DOCSLIB.ORG

Microbial Degradation and Ecological Impacts of Biodegradable Plastic Mulch Films in Agricultural Soils

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Microbial Degradation and Ecological Impacts of Biodegradable Plastic Mulch Films in Agricultural Soils University of Tennessee, Knoxville TRACE: Tennessee Research and Creative Exchange Doctoral Dissertations Graduate School 12-2019 Microbial Degradation and Ecological Impacts of Biodegradable Plastic Mulch Films in Agricultural Soils Sreejata Bandopadhyay University of Tennessee, [email protected] Follow this and additional works at: https://trace.tennessee.edu/utk_graddiss Recommended Citation Bandopadhyay, Sreejata, "Microbial Degradation and Ecological Impacts of Biodegradable Plastic Mulch Films in Agricultural Soils. " PhD diss., University of Tennessee, 2019. https://trace.tennessee.edu/utk_graddiss/5682 This Dissertation is brought to you for free and open access by the Graduate School at TRACE: Tennessee Research and Creative Exchange. It has been accepted for inclusion in Doctoral Dissertations by an authorized administrator of TRACE: Tennessee Research and Creative Exchange. For more information, please contact [email protected]. To the Graduate Council: I am submitting herewith a dissertation written by Sreejata Bandopadhyay entitled "Microbial Degradation and Ecological Impacts of Biodegradable Plastic Mulch Films in Agricultural Soils." I have examined the final electronic copy of this dissertation for form and content and recommend that it be accepted in partial fulfillment of the equirr ements for the degree of Doctor of Philosophy, with a major in Environmental and Soil Sciences. Jennifer DeBruyn, Major Professor We have read this dissertation and recommend its acceptance: Sean Schaeffer, Douglas Hayes, Todd Reynolds Accepted for the Council: Dixie L. Thompson Vice Provost and Dean of the Graduate School (Original signatures are on file with official studentecor r ds.) Microbial Degradation and Ecological Impacts of Biodegradable Plastic Mulch Films in Agricultural Soils A Dissertation Presented for the Doctor of Philosophy Degree The University of Tennessee, Knoxville Sreejata Bandopadhyay December 2019 Copyright © 2019 by Sreejata Bandopadhyay. All rights reserved. ii DEDICATION I dedicate this work to my grandfather, Late Mr. Sudhindra Mohan Banerjee; my parents Mrs. Archita Bandopadhyay and Mr. Satyaban Bandopadhyay; and my sister Amrita. Intellectuals in their own right, my grandfather and my parents have had a profound influence on my educational journey. My grandfather was not only my mentor and science tutor all through my high school, but his influence has shaped me in many ways to be the person I am today. My path to graduate school in the US would not have been successful without the support and encouragement of my loving parents who have taught me that there is no substitute for hard work and those who are true to themselves will always succeed. This is for you. iii ACKNOWLEDGEMENTS First, I would like to thank my mentor, Dr. Jennifer DeBruyn, for giving me an opportunity to join her lab and pursue my doctoral studies. Her patience, encouragement, and guidance throughout this project has been instrumental in achieving this degree. Being an international student and living so far away from home, I have been fortunate to have had Dr. DeBruyn as an understanding and kind advisor. I would also like to thank my dissertation committee members - Dr. Douglas Hayes, Dr. Sean Schaeffer and Dr. Todd Reynolds - for their suggestions, constructive criticism and critical inputs that led to the successful completion of this project. I am much more confident and curious because of the influence of each one of you. My sincere gratitude to the Department of Biosystems Engineering and Soil Science at the University of Tennessee - its students, staff and faculty. This department has not only provided me with a platform for mentorship and exchange of scientific knowledge, but I have made life-long connections and friendships with people who have gone out of their way to help me when I needed them. Next, I would like to thank the Biodegradable Mulch Project Team at the University of Tennessee and Washington State University. I find myself fortunate to have worked with this team as it has given me a unique opportunity of transdisciplinary collaboration. Because of this project, I have worked with scientists and students from diverse disciplines and have learnt to see my own research in the context of and in relation to theirs. I thank my peers in this project, Marie English and Jose Liquet Gonzalez, for always being there for me; their friendship is something I will cherish beyond the realm of graduate school. My heartfelt gratitude to my friends in Knoxville who helped me through all the highs and lows by being my lifelines here and making Knoxville my second home. Rahul, Divyani, Avik, and Rani – I cannot thank you all enough for the support and love you gave me and for the amazing friendships I share with each one of you. Last, but not the least, I thank my parents and sister for their wisdom, inspiration and faith in me which motivates me to do better. And finally, to Tanmoy, for his unconditional support and unwavering belief in me. iv “Nothing in life is to be feared, it is only to be understood. Now is the time to understand more, so that we may fear less.” -Marie Curie (1867-1934) v ABSTRACT Agricultural plastic mulch films are used to improve crop yields by reducing weeds, moderating soil temperature and conserving soil moisture. Unfortunately, increased popularity of polyethylene (PE) mulch films have resulted in widespread pollution because they are non-biodegradable and have limited recycling options. Biodegradable plastic mulch films (BDMs) are emerging as a sustainable alternative to PE films. BDMs are meant to be tilled into the soil where they are expected to fully biodegrade. However, the biodegradation process is slow, and fragments can persist in soil for months. Limited research regarding the impacts of BDMs on soil microbial communities, and inadequate information on BDM-degrading microbes and factors that control biodegradation of BDMs have restricted their adoption. The objectives of this study were to 1) evaluate the effects of BDMs and PE on soil microbial community structure and function over two years (Spring 2015 - Spring 2017) in two geographical locations: Knoxville, TN, and Mount Vernon, WA, 2) identify potential BDM-degrading microbes using field and laboratory enrichment studies, and 3) evaluate the impacts of added nitrogen amendments on microbial decomposition of BDMs. Bacterial community structure and function were determined using 16S rRNA amplicon sequencing of soil DNA and extracellular enzyme assays. Microbial community structure and function differed between TN and WA (p < 0.05), and seasons of sampling within each location (p < 0.05); however, mulch treatment differences were not significant (p > 0.05). Microbial communities adhered to field-weathered BDMs (the plastic-ome) demonstrated enrichment of soil microbial taxa. Sequence data from BDMs in lab enrichments and isolates demonstrated that microbial colonization on the BDMs was driven by the composition of the mulch films. BDM decomposition was observed in soil microcosms with and without nitrogen amendments. However, nitrogen amendments to BDMs resulted in reduced mulch decomposition. Nevertheless, addition of mulch had minimal impacts on nitrification processes and enzyme activities in the microcosms, irrespective of nitrogen amendments. Limited effects of BDMs on soil microbial community structure and function suggest that BDMs may be a viable alternative to PE. The initial characterization of the “plastic-ome” lays a strong groundwork for future research on microbes degrading BDMs. vi TABLE OF CONTENTS INTRODUCTION ..................................................................................................... 1 Research questions .................................................................................................. 2 Organization of the dissertation .............................................................................. 2 CHAPTER I LITERATURE REVIEW .......................................................................................... 3 Plastic film mulching in agriculture ....................................................................... 3 Benefits of plastic mulch films ............................................................................... 4 Negative impacts of conventional polyethylene (PE) plastic ................................. 5 Alternatives to polyethylene (PE) mulches: The shift towards biodegradable mulches .................................................................................................................10 Paper based mulches ..........................................................................................10 Photodegradable mulches ..................................................................................11 Oxo-degradable mulches ...................................................................................12 Biodegradable plastic mulches (BDMs) ............................................................13 Microbial degradation of BDMs ...........................................................................16 Microbial colonization of BDM surface ............................................................17 Enzymatic degradation of BDM polymers ........................................................17 Microbial utilization of degradation products ...................................................31 Knowledge gap ..................................................................................................32 Characterizing
Load more

Recommended publications
  • Alternatives to Plastic Mulch
    Alternatives to Plastic Mulch for Organic Vegetable Production Carol Miles, Kathryn Kolker, Jenn Reed and Gail Becker WSU Vancouver Research & Extension Unit 1919 NE 78th Street, Vancouver, WA 98665 (360) 576-6030, [email protected], http://agsyst.wsu.edu Introduction Weed control is one of the primary concerns in organic farming as it is labor intensive, expensive and time consuming. Since its introduction in the 1950s, plastic mulch has become a standard practice used by many farmers to control weeds, increase crop yield, and shorten time to harvest (Lamont, 1991). Plastic mulch has contributed significantly to the economic viability of farmers worldwide, and by 1999 almost 30 million acres worldwide were covered with plastic mulch, with more than 185,000 of those acres in the United States (American Plastics Council, 2004; Takakura and Fang, 2001). However, each year farmers must dispose of their plastic, and although agricultural plastic recycling has begun, the disposal option that most choose is the landfill (Garthe, 2002). Many organic farmers, especially those who are small-scale, choose not to use plastic mulch because of the waste disposal issues. An effective, affordable, degradable alternative to the now-standard plastic mulch would contribute the same production benefits as plastic mulch and in addition would reduce non-recyclable waste. Previous work. In 2003, we conducted a preliminary study at Washington State University Vancouver Research and Extension Unit (WSU VREU) to evaluate paper and cornstarch mulches as alternatives to plastic mulch. We used 81 lb Kraft paper with and without oil application. We evaluated three oils (soybean, linseed and tung) applied before and after laying the paper.
    [Show full text]
  • AGRICULTURAL PLASTICS Q & a Vers Feb 8, 2016
    Lois Levitan, PhD Recycling Agricultural Plastics Program Department of Communication Cornell University, Ithaca NY 14853 AGRICULTURAL PLASTICS Q & A vers Feb 8, 2016 • What are agricultural plastics? • What is plastic? • How is plastic film used on dairy farms? • How is plastic film used in producing fruits, vegetables & ornamentals? • What is done with waste plastic after it is no longer useful on the farm? • What new products are made from recycled agricultural plastics? • Why is plastic ground up or baled before shipping to markets? • Are all agricultural plastics made from the same material? • Is it ok to burn waste plastic in a back field on the farm? • What about pesticide containers? WHAT ARE AGRICULTURAL PLASTICS? ‘Agricultural Plastics’ are the array of plastic products and packaging used in agricultural production and sales. Most have a short useful life. Plastic products are typically lighter to lift and transport, less fragile, safer to use, and have a higher production efficiency than the concrete, glass, ceramic and other materials they have replaced over the past several decades. Silage Bags • Bunk Silo Covers • Polytwine • Bale Wrap • Netwrap • Maple Tubing • Irrigation Drip Tape & Polytubes • High Tunnels • Tarps • Seedling Plug Trays • Plant Pots • Mulch Film • Fumigation Film • Pesticide & Dairy Chemical Containers • Boat Wrap • Bee Hive Frames • Bird Netting • Aquaculture Supplies • Row Covers • O2 & Moisture-Barrier Film • Bags for Seed, Feed, Fertilizer, Peat, Wood Pellets, Potting Mix, etc. • Low Tunnels • • F.I.B.C. (totes, supersacks) • Grain Bags • Greenhouse Covers • Hoophouses • Solarization Film • WHAT IS PLASTIC? Plastics are solid materials that can be molded, pressed, or extruded into a variety of forms and shapes.
    [Show full text]
  • COT Microplastics Overarching Staement 2021
    COMMITTEE ON TOXICITY OF CHEMICALS IN FOOD, CONSUMER PRODUCTS AND THE ENVIRONMENT Overarching statement on the potential risks from exposure to microplastics Background 1. Plastic pollution has been widely recognised as a global environmental problem (Villarrubia-Gómez et al., 2018). The adverse effects of plastic litter have been widely documented for marine animals (e.g. entanglement, ingestion and lacerations); however, the potential risks from exposure to smaller plastic particles i.e. micro- and nanoplastics in humans are yet to be fully understood. Scope and purpose 2. As part of horizon scanning, the Committee on Toxicity of Chemicals in Food, Consumer Products and the Environment (COT) identified the potential risks from microplastics as a topic it should consider. Upon review of the literature, it was decided that nanoplastics should also be included. An initial scoping paper was presented to the COT in October 2019 (TOX/2019/62)1, since when the topic and additional information has been discussed several times by COT with the final substantive discussion in December 2020. A list of all discussion papers considered by the COT during the review is given in Annex A. 3. The purpose of this overarching statement is to bring together these discussions, summarise the COT conclusions reached to date and provide a high-level overview of the current state of knowledge, data gaps and research needs with regards to this topic. 4. Future sub-statements, which will consider in detail the potential toxicological risks of exposure from microplastics via the oral and inhalation routes, are intended to provide supplementary material for this overarching statement.
    [Show full text]
  • Plasticulture in California Vegetable Production
    PUBLICATION 8016 Plasticulture in California Vegetable Production WAYNE L. SCHRADER, UC Cooperative Extension Vegetable Farm Advisor, San Diego County Plasticulture is the art of using plastic materials to modify the production environ- UNIVERSITY OF ment in vegetable crop production. Plasticulture began in the 1950s and early 1960s with the introduction and use of plastic films, mulches, and drip irrigation systems. CALIFORNIA Vegetable growers frequently use plastics in pest management, stand establishment, Division of Agriculture harvesting, and postharvest handling operations, and in containers for marketing. and Natural Resources Plasticulture system components can include http://anrcatalog.ucdavis.edu • plastic mulches to control soil temperature, control weeds, and repel insects • plastic films for erosion control, soil fumigation, or solarization • row covers for temperature control, wind or frost protection, and insect exclusion • drip irrigation for improved water management and for the application of chemi- cals (chemigation) and fertilizers (fertigation) during irrigation • plastic windbreaks • plastic barriers against vertebrate pests Plasticulture has developed into management systems that allow growers to achieve higher-quality produce, superior yields, and extended production cycles. Growers using plasticulture can produce vegetables for markets during the winter, early spring, and late fall that would otherwise be impossible to address. Benefits of plasticulture include • earlier production (7 to 30 days earlier) • increased
    [Show full text]
  • Paper-Based Products As Promising Substitutes for Plastics in the Context of Bans on Non-Biodegradables
    EDITORIAL bioresources.com Paper-based Products as Promising Substitutes for Plastics in the Context of Bans on Non-biodegradables Wei Liu,a,# Huayu Liu,a,# Kun Liu,a,# Haishun Du,b,* Ying Liu,c and Chuanling Si a,c,* As a global environmental problem, plastic pollution has attracted worldwide attention. Plastic wastes not only disrupt ecosystems and biodiversity, but they also threaten human life and health. Countries around the world have enacted regulations in recent years to limit the use of plastics. Paper products have been proposed as promising substitutes for plastics, which undoubtedly brings unprecedented opportunities to the pulp and paper industry. However, paper products have some deficiencies in replacing certain plastic products. Research and development to improve paper properties and reduce production costs is needed to meet such challenges. Keywords: Plastic; Plastic bans; Pulp and paper industry; Paper-based materials Contact information: a: Tianjin Key Laboratory of Pulp and Paper, Tianjin University of Science and Technology, Tianjin 300457, China; b: Department of Chemical Engineering, Auburn University, Auburn, AL 36849, USA; c: Tianjin Jianfeng Natural Product R&D Co., Ltd., Tianjin 300457, China; *Corresponding authors: [email protected]; [email protected] # Co-first author with the same contribution to this work Plastics and Plastic Bans Plastic products have the advantages of light weight, low cost, good ductility, and excellent insulation, which explains why they have been widely used in industry, agriculture, medicine, and other fields (Geyer et al. 2017). Over the past few decades, the production of plastics has experienced rapid growth. It is reported that by 2015, 8.3 billion tons of plastics had been produced in the world; however, of that amount, 6.3 billion tons had become plastic waste (Geyer et al.
    [Show full text]
  • Allowed Mulches on Organic Farms and the Future of Biodegradable Mulch
    Allowed Mulches on Organic Farms and the Future of Biodegradable Mulch All farmers know that conventional polyethylene (aka: plastic) mulch is widely used for crop production because it controls weeds, conserves soil moisture, increases soil temperature, improves crop yield and quality, has a relatively low cost, and is readily available. Conventional mulch is also widely used on organic farms although organic farmers and others have questioned its use because it is often non- recyclable, and is generally made from non-biodegradable based materials. At this time, no biodegradable mulch is allowed for use on organic farms. None of the commercially available biodegradable mulches have been proven to meet the requirements of the National Organic Standards. In this document we answer common questions about the currently allowed mulches on organic farms and the potential of using biodegradable mulches in the future. How does the National Organic Program define “mulch”? 7 CFR 205.2 The National Organic Program (NOP) states that mulch is any non-synthetic material, such as wood chips, leaves, or straw, or any allowed synthetic material such as newspaper or plastic that serves to suppress weed growth, moderate soil temperature, or conserve soil moisture. What specifically can organic farmers use now for mulching? 7 CFR 205.601 Currently allowed options for mulching are: • Non-synthetic, untreated materials such as wood chips, leaves, or straw • Newspapers or other recycled paper, without gloss, glossy inks, or color inks • Plastic mulches and covers provided they are removed from the field at the end of the growing season, and they are petroleum-based, but not polyvinyl chloride (PVC) • Biodegradable bio-based mulch film - provided that it complies with the requirements and restrictions of the USDA organic regulations, and Policy Memo 15-1 in the NOP Program Handbook.
    [Show full text]
  • And Microplastics on an Agricultural Farmland Received: 31 May 2018 Sarah Piehl 1, Anna Leibner1, Martin G
    www.nature.com/scientificreports OPEN Identifcation and quantifcation of macro- and microplastics on an agricultural farmland Received: 31 May 2018 Sarah Piehl 1, Anna Leibner1, Martin G. J. Löder 1, Rachid Dris 1, Christina Bogner 2 & Accepted: 8 November 2018 Christian Laforsch 1 Published: xx xx xxxx Microplastic contamination of aquatic ecosystems is a high priority research topic, whereas the issue on terrestrial ecosystems has been widely neglected. At the same time, terrestrial ecosystems under human infuence, such as agroecosystems, are likely to be contaminated by plastic debris. However, the extent of this contamination has not been determined at present. Via Fourier transform infrared (FTIR) analysis, we quantifed for the frst time the macro- and microplastic contamination on an agricultural farmland in southeast Germany. We found 206 macroplastic pieces per hectare and 0.34 ± 0.36 microplastic particles per kilogram dry weight of soil. In general, polyethylene was the most common polymer type, followed by polystyrene and polypropylene. Films and fragments were the dominating categories found for microplastics, whereas predominantly flms were found for macroplastics. Since we intentionally chose a study site where microplastic-containing fertilizers and agricultural plastic applications were never used, our fndings report on plastic contamination on a site which only receives conventional agricultural treatment. However, the contamination is probably higher in areas where agricultural plastic applications, like greenhouses, mulch, or silage flms, or plastic-containing fertilizers (sewage sludge, biowaste composts) are applied. Hence, further research on the extent of this contamination is needed with special regard to diferent cultivation practices. Plastic debris is ubiquitous in all ecosystems on earth1 and yet, only a fraction of this environmental issue is visi- ble.
    [Show full text]
  • Black Polypropylene Non-Woven Textile As Mulch in Organic Agriculture
    II 38 I BIOACADEMY 2009 BLACK POLYPROPYLENE NON-WOVEN TEXTILE AS MULCH IN ORGANIC AGRICULTURE DVORAK, P." HAMOUZ, K." KUCHTOvA, P." TOMAsEK, J. 1 & ERHARTOvA, 0,1 Key words: polypropylene black mulch, soil temperature, soil water potential, weed Abstract Black polypropylene textile was used in potatoes by organic agriculture and it had positive effect on soil temperature (in the depth of 100 mmJ. Slightly higher soil temperatures under black polypropylene mulch in the vegetation oeriod after planting had favourable influence on stands emergence. The water potential depth of250 and also ~vater content have been beneficial for black polypropylene mulch. Signihcantly IO'Ner values the water potentials have been found in the period after planting and at the ofvegetation. Black polyprooylene mulch provided favourable temperatures and soil moisture. Introduction Black polyethylene mulches are used for weed control in a range of crops under the organic system. The use of black polypropylene woven mulch is usually restricted to perennial crops. Various colours of woven and solid film plastics have been tested for weed control in the field (Horowitz, 1993). White and green covering had little effect on weeds, whereas brown, black, blue or white on black (double colour) films prevented weeds emerging (Bond and Grundy, 2001). There are additional environmental benefits if the mulch is made from recycled materials (Cooke, 1996). Aim of this research was found favourable growing procedure of the potatoes in organic agriculture. Foil or black mulches textile reduce weed biomass, increase soil temperature and soil water content but their application in praxis is exacting. Materials and methods The trial was conducted in year 2008 at Experimental station of Department of Crop Production of the Czech University of life Science Prague-Uhffneves.
    [Show full text]
  • Bio-Based and Biodegradable Plastics – Facts and Figures Focus on Food Packaging in the Netherlands
    Bio-based and biodegradable plastics – Facts and Figures Focus on food packaging in the Netherlands Martien van den Oever, Karin Molenveld, Maarten van der Zee, Harriëtte Bos Rapport nr. 1722 Bio-based and biodegradable plastics - Facts and Figures Focus on food packaging in the Netherlands Martien van den Oever, Karin Molenveld, Maarten van der Zee, Harriëtte Bos Report 1722 Colophon Title Bio-based and biodegradable plastics - Facts and Figures Author(s) Martien van den Oever, Karin Molenveld, Maarten van der Zee, Harriëtte Bos Number Wageningen Food & Biobased Research number 1722 ISBN-number 978-94-6343-121-7 DOI http://dx.doi.org/10.18174/408350 Date of publication April 2017 Version Concept Confidentiality No/yes+date of expiration OPD code OPD code Approved by Christiaan Bolck Review Intern Name reviewer Christaan Bolck Sponsor RVO.nl + Dutch Ministry of Economic Affairs Client RVO.nl + Dutch Ministry of Economic Affairs Wageningen Food & Biobased Research P.O. Box 17 NL-6700 AA Wageningen Tel: +31 (0)317 480 084 E-mail: [email protected] Internet: www.wur.nl/foodandbiobased-research © Wageningen Food & Biobased Research, institute within the legal entity Stichting Wageningen Research All rights reserved. No part of this publication may be reproduced, stored in a retrieval system of any nature, or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording or otherwise, without the prior permission of the publisher. The publisher does not accept any liability for inaccuracies in this report. 2 © Wageningen Food & Biobased Research, institute within the legal entity Stichting Wageningen Research Preface For over 25 years Wageningen Food & Biobased Research (WFBR) is involved in research and development of bio-based materials and products.
    [Show full text]
  • Commercial Vegetable Production with Plastic Mulches
    Commercial Vegetable Cooperative Extension Service College of Agriculture and Production With Home Economics Plastic Mulches Guide H-245 George W. Dickerson, Extension Horticulture Specialist This publication is scheduled to be updated and reissued 12/07. In New Mexico, growing vegetables commercially, yields. Black plastic mulch can accelerate crop whether for vegetable sheds or farmers’ markets, re- production as much as one to two weeks. Clear quires intensive management and marketing skills. plastic mulch has been shown to increase earli- Success involves properly managing scarce water ness as much as three weeks in northern cli- supplies, controlling weeds and other pests and sup- mates. Weed growth, however, can be a major plying a high-quality product when the price is high. problem under clear plastic unless appropriate High prices generally are associated with limited sup- herbicides or fumigants are used. Selecting the ply and high demand. crop type (vine crops like pumpkins, squash, melons) also is important in warmer areas of Mulches the state for good ground cover or shading in the summer to prevent excessive heat build up un- Mulching is an agricultural cropping technique that der the plastic. involves placing organic or synthetic materials on the • Reduced evaporation. Plastic mulches help re- soil around plants to provide a more favorable envi- duce evaporation of moisture from the soil. Irri- ronment for growth and production. Organic mulches gation frequency and amounts generally can be traditionally are used in backyard gardens and smaller reduced, although additional water may be truck gardening operations, since materials may be needed to support earlier and greater crop pro- limited and application techniques are labor intensive.
    [Show full text]
  • Aerobic Anoxygenic Photosynthesis Genes and Operons in Uncultured Bacteria in the Delaware River
    Blackwell Science, LtdOxford, UKEMIEnvironmental Microbiology 1462-2912Society for Applied Microbiology and Blackwell Publishing Ltd, 200571218961908Original ArticleDelaware River AAP bacteriaL. A. Waidner and D. L. Kirchman Environmental Microbiology (2005) 7(12), 1896–1908 doi:10.1111/j.1462-2920.2005.00883.x Aerobic anoxygenic photosynthesis genes and operons in uncultured bacteria in the Delaware River Lisa A. Waidner and David L. Kirchman* AAP bacteria photosynthesize with the use of bacterio- University of Delaware, College of Marine Studies, 700 chlorophyll a (bchl a), but do not evolve oxygen (Yurkov Pilottown Road, Lewes, DE 19958, USA. and Beatty, 1998). A more thorough understanding of AAP bacteria is needed to elucidate their role in aquatic environments. Summary The diversity of marine AAP bacteria is often explored Photosynthesis genes and operons of aerobic anox- with the gene encoding the alpha subunit of the photosyn- ygenic photosynthetic (AAP) bacteria have been thetic reaction centre, puf M (Beja et al., 2002; Oz et al., examined in a variety of marine habitats, but genomic 2005; Schwalbach and Fuhrman, 2005). On the basis of information about freshwater AAP bacteria is lacking. puf M, AAP bacteria have been classified into two clusters The goal of this study was to examine photosynthesis of proteobacteria (Nagashima et al., 1997). One consists genes of AAP bacteria in the Delaware River. In a of a mixture of alpha-1 and alpha-2, beta- and gamma- fosmid library, we found two clones bearing photo- proteobacteria, referred to here as the ‘mixed cluster’ synthesis gene clusters with unique gene content and (Nagashima et al., 1997). The other cluster contains the organization.
    [Show full text]
  • Roseateles Depolymerans Gen. Nov., Sp. Nov., a New Bacteriochlorophyll A-Containing Obligate Aerobe Belonging to the P=Subclassof the Pro Teobacteria
    International Journal of Systematic Bacteriology (1 999), 49,449-457 Printed in Great Britain Roseateles depolymerans gen. nov., sp. nov., a new bacteriochlorophyll a-containing obligate aerobe belonging to the P=subclassof the Pro teobacteria Tetsushi Suyama,’ Toru Shigematsu,’ Shinichi Takaichit2 Yoshinobu Nodasakaf3Seizo F~jikawa,~Hiroyuki Hosoya,’ Yutaka Tokiwa,’ Takahiro Kanagawa’ and Satoshi Hanadal Author for correspondence : Tetsushi Suyama. Tel : + 8 1 298 54 659 1. Fax : + 8 1 298 54 6587. e-mail: [email protected] ~~ 1 National Institute of Strains 61AT(T = type strain) and 6IB2, the first bacteriochlorophyll (BChI) a- Bioscience and Human containing obligate aerobes to be classified in the /?-subclassof the Technology, 1-1 Higashi, Tsukuba, lbaraki Profeobacteria, were isolated from river water. The strains were originally 305-8566,Japan isolated as degraders of poly(hexamethy1ene carbonate) (PHC). The organisms * Biological Laboratory, can utilize PHC and some other biodegradable plastics. The strains grow only Nippon Medical School, under aerobic conditions. Good production of BChl a and carotenoid pigments Kawasaki 21 1-0063,Japan is achieved on PHC agar plates and an equivalent production is observed under 3.4 School of Dentistry3 and oligotrophic conditions on agar medium. Spectrometric results suggest that Institute of Low BChl a is present in light-harvesting complex I and the photochemical reaction Temperature Science4, Hokkaido University, centre. The main carotenoids are spirilloxanthin and its precursors. Analysis of Sapporo 060, Japan the 165 rRNA gene sequence indicated that the phylogenetic positions of the two strains are similar to each other and that their closest relatives are the genera Rubriwiwax, ldeonella and Leptothrix with similarities of 96.3, 962 and 96-1%, respectively.
    [Show full text]