S ...... 59 Findlay S ...... 119 Giannakourou A ...... 121 Hagemann M ...... 298 Fitch AJ ...... 299 Giardina M ...... 324 Hahn M ...... 48; 106; 329 Fleer V ...... 316 Gibb K ...... 137 Hallam SJ ...... 82 Flórez-Márquez AE ...... 350 Giblin A ...... 289 Haller L ...... 188 Fonda Umani S ...... 252; 301 Gich F ...... 171 Halpern M ...... 369; 370 Fontaneto D ...... 279 Giebel HA ...... 69; 221; 303 Hamasaki K ..... 166; 211; 224; 263; 320 Forn I ...... 80 Giesecke R ...... 222 Hammer BK ...... 369 Forsman M ...... 371 Gilbert F ...... 163; 164 Hansen LH ...... 254 Förstner KU ...... 105 Giovannoni SJ ...... 82 Hansman RL ...... 243 Foster R ...... 52 Giske J ...... 250 Hanson C ...... 90 Fourquez M ...... 281 Giuliano L ...... 165 Hanson NW ...... 82 Frade P ...... 54 Glaeser J ...... 105 Hao DM ...... 130 Frank AH ...... 86 Glaeser SP ...... 105 Harder J ...... 168 Franzetti A ...... 31 Glaring M ...... 272 Hart M ...... 261 Franzo A ...... 121 Glava N ...... 150 Hartenell R ...... 374 Fraschetti S ...... 206 Glöckner FO ...... 83 Hartmann M ...... 40

391 Hashihama F ...... 320 Janssen F ...... 366 Koike I ...... 224 Hatton A ...... 261 Jardine T ...... 286 Kojima H ...... 179 Hauk G ...... 366 Javerliat F ...... 310 Koll U ...... 106 Hauruseu D ...... 244 Jeanthon C ...... 233 Köllner K ...... 61 Heinemeyer EA ...... 366 Jeffrey W ...... 260 Kondo R ...... 384; 386 Heinrich F ...... 309 Jeffries TC ...... 67; 138; 299 Konstantinopoulou A ...... 121 Heldal M ...... 327; 340 Jessen GL ...... 129 Kopf M ...... 298 Herberg E ...... 47 Jezbera J ...... 48; 106; 178; 311 Kos Kramar M ...... 204; 265 Herlemann D ...... 27; 158; 196 Jezberova J ...... 106; 311 Köstner N ...... 103; 351 Hernández M ...... 208 Jezequel R ...... 163; 164 Kottmann R, ...... 83 Hernández S ...... 175 Jimenez MA ...... 98 Kovac N ...... 150 Hernando V ...... 80 Jobard M ...... 230 Krishnappa M ...... 149 Hernando-Morales V ...... 176; 208 Jones JL ...... 364 Kruspe CP ...... 103 Herndl GJ54; 86; 97; 103; 173; 246; 257; 351Jones ML ...... 316 Kuesel K ...... 62 Herrig I ...... 365 Jones RI ...... 43; 58; 237 Kühl M ...... 254; 272 Herrmann M ...... 62 Jorgensen BB ...... 90 Kulichevskaya I ...... 348 Hervio-Heath D ...... 77 Jost G ...... 349 Kuo K ...... 179 Hess W ...... 298 Jost S ...... 48 Kuosa H ...... 25 Heyber S ...... 268 Joubori BA ...... 332 Kushmaro A ...... 273 Hicks RE ...... 192 Jouquet P ...... 142 Kuypers M ...... 96 Hidalgo S ...... 336 Joux F ...... 260; 276 Kwon M ...... 372 Höfle M ...... 76; 370; 373 Jung TS ...... 262 Holmes ME ...... 189 Jung YT ...... 153 Laas P ...... 312 Holohan BA ...... 192 Jung-Hoon Y ...... 153; 154 Labonté J ...... 104 Honda M ...... 263 Jürgens K . 27; 107; 148; 158; 196; 349 Labrenz M ...... 349 Hopmans EC ...... 210 Lacerot G ...... 44 Hornak K ...... 48; 328 Kaartokallio H ...... 25 Lami R ...... 233 Hötzinger M ...... 329 Kaftan D ...... 227 Landry ZC ...... 82 How D ...... 93 Kalander MJ ...... 332 Langenheder S ...... 99 Hu Y ...... 293 Kalyan CM ...... 207 Laoudi S ...... 310 Hubert C ...... 90 Kameyama S ...... 166 Lapierre JF ...... 199 Huete-Stauffer C ...... 380 Kandol G ...... 24 Lara E ...... 80 Huete-Stauffer TM ...... 115; 128 Kaneko R ...... 211; 263; 320 Larkum AWD ...... 254 Hugerth L ...... 293; 314 Kang CH ...... 154 Larsen JEN ...... 272 Hugoni M ...... 283 Karhunen J ...... 43 Larsen O ...... 188 Huisman J ...... 36 Karsenti E ...... 296 Larsen P ...... 172 Hulston DA ...... 134 Kasalický V ...... 48; 178; 242; 311 Latour D ...... 136; 230 Hüpeden J ...... 177 Kato K ...... 60; 130 Lau K ...... 313 Hupfer M ...... 280 Kato Y ...... 269 Lauga B ...... 310 Katsuyama C ...... 60 Lauro FM ...... 82 Ijichi M ...... 166 Katz LA ...... 110 Lavazza D ...... 323 Ilan M ...... 380 Kazamia E ...... 264 Lavergne C ...... 131 Iniguez V ...... 310 Kazazić S ...... 321 Lavik G ...... 96 Inostroza I ...... 225 Kendrick J ...... 219 Law CS ...... 134; 306 Interdonato F ...... 193 Khanal K ...... 207 Lawrence D ...... 228 Intertaglia L ...... 276 Kiene R ...... 287 Le Berre B ...... 256 Ionescu D ...... 59; 274 Kiene RP ...... 291 Le Grand J ...... 253 Iriarte JL ...... 218; 222; 225 Kim SJ ...... 372 Le Moal M ...... 160 Iriberri J ...... 209; 234 Kinoshita T ...... 60 Lear G ...... 89 Islam MS ...... 78 Kirchman DL ...... 101; 233 Lee H ...... 372 Israelsson S ...... 109 Kisand V ...... 312 Lee P ...... 219 Ito M ...... 179 Kjelleberg S ...... 94; 207 Lefèvre D ...... 120 Iwata T ...... 187 Klenk HP ...... 288 Legrand B ...... 136 Klimiuk A ...... 351 Legrand C ...... 216; 314 Jacquet S ...... 213; 347; 362 Klobucar G ...... 321 Lehtiö J ...... 295 Jadan M ...... 321 Kobayashi Y ...... 179 Lekunberri I ...... 257 Jahn D ...... 268 Koblizek M ...... 178; 227; 244; 290 Lemmens P ...... 202 Jakubowska N ...... 226 Kodama T ...... 320 Lennon J ...... 91 Janeau JL ...... 142 Kogure K ...... 224; 331 Lentini V ...... 132

392 Lepleux C ...... 180 Mandel-Gutfreund Y ...... 344 Modenutti B ...... 41; 217 LePoupon C ...... 256 Manecki M ...... 27; 196 Moilleron R ...... 382 Lesage L ...... 379 Manfrin C ...... 33 Molari M ...... 190 Leskinen P ...... 360 Manganelli M ...... 229 Molina V ...... 281 Lesnik R ...... 76 Manini E ...... 190 Monaghan M ...... 280 Leunert F ...... 105 Mantha P ...... 207 Moné A ...... 283 Lewis G ...... 313 Mapelli F ...... 182; 323 Monteil S ...... 353 Lezzi M ...... 300 Maranger R ...... 183 Monteiro M ...... 284 Liang Y ...... 207 Marcial Gomes NC ...... 318 Montiel-Hernández JR ...... 350 Lichtschlag A ...... 129 Mari L ...... 78 Moon K ...... 372 Lieten S ...... 70 Marks RS ...... 273 Moran MA ...... 68; 73; 82; 84; 238 Lima-Mendez G ...... 296 Marrasé C ...... 42; 81; 234 Morán XAG ...... 80; 115; 128; 208 Lin CHM ...... 179 Martin A ...... 40 Morana C ...... 39 Lindh M ...... 314 Martinez-Garcia M ...... 82; 294 Morenkov O ...... 92 Lindroos A ...... 360 Martinez-García M ...... 144 Mothana AA ...... 258 Lindström E ...... 309 Martinez-Urtaza J ...... 364 Mouchel JM ...... 379 Lips I ...... 312 Martin-Platero A ...... 181 Moulin L ...... 376; 382 Lipsewers Y ...... 210 Martiny J ...... 90 Moyà G ...... 156 Listmann L ...... 107 Martiny JBH ...... 87 Moya L ...... 45; 285 Littmann S ...... 96 Marx C ...... 102 Muck S ...... 103; 351 Lleo MM ...... 151 Mary I ...... 283 Müller A ...... 90 Llirós M ...... 39 Masin M ...... 227 Münch K ...... 268 Lo Giudice A ... 132; 162; 191; 193; 241 Mass E ...... 101 Münch R ...... 268 Logares R ...... 198; 309 Massana R ...... 80; 385 Munk P ...... 87 Logue J ...... 309 Massé S ...... 183 Murakami A ...... 187 Lokmer A ...... 74; 133 Mathisen P ...... 371 Murat A ...... 222 Loman N ...... 292 Matousu A ...... 242; 330 Murray AE ...... 101 Long RA ...... 127 Matsuura T ...... 269 Mushi D ...... 373 Lorages R ...... 385 Matthews B ...... 161; 304 Mussmann M ...... 32 Losic D ...... 108 Maugendre L ...... 121 Muthusamy S ...... 295 Lovejoy C ...... 101 Maugeri T ...... 132 Myklestad SM ...... 225 Loy A ...... 90 Mayol E ...... 98 Lucas FS ...... 376; 379; 382 Mazur-Marzec H ...... 216 Nagaosa K ...... 60; 130 Lucas J ...... 315 Mazzola S ...... 317 Nagata T ...... 23; 246; 263 Luden K ...... 366 McDougald D ...... 188 Nakajima Y ...... 331 Luna GM ...... 375; 381 McMahon KD ...... 50; 85 Nakano SI ...... 187 Lundin D ...... 81; 295; 314 McManus GB ...... 110 Napieralska A ...... 226 Lundmark E ...... 75 Medina-Sánchez JM ...... 237 Narracci M ...... 203 Luo H ...... 82 Medova H ...... 227 Nascimento J ...... 71 Lyman A ...... 72 Meerhoff M ...... 44 Näslund J ...... 75 Lyra C ...... 25 Mege M ...... 275 Navarro J ...... 225 Meisterl K ...... 249 Neale M ...... 313 Maas EW ...... 134; 306 Menolascina F ...... 66 Nedoma J ...... 48; 311 Maat D ...... 135 Merlino G ...... 323 Needham DM ...... 176 Mabrouk M ...... 266 Merroune A ...... 142 Nelson T ...... 286 Macek M ...... 217; 350 Messer L ...... 184 Nelson TN ...... 137 Machado A ...... 291 Messina E ...... 317 Nesati V ...... 94 Mackenzie R ...... 181 Metsis M ...... 312 Neuenschwander S ...... 352 Magagnini M ...... 182 Meysman FJR ...... 336 Neumann A ...... 268 Magalhaes C ...... 284; 287 Michaud L ...... 132; 162; 191; 193; 241 Newton AE ...... 364 Magalhães C ...... 291 Michotey V ...... 157; 164 Newton K ...... 93; 138; 299; 341 Magi G ...... 381 Mihalcea C ...... 31 Ng C ...... 188 Maguire I ...... 321 Milici M ...... 297 Ngugi D ...... 185 Mahaffey C ...... 184 Militon C ...... 157; 163; 164 Nguyen KH ...... 353 Mahmud ZH ...... 78 Mishra S ...... 212 Nguyen NL ...... 353 Malkin SY ...... 336 Misson B ...... 136; 230 Nguyen TT ...... 353 Mallet C ...... 136 Mitchell J ...... 108; 341 Nicolas JL ...... 253 Malmstrom R ...... 85 Mitchell JG ...... 93; 138; 232; 299; 361 Nielsen P ...... 172 Mancini G ...... 333 Miyake S ...... 185 Nieto JM ...... 310

393 Niggemann J ...... 92 Pereira R ...... 373 Raimbault P ...... 120 Nilsson E ...... 314 Perez MT ...... 197; 245 Raina JB ...... 66 Nino JP ...... 199 Pernice M ...... 80 Raingeard D ...... 188 Noguerola I ...... 29 Pernthaler J46; 51; 55; 64; 92; 126; 328; 337;Rajal V 352 ...... 94; 207 Noriega B ...... 59 Perujo N ...... 26 Raju GH ...... 149 Norland S ...... 340 Pescheck F ...... 139 Ralph P ...... 67 Nunoura T ...... 251; 356 Peter H ...... 45; 74; 285 Ramette A ...... 129 Nyi Nyi N ...... 207 Petrocelli A ...... 203 Ramió-Pujol S ...... 116 Petrou K ...... 67 Ramos-Esplá AA ...... 144 Obernosterer I ...... 30; 84; 281 Petton B ...... 253 Rappazzo AC ...... 193 Offre P ...... 173 Peura S ...... 58; 201 Rasconi S ...... 194 Ogata H ...... 296 Peyret P ...... 275 Rastelli E ...... 356 Ogawa H ...... 263 Peyretaillade E ...... 275 Ravasi D ...... 195 Ogden S ...... 267 Pezzati E ...... 271; 380 Rayner T ...... 286 Ogram A ...... 189 Pezzolesi L ...... 127 Reche I ...... 80 Okamura T ...... 384; 386 Pfreundt U ...... 298 Réhel K ...... 256 Okuda N ...... 179; 187 Philosof A ...... 355 Reinthaler T ...... 86; 246 Olam ZA ...... 258 Picazo A ...... 29 Reuben S ...... 207 Omori Y ...... 166 Piceno Y ...... 207 Reynaud S ...... 353 Opitz S ...... 62 Pieper D ...... 297 Ricao Canelhas M ...... 247 Oriol L ...... 276 Pierce M ...... 192 Richter M ...... 32 Orlic S ...... 274 Piiparinen J ...... 139 Riebesell U ...... 141 Orruno M ...... 114; 172 Pinhassi J ..... 38; 42; 81; 109; 295; 314 Rieck A ...... 196 Ortega-Retuerta E ...... 260; 276 Pinto A ...... 140 Riemann L ...... 87; 168 Ostrowski M ...... 40 Pinto Bartelochi A ...... 124 Righetto L ...... 78 Osudar R ...... 330 Piontek J ...... 141 Rinaldo A ...... 78 Ouillon N ...... 97 Piraino S ...... 204 Riseman S ...... 219 Ovanesov K ...... 32 Pistocchi R ...... 127 Rissanen A ...... 43 Overmann J ...... 145; 180; 345 Pitta P ...... 121 Rivers AR ...... 84 Piwosz K ...... 231 Rizzo C ...... 241 Paczkowska J ...... 113; 125 Pizzolante G ...... 205; 206; 300 Rizzo L ...... 206 Pala C ...... 190 Plante C ...... 316 Robert R ...... 253 Palesse S ...... 354 Plechuk S ...... 324 Robinson CT ...... 119 Pallavicini A ...... 33; 252; 301 Polesello S ...... 152 Rochelle-Newall E ...... 142; 339; 353 Palovaara J ...... 38; 42; 81 Pollet T ...... 213 Rocher V ...... 379 Pantoja S ...... 129 Polónia A ...... 186; 308 Rochow J ...... 93 Papale M ...... 162; 191 Polz M ...... 181 Rodríguez-Martínez S ...... 370 Parada C ...... 114 Pommier T ...... 101; 142 Rofner C ...... 197 Paranhos R ...... 71 Porporato EMD ...... 241 Rogers AD ...... 307 Paretti P ...... 33 Posch T ...... 51; 55; 111; 126; 352 Rogge A ...... 349 Parisot N ...... 275 Poulton NJ ...... 82; 294 Roguet A ...... 376; 382 Paroncini P ...... 368 Powell A ...... 374 Rohde M ...... 268 Parvathi A ...... 347 Powll S ...... 239 Rolf D ...... 303 Paskauskas R ...... 360 Pradella S ...... 268 Roll K ...... 54 Pasquaroli S ...... 368; 381 Prestegard S ...... 359 Romac S ...... 385 Paterson J ...... 93; 267 Pringault O ...... 276; 339 Romaní AM ...... 26; 88; 326 Patrolecco L ...... 152 Probandt D ...... 32 Romano A ...... 282 Patzelt D ...... 268 Proia L ...... 198 Rösel S ...... 143 Paul J ...... 73 Pruzzo C ...... 271; 380 Rossetti S ...... 167 Peaudecerf F ...... 65; 122 Pujo-Pay M ...... 346 Rosso C ...... 36 Pecellin M ...... 76; 370 Roudnew B ...... 299 Pedros-Alio C ...... 101; 181 Quatrini P ...... 317; 333 Rowe O ...... 113; 125 Peduzzi P ...... 249 Quero GM ...... 375 Rubio Portillo E ...... 144 Peduzzi R ...... 195 Quince C ...... 292; 302 Rud Y ...... 377 Peerakietkhajorn S ...... 269 Quinton SJ ...... 267 Ruiz-González C ...... 198; 199 Pelejero C ...... 42; 81 Rusconi R ...... 66 Penalver C ...... 144 Radeke S ...... 327 Russo D ...... 165 Pereira C ...... 357; 358 Radomski N ...... 382 Rusznyak A ...... 62 Pereira DA ...... 220 Raes J ...... 296

394 Sharma AK ...... 146 Steinberg P ...... 94; 188 Saad M ...... 376 Sharma S ...... 73; 238 Steiner P ...... 97 Saadoun I ...... 332 Shenoy D ...... 261 Stepanauskas R .... 32; 82; 85; 104; 294 Sabart M ...... 230 Shiah FK ...... 179 Stepanauskas S ...... 72 Sabater S ...... 118; 198 Siebert C ...... 59 Stingl U ...... 185 Sabry S ...... 259 Sieczko A ...... 249 Stocker R ...... 66; 67; 112 Sabry SA ...... 266 Sieracki M ...... 294 Stockley L ...... 374 Sachdeva R ...... 176 Sievert S ...... 289 Stolle C ...... 148 Sakmaryova I ...... 334 Silva N ...... 218; 222 Stomp M ...... 36 Sala MM ...... 49; 200 Silva YJ ...... 357; 358 Stora G ...... 163; 164 Salazar G ...... 42; 80; 170; 176; 198 Simek K48; 106; 178; 242; 311; 329; 330 Storesund JE ...... 250; 359 Salcher MM ...... 51; 55; 111; 352 Sime-Ngando T ...... 353; 354 Störmer R ...... 100 Salgado P ...... 287; 291 Simm J ...... 312 Stougaard P ...... 272 Salter I ...... 30 Simon J ...... 145 Streten-Joyce C ...... 137 Sanchez A ...... 171 Simon M ...... 69; 221; 303 Striebel M ...... 194 Sanchez N ...... 222; 225 Simons KL ...... 299 Strunjak-Perović I ...... 321 Sandaa RA ...... 359 Sinclair L ...... 201 Subramanian TA ...... 223 Sandoval R ...... 297 Singer G ...... 95; 278; 302 Sulcius S ...... 360 Santisi S ...... 317; 333 Singh RN ...... 146 Sullam K ...... 161 Santoferrara L ...... 110 Singh RP ...... 146 Sunagawa S ...... 296 Santoro A ...... 284 Sinninghe Damsté JS ...... 210 Suresha HR ...... 149 Santos E ...... 140 Sintes E ...... 80; 97; 156; 257 Suter E ...... 28 Santos GA ...... 338 Sjödin A ...... 371 Suwa S ...... 320 Santos L ...... 318 Sjöstedt J ...... 87; 314 Suwa Y ...... 60 Santos RS ...... 33 Sklorz K ...... 159 Suzuki S ...... 166; 211; 263; 320 Sarmento H ...... 80 Smari-Bjarnason B ...... 292 Svensson L ...... 81 Satinsky B ...... 73 Smiraglia C ...... 31 Swan B ...... 82; 294 Sauerborn Klobucar R ...... 321 Smith AG ...... 65; 122 Swan BR ...... 104 Sauret C ...... 174; 346 Smith C ...... 73; 238 Swarup S ...... 94; 207; 212 Saxena G ...... 94; 207 Smith RJ ...... 138; 299; 341 Syväranta J ...... 43; 237 Scanlan D ...... 40 Smith-Harding TJ ...... 232 Székely A ...... 99 Scardala S ...... 229 Socal G ...... 151 Szelag-Wasielewska E ...... 226 Scherwaß A ...... 159 Sol Souza M ...... 41 Schleper C ...... 173 Sommaruga R24; 45; 197; 245; 285; 343 Tada Y ...... 224 Schouten S ...... 210 Son K ...... 66 Tagliaferri I ...... 31 Schreiber F ...... 96 Song HG ...... 147 Taib N ...... 283 Schubert CJ ...... 129 Sooyeon P ...... 153 Tall A ...... 77 Schulz KG ...... 141; 148 Sorensen SJ ...... 254 Tallarmin A ...... 346 Schulz S ...... 268 Soued C ...... 183 Tanaka T ...... 130 Schulze I ...... 62 Souffreau C ...... 202 Tandoi V ...... 167 Schuster S ...... 212 Speck PG ...... 299 Tangherlini M ...... 277 Schweikert M ...... 55 Sperling M ...... 141 Taniguchi A ...... 224 Schwieder H ...... 248 Spieck E ...... 177 Tanita I ...... 320 Schwientek P ...... 82 Spring S ...... 288 Tanner EJ ...... 267 Scorrano S ...... 204 Spröer C ...... 288 Tara-Oceans Consortium ...... 296 Scranton M ...... 28 Sriram PRA ...... 347 Tarran G ...... 40 Sczyrba A ...... 82 Sriram PRS ...... 354 Tatangelo V ...... 31 Seehausen O ...... 161 Srivastava A ...... 335 Taylor BR ...... 149 Seifried J ...... 319 Srivastava AK ...... 146 Taylor G ...... 28 Sekikawa T ...... 378 Stabili L ...... 203; 204; 205; 206; 300 Teesdale-Spittle P ...... 306 Serkebaeva Y ...... 348 Stal L ...... 36 Teira E ...... 80; 176; 208 Servais P ...... 39; 379 Stal LJ ...... 305 Terrisse F ...... 164 Seuront L ...... 108; 138 Staniulis J ...... 360 Thamdrup B ...... 107 Sevcu A ...... 334 Stauder M ...... 271 Thelaus J ...... 75; 371 Seymour JR . 66; 67; 108; 138; 184; 299 Stauffert M ...... 163 Therial C ...... 376; 379 Shabarova T ...... 92 Steenbergh A ...... 70 Thingstad TF ...... 250; 359 Shakya S ...... 93 Stefanelli M ...... 229 Thomas D ...... 25 Shapiro OH ...... 66 Stefani S ...... 324 Thomas F ...... 289 Sharaby Y ...... 370 Stefanni S ...... 33 Thompson BP ...... 82

395 Thompson C ...... 71 Vaqué D ...... 80 Wilson R ...... 239 Thompson F ...... 71 Varela MM ...... 176; 208 Wincker P ...... 296 Thu TD ...... 142 Vargas CA ...... 218 Winn K ...... 361 Thupham T ...... 339 Vasquez-Cardenas D ...... 336 Winter C ...... 103; 351 Tiirola M ...... 43 Vaz L ...... 318 Wöbken D ...... 35 Tillmann L ...... 190 Vaz N ...... 318 Wong S ...... 166; 211 Timoner X ...... 118 Vezzulli L ...... 271; 380 Wos-Oxley M ...... 297 Tinta T ...... 150 Vidal C ...... 156 Woyke T ...... 82 Toan TD ...... 142 Vignaroli C ...... 368; 381 Wright JJ ...... 82 Tomasch J ...... 268; 297 Vila-Costa M ...... 42; 81 Wuertz S ...... 94 Tonolla M ...... 195; 236 Vilar-Sanz A ...... 116 Wurzbacher C ...... 280 Topić Popović N ...... 321 Villanueva L ...... 210 Wylezich C ...... 337 Torky Y ...... 123 Villiger J ...... 92; 337 Torreton JP ...... 339 Vitale E ...... 323 Yager P ...... 73 Totsche KU ...... 62 Vladimir K ...... 114 Yager PL ...... 101 Touron-Bodilis A ...... 77 Voelcker NH ...... 108 Yakimov MM ...... 165; 317; 333 Tout J ...... 66; 67 Voget S ...... 69; 221 Yanagawa K ...... 251 Trampe E ...... 272 Vogts A ...... 349 Yarza P ...... 144 Tran QH ...... 353 Volant A ...... 310 Yissue W ...... 94 Tredici SM ...... 206; 300 Volkenborn N ...... 74 Ylla I ...... 26 Trento I ...... 151 Yokokawa T ...... 246; 251 Triadó-Margarit X ...... 39 Wagley S ...... 374 Yonghui Z ...... 178 Triana C ...... 282 Wagner K ...... 47; 302 Yoshizawa S ...... 331 Trias R ...... 116 Wagner-Döbler I ...... 268; 297 Youssef T ...... 325 Trimble L ...... 282 Walsh D ...... 183 Youssif EM ...... 266 Trottet A ...... 188 Wanek W ...... 47 Yu JE ...... 262 Tsiola A ...... 121 Wang H ...... 268; 297 Yung PY ...... 212 Tsukada K ...... 269 Wang KW ...... 179 Tupper B ...... 82 Ward JE ...... 192 Zaghmouri I ...... 157 Turk V ...... 150; 204; 265 Warnecke F ...... 50 Zaman R ...... 78 Tuyet DTA ...... 130 Washington V ...... 313 Zaremba K ...... 85 Watanabe H ...... 269 Zeder M ...... 274 Uchimiya M ...... 263 Weber B ...... 338 Zeng Y ...... 290 Umashankar S ...... 212 Wefer H ...... 293 Zhao X ...... 192 Uranga A ...... 209 Wegner M ...... 74 Zhong X ...... 347; 362 Urvois F ...... 256 Wei TJ ...... 94 Zhou J ...... 207 Weinmaier T ...... 173 Ziegler A ...... 172 Vage S ...... 250 Wemheuer B ...... 69; 221 Zielinski B ...... 73 Valentin J ...... 71 Wendling C ...... 74 Znachor P ...... 311 van Beusekom S ...... 36 Wenzhöfer F ...... 117; 129 Zoccarato L ...... 252; 301 van Chu T ...... 339 Wichels A ...... 100; 315; 319 Zoppini A ...... 152; 193 van der Zaan B ...... 70 Wiebe WJ ...... 291 Zubkov M ...... 40 Van Wambeke F ...... 120 Wilhelm L ...... 95; 278; 302 Zwielehner J ...... 338 Vandieken V ...... 107 Williams R ...... 187 Vanucci S ...... 127 Williams RBH ...... 94

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