DOCSLIB.ORG

Environmental Controls Over Bacterial Communities in Polar Desert Soils 1, 1 2 2 KEVIN M

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Environmental Controls Over Bacterial Communities in Polar Desert Soils 1, 1 2 2 KEVIN M Environmental controls over bacterial communities in polar desert soils 1, 1 2 2 KEVIN M. GEYER, ADAM E. ALTRICHTER, DAVID J. VAN HORN, CRISTINA D. TAKACS-VESBACH, 3,4 1 MICHAEL N. GOOSEFF, AND J. E. BARRETT 1Department of Biological Sciences, Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061 USA 2Department of Biology, University of New Mexico, Albuquerque, New Mexico 87131 USA 3Department of Civil and Environmental Engineering, Pennsylvania State University, University Park, Pennsylvania 16802 USA Citation: Geyer, K. M., A. E. Altrichter, D. J. Van Horn, C. D. Takacs-Vesbach, M. N. Gooseff, and J. E. Barrett. 2013. Environmental controls over bacterial communities in polar desert soils. Ecosphere 4(10):127. http://dx.doi.org/10.1890/ ES13-00048.1 Abstract. Productivity-diversity theory has proven informative to many investigations seeking to understand drivers of spatial patterns in biotic communities and relationships between resource availability and community structure documented for a wide variety of taxa. For soil bacteria, availability of organic matter is one such resource known to influence diversity and community structure. Here we describe the influence of environmental gradients on soil bacterial communities of the McMurdo Dry Valleys, Antarctica, a model ecosystem that hosts simple, microbially-dominated foodwebs believed to be primarily structured by abiotic drivers such as water, organic matter, pH, and electrical conductivity. We sampled 48 locations exhibiting orders of magnitude ranges in primary production and soil geochemistry (pH and electrical conductivity) over local and regional scales. Our findings show that environmental gradients imposed by cryptogam productivity and regional variation in geochemistry influence the diversity and structure of soil bacterial communities. Responses of soil bacterial richness to carbon content illustrate a productivity-diversity relationship, while bacterial community structure primarily responds to soil pH and electrical conductivity. This diversity response to resource availability and a community structure response to environmental severity suggests a need for careful consideration of how microbial communities and associated functions may respond to shifting environmental conditions resulting from human activity and climate variability. Key words: Antarctic Dry Valleys; biogeography; environmental gradients; microbial ecology; productivity/diversity theory. Received 15 February 2013; revised 17 July 2013; accepted 18 July 2013; final version received 17 September 2013; published 25 October 2013. Corresponding Editor: U. Nielsen. Copyright: Ó 2013 Geyer et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. http://creativecommons.org/licenses/by/3.0/ 4 Present address: Department of Civil and Environmental Engineering, Colorado State University, Fort Collins, Colorado 80523 USA. E-mail: geyerkev@vt.edu INTRODUCTION ing a diverse microbial world exhibiting spatial patterns over environmental gradients spanning Despite early suggestions that microbial taxa meter, kilometer (Noguez et al. 2005, Zeglin et al. experience cosmopolitan distribution (Baas Beck- 2011) and regional to continental scales (Fierer ing 1934, Finlay 2002), recent evidence is reveal- and Jackson 2006, Yergeau et al. 2007, Bryant et v www.esajournals.org 1 October 2013 v Volume 4(10) v Article 127 GEYER ET AL. al. 2008). Although geographic patterns in soil organic matter content and extreme ranges of microbial communities are now evident, the soil pH (.9.0) and salinity (.10,000 lS/cm) mechanisms driving them remain poorly under- (Bockheim 1997). Distinct biogeochemical gradi- stood (Soininen 2012). One promising avenue for ents span orders of magnitude in nutrient beginning to frame hypotheses behind microbial availability, major ion concentrations, and bio- biogeography is the application of macroecolog- mass (Barrett et al. 2004, Poage et al. 2008), ical theory, with which researchers may test characteristics of a landscape where abiotic whether controls over the spatial organization factors are the primary controls over the diversity of eukaryotic communities are equally appropri- and structure of microbial communities. Recent ate for microorganisms (Martiny et al. 2006, research conducted in this region has described Soininen 2012). responses of microbial communities to a number Environmental controls have been long recog- of abiotic drivers including: water availability nized as major drivers of a species’ presence/ (Zeglin et al. 2011); geochemistry (Lee et al. absence and abundance (Ricklefs and Schluter 2012); carbon concentration (Aislabie et al. 2009); 1994). For instance, productivity-diversity hy- or a combination of these factors (Niederberger et potheses predict that spatial or temporal varia- al. 2008, Smith et al. 2010, Stomeo et al. 2012). tion in resource availability (e.g., nitrogen, The anticipated response of dry valley biota to organic matter) influences communities by elic- environmental controls is also supported by iting niche-specialization of, and even competi- evidence from other ecosystems and experimen- tive exclusion by, particular species across ranges tal manipulations, which have demonstrated a of nutrient availability or productivity (Tilman community response to environmental variabil- 1982, Waide et al. 1999). Often a unimodal ity, such as positive influences of moisture levels (hump-shaped curve) relationship is observed on diversity (Zhou et al. 2002) and effects on between productivity and diversity, a result of community similarity due to carbon substrate positive effects of resource availability and (resource) diversity (Orwin et al. 2006, Eilers et negative effects of competition along a gradient al. 2010). of increasing ecosystem production (Michalet et Here we focus on the distinct effects of al. 2006). Field surveys (Abramsky and Rose- resource availability on both bacterial communi- nzweig 1984, Mittelbach et al. 2001) and exper- ty diversity and structure, as well as the imental resource manipulations (Silvertown et al. influences of geochemical severity (pH and 2006, Chase 2010) support these predictions for a salinity). To evaluate these abiotic drivers we variety of taxa in terrestrial and aquatic ecosys- studied soils representing a productivity gradient while additionally capturing an extensive range tems. Environmental severity (e.g., extreme pH in geochemical conditions. Based on evidence or salinity) may also generate a range of physical from productivity/diversity theory and other conditions that influences productivity, habitat field surveys, we hypothesize: (1) bacterial suitability, and community structure of organ- community diversity will exhibit a positive isms (Freckman and Virginia 1997, Lee et al. relationship with resource availability (organic 2012). Given the universal constraints to biolog- carbon and/or water) and a negative association ical diversity and activity which arise from both with geochemical severity, while (2) bacterial resource limitations and environmental severity, community structure will be influenced by both these mechanisms likely operate together to resource availability and geochemical severity. In control macro- and microorganismal community addition we quantify a gradient of primary structure alike (Prosser 2007). Indeed, examples production (chlorophyll a) for Antarctic soils of significant productivity/diversity relationships and examine the influence of aboveground have been reported for microorganisms (Horner- productivity on belowground biology and bio- Devine et al. 2003, Smith 2007, Logue et al. 2012). geochemistry. Antarctica’s polar deserts are a model system in which to address questions of controls over microbial biogeography. Resident organisms are sensitive to resource availability, and abiotic factors in general, given the exceptionally low v www.esajournals.org 2 October 2013 v Volume 4(10) v Article 127 GEYER ET AL. Fig. 1. Location of sixteen regional sampling sites in Wright and Taylor Valley of the McMurdo Dry Valleys, Antarctica. See Table 1 for an explanation of site labels. METHODS ents (Barrett et al. 2009) and promoting localized hotspots of primary production (Barrett et al. Site description 2006). The McMurdo Dry Valleys are an ice-free polar The soil food web is simple, microbially- desert in Southern Victoria Land, Antarctica. dominated, and at the base composed of various Aridity (generally less than 10cm of annual prokaryotic, photosynthetic bacteria (Families precipitation), temperature (mean annual be- Nostocaceae, Oscillatoriaceae), eukaryotic algae tween À168CtoÀ218C), and low soil organic carbon availability (0.03% average by weight) (Phyla Chlorophyta, Bacillariophyta), and fewer together constrain the diversity and activity of than 10 species of moss (Family Bryaceae) native biota (Kennedy 1993, Burkins et al. 2000, (Broady 1996, Seppelt and Green 1998) that Hogg et al. 2006). Dry permafrost soils are poorly associate in cryptogamic communities. Several weathered and composed of .90% sand-sized species each of tardigrades, rotifers, and nema- particles with ice cement occurring within 0.5 m todes represent the apex of the soil foodweb of the surface (Ugolini and Bockheim 2008). (Freckman and Virginia 1997, Adams et al. 2006). Salinity and pH are generally
Load more

Recommended publications
  • Biotic Interactions Are an Unexpected Yet Critical Control on the Complexity of an Abiotically Driven Polar Ecosystem
    ARTICLE https://doi.org/10.1038/s42003-018-0274-5 OPEN Biotic interactions are an unexpected yet critical control on the complexity of an abiotically driven polar ecosystem Charles K. Lee et al. # 123456789 0():,; Abiotic and biotic factors control ecosystem biodiversity, but their relative contributions remain unclear. The ultraoligotrophic ecosystem of the Antarctic Dry Valleys, a simple yet highly heterogeneous ecosystem, is a natural laboratory well-suited for resolving the abiotic and biotic controls of community structure. We undertook a multidisciplinary investigation to capture ecologically relevant biotic and abiotic attributes of more than 500 sites in the Dry Valleys, encompassing observed landscape heterogeneities across more than 200 km 2. Using richness of autotrophic and heterotrophic taxa as a proxy for functional complexity, we linked measured variables in a parsimonious yet comprehensive structural equation model that explained signi ficant variations in biological complexity and identi fied landscape-scale and fine-scale abiotic factors as the primary drivers of diversity. However, the inclusion of lin- kages among functional groups was essential for constructing the best- fitting model. Our findings support the notion that biotic interactions make crucial contributions even in an extremely simple ecosystem. Correspondence and requests for materials should be addressed to S.C.C. (email: craig.cary@waikato.ac.nz ). #A full list of authors and their af filiations appears at the end of the paper. COMMUNICATIONS BIOLOGY | (2019) 2:62 | https://doi.org/10.1038/s42003-018-0274-5 | www.nature.com/commsbio 1 ARTICLE COMMUNICATIONS BIOLOGY | https://doi.org/10.1038/s42003-018-0274-5 nderstanding how ecosystems self-organize at landscape soils 20 ,21 ,24 –27 .
    [Show full text]
  • Biotic Interactions Are an Unexpected Yet Critical Control on the Complexity of an Abiotically Driven Polar Ecosystem
    Biotic interactions are an unexpected yet critical control on the complexity of an abiotically driven polar ecosystem Lee, C. K., Laughlin, D. C., Bottos, E. M., Caruso, T., Joy, K., Barrett, J. E., ... Cary, S. C. (2019). Biotic interactions are an unexpected yet critical control on the complexity of an abiotically driven polar ecosystem. Communications Biology, (2), [62]. Published in: Communications Biology Document Version: Publisher's PDF, also known as Version of record Queen's University Belfast - Research Portal: Link to publication record in Queen's University Belfast Research Portal Publisher rights © 2019 The Authors. This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons license, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons license and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this license, visit http://creativecommons.org/ licenses/by/4.0/. General rights Copyright for the publications made accessible via the Queen's University Belfast Research Portal is retained by the author(s) and / or other copyright owners and it is a condition of accessing these publications that users recognise and abide by the legal requirements associated with these rights.
    [Show full text]
  • 18Th EANA Conference European Astrobiology Network Association
    18th EANA Conference European Astrobiology Network Association Abstract book 24-28 September 2018 Freie Universität Berlin, Germany Sponsors: Detectability of biosignatures in martian sedimentary systems A. H. Stevens1, A. McDonald2, and C. S. Cockell1 (1) UK Centre for Astrobiology, University of Edinburgh, UK (adam.stevens@ed.ac.uk) (2) Bioimaging Facility, School of Engineering, University of Edinburgh, UK Presentation: Tuesday 12:45-13:00 Session: Traces of life, biosignatures, life detection Abstract: Some of the most promising potential sampling sites for astrobiology are the numerous sedimentary areas on Mars such as those explored by MSL. As sedimentary systems have a high relative likelihood to have been habitable in the past and are known on Earth to preserve biosignatures well, the remains of martian sedimentary systems are an attractive target for exploration, for example by sample return caching rovers [1]. To learn how best to look for evidence of life in these environments, we must carefully understand their context. While recent measurements have raised the upper limit for organic carbon measured in martian sediments [2], our exploration to date shows no evidence for a terrestrial-like biosphere on Mars. We used an analogue of a martian mudstone (Y-Mars[3]) to investigate how best to look for biosignatures in martian sedimentary environments. The mudstone was inoculated with a relevant microbial community and cultured over several months under martian conditions to select for the most Mars-relevant microbes. We sequenced the microbial community over a number of transfers to try and understand what types microbes might be expected to exist in these environments and assess whether they might leave behind any specific biosignatures.
    [Show full text]
  • ELBA BIOFLUX Extreme Life, Biospeology & Astrobiology International Journal of the Bioflux Society
    ELBA BIOFLUX Extreme Life, Biospeology & Astrobiology International Journal of the Bioflux Society A short review on tardigrades – some lesser known taxa of polyextremophilic invertebrates 1Andrea Gagyi-Palffy, and 2Laurenţiu C. Stoian 1Faculty of Environmental Sciences and Engineering, Babeş-Bolyai University, Cluj- Napoca, Romania; 2Faculty of Geography, Babeş-Bolyai University, Cluj-Napoca, Romania. Corresponding author: A. Gagyi-Palffy, andrea.gagyi@yahoo.com Abstract. Tardigrades are polyextremophilic small organisms capable to survive in a variety of extreme conditions. By reversibly suspending their metabolism (cryptobiosis – tun state) tardigrades can dry or freeze and, thus, survive the extreme conditions like very high or low pressure and temperatures, changes in salinity, lack of oxygen, lack of water, some noxious chemicals, boiling alcohol, even the vacuum of the outer space. Despite their peculiar morphology and amazing diversity of habitats, relatively little is known about these organisms. Tardigrades are considered some lesser known taxa. Studying tardigrades can teach us about the evolution of life on our planet, can help us understand what extremophilic evolution and adaptation means and they can show us what forms of life may develop on other planets. Key Words: tardigrades, extremophiles, extreme environments, adaptation. Rezumat. Tardigradele sunt mici organisme poliextremofile capabile să supraviețuiască într-o varietate de condiţii extreme. Suspendandu-şi reversibil metabolismul (criptobioză) tardigradele pot să se usuce sau să îngheţe şi, astfel, să supravieţuiască unor condiţii extreme precum presiuni şi temperaturi foarte scăzute sau crescute, variaţii de salinitate, lipsă de oxygen, lipsă de apă, unele chimicale toxice, alcool în fierbere, chiar şi vidul spaţiului extraterestru. În ciuda morfologiei lor deosebite şi a diversittii habitatelor lor, se cunosc relativ puţine aspecte se despre aceste organisme.
    [Show full text]
  • Fungal Biodiversity in Extreme Environments and Wood Degradation Potential
    http://waikato.researchgateway.ac.nz/ Research Commons at the University of Waikato Copyright Statement: The digital copy of this thesis is protected by the Copyright Act 1994 (New Zealand). The thesis may be consulted by you, provided you comply with the provisions of the Act and the following conditions of use: Any use you make of these documents or images must be for research or private study purposes only, and you may not make them available to any other person. Authors control the copyright of their thesis. You will recognise the author’s right to be identified as the author of the thesis, and due acknowledgement will be made to the author where appropriate. You will obtain the author’s permission before publishing any material from the thesis. Fungal biodiversity in extreme environments and wood degradation potential A thesis submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Biological Sciences at The University of Waikato by Joel Allan Jurgens 2010 Abstract This doctoral thesis reports results from a multidisciplinary investigation of fungi from extreme locations, focusing on one of the driest and thermally broad regions of the world, the Taklimakan Desert, with comparisons to polar region deserts. Additionally, the capability of select fungal isolates to decay lignocellulosic substrates and produce degradative related enzymes at various temperatures was demonstrated. The Taklimakan Desert is located in the western portion of the People’s Republic of China, a region of extremes dominated by both limited precipitation, less than 25 mm of rain annually and tremendous temperature variation.
    [Show full text]
  • COULD LIFE SURVIVE in ALIEN ENVIRONMENTS? Defining Environments Suitable for Life
    biology | B09 teach with space → COULD LIFE SURVIVE IN ALIEN ENVIRONMENTS? Defining environments suitable for life teacher guide & student worksheets Teacher guide Fast facts page 3 Introduction page 4 Background page 6 Activity: Life in space? page 8 Links page 10 Annex page 11 teach with space – could life survive in alien environments? | B09 www.esa.int/education The ESA Education Office welcomes feedback and comments teachers@esa.int An ESA Education production in collaboration with ESERO Poland Copyright 2019 © European Space Agency → COULD LIFE SURVIVE IN ALIEN ENVIRONMENTS? Could life survive in alien environments? Fast facts Brief description Subject: Biology In this activity students will consider whether Age range: 13-16 years old life found in extreme environments on Earth could survive elsewhere in the Solar System. Type: student activity Students will examine the characteristics Complexity: medium of different places in the Solar System Cost: Low (0 - 10 euros) and then use fact cards of some example Lesson time required: 1 hour extremophiles to hypothesize which they think might be able to survive in the different Location: Classroom extra-terrestrial environments. Includes the use of: Internet, books, library Keywords: Biology, Solar System, Planets, Moons, Extremophiles, Abiotic factors, Search for life Learning objectives • Learn what extremophiles are. • Consider ecological tolerance. • Consider the abiotic factors that affect adaptation and survival of lifeforms. • Learn about the environmental conditions of various Solar System objects. • Understand that changes in environmental conditions have an impact on the evolution of living organisms. teach with space – could life survive in alien environments? | B09 3 → Introduction The more scientists look on Earth, the more life they find.
    [Show full text]
  • Eukaryotic Diversity of Hypolithic Communities in Antarctic Desert Soils
    EUKARYOTIC DIVERSITY OF MIERS VALLEY HYPOLITHS Jarishma Keriuscia Gokul A thesis submitted in partial fulfilment of the requirements for the degree of MAGISTER SCIENTAE (MSc) IN BIOTECHNOLOGY In the Institute for Microbial Biotechnology and Metagenomics Department of Biotechnology University of the Western Cape Bellville Supervisors: Prof. D. A. Cowan Assoc. Prof. I. M. Tuffin Dr. F. Stomeo March 2012 EUKARYOTIC DIVERSITY OF MIERS VALLEY HYPOLITHS Jarishma Keriuscia Gokul KEYWORDS Hypolith Antarctic Dry Valleys Microbial diversity DGGE T-RFLP Culture independent ITS 18S Microalgae DECLARATION I, Jarishma Keriuscia Gokul, declare that the thesis entitled “Eukaryotic Diversity of Miers Valley Hypoliths” is my own work. To the best of my knowledge, all sentences, passages or illustrations quoted in it from other bodies of work have been acknowledged by clear referencing to the author. _______________________ Jarishma Keriuscia Gokul 05 March 2012 i ABSTRACT The extreme conditions of Antarctic desert soils render this environment selective towards a diverse range of psychrotrophic microbial communities. Cracks and fissures in translucent quartz rocks permit an adequate amount of penetrating light, sufficient water and nutrients to support cryptic microbial development. Hypolithons colonizing the ventral surface of these quartz rocks have been classified into three types: cyanobacterial dominated (Type I), moss dominated (Type II) and lichenized (Type III) communities. Eukaryotic microbial communities were reported to represent only a minor fraction of Antarctic communities. In this study, culture independent techniques (DGGE, T-RFLP and clone library construction) were employed to determine the profile of the dominant eukaryotes, fungi and microalgae present in the three different hypolithic communities. The 18S rRNA gene (Euk for eukaryotes), internal transcribed spacer (ITS for fungi) and microalgal specific regions of the 18S rRNA gene, were the phylogenetic markers targeted for PCR amplification from hypolith metagenomic DNA.
    [Show full text]
  • Characterization of Bacterial Communities in Lithobionts and Soil Niches from Victoria Valley, Antarctica Marc W
    FEMS Microbiology Ecology, 92, 2016, fiw051 doi: 10.1093/femsec/fiw051 Advance Access Publication Date: 4 March 2016 Research Article RESEARCH ARTICLE Characterization of bacterial communities in lithobionts and soil niches from Victoria Valley, Antarctica Marc W. Van Goethem1, Thulani P. Makhalanyane1,†, Angel Valverde1, Stephen C. Cary2 and Don A. Cowan1,∗ 1Department of Genetics, Centre for Microbial Ecology and Genomics, University of Pretoria, Lynwood Road, Pretoria 0028, South Africa and 2Department of Biological Sciences, University of Waikato, Private Bag 3105, Hamilton 3120, New Zealand ∗Corresponding author: Department of Genetics, Centre for Microbial Ecology and Genomics, University of Pretoria, Pretoria, 0028, South Africa. Tel: +27-12-420-5873; E-mail: don.cowan@up.ac.za One sentence summary: Characterization of general bacterial and cyanobacterial populations from soil and lithibiontic microbial communities (hypoliths and endoliths) of Victoria Valley, Antarctica. Editor: Dirk Wagner †Thulani P. Makhalanyane, http://orcid.org/0000-0002-8173-1678 ABSTRACT Here we provide the first exploration of microbial diversity from three distinct Victoria Valley edaphic habitats, namely lithobionts (hypoliths, endoliths) and surface soils. Using a combination of terminal restriction fragment length polymorphism (T-RFLP) analysis and 16S rRNA gene amplicon pyrosequencing we assess community structure and diversity patterns, respectively. Our analysis revealed that habitat type (endolithic versus hypolithic versus surface soils) significantly influenced bacterial community composition, even though dominant phyla such as Actinobacteria (41%of total reads) were common to all samples. Consistent with previous surveys in other Dry Valley ecosystems, we found that lithobionts were colonized by a few highly dominant phylotypes (such as Gemmatimonas and Leptolyngbya). Our analyses also show that soil bacteria were more diverse and evenly distributed than initially expected based on previous evidence.
    [Show full text]
  • Life Under Quartz: Hypolithic Mosses in the Mojave Desert
    PLOS ONE RESEARCH ARTICLE Life under quartz: Hypolithic mosses in the Mojave Desert 1 2 Jenna T. B. EkwealorID *, Kirsten M. Fisher 1 Department of Integrative Biology, University of California, Berkeley, California, United States of America, 2 Department of Biological Sciences, California State University, Los Angeles, California, United States of America * jtbe@berkeley.edu a1111111111 a1111111111 a1111111111 Abstract a1111111111 a1111111111 Several species of dryland cyanobacteria are known to occur as hypoliths under semi-trans- lucent rocks. In the Mojave Desert, these organisms find refuge from intense solar radiation under milky quartz where moisture persists for a longer period of time than in adjacent soil surface habitat. Desert mosses, which are extremely desiccation-tolerant, can also occur in OPEN ACCESS these hypolithic spaces, though little is known about this unique moss microhabitat and how Citation: Ekwealor JTB, Fisher KM (2020) Life species composition compares to that of adjacent soil surface communities. To address this under quartz: Hypolithic mosses in the Mojave question, we deployed microclimate dataloggers and collected moss samples from under Desert. PLoS ONE 15(7): e0235928. https://doi. and adjacent to 18 milky quartz rocks (quartz mean center thickness 26 ± 15 mm) in a west- org/10.1371/journal.pone.0235928 ern high elevation Mojave Desert site. Light transmission through Mojave quartz rocks may Editor: Matthew Germino, US Geological Survey, be as low as 1.2%, and data from microclimate loggers deployed for five months support the UNITED STATES hypothesis that quartz provides thermal buffering and higher relative humidity compared to Received: March 28, 2020 the soil surface. Of the 53 samples collected from hypolith and surface microhabitats, 68% Accepted: June 25, 2020 were Syntrichia caninervis, the dominant bryophyte of the Mojave Desert biological soil Published: July 22, 2020 crust.
    [Show full text]
  • Hypolithic Communities: Important Nitrogen Sources in Antarctic Desert
    Environmental Microbiology Reports (2011) 3(5), 581–586 doi:10.1111/j.1758-2229.2011.00266.x Hypolithic communities: important nitrogen sources in Antarctic desert soilsemi4_266 581..586 D. A. Cowan,1* J. A. Sohm,2 T. P. Makhalanyane,1 light while providing protection from the deleterious D. G. Capone,2 T. G. A. Green,3 S. C. Cary3,4 and effects of extreme desiccation, physical disturbance and I. M. Tuffin1 high UVa/b fluxes (Cockell and Stokes, 2004). 1Institute for Microbial Biotechnology and Hypolithic communities are typically dominated by pho- Metagenomics, University of the Western Cape, Cape toautotrophs including cyanobacteria and green algae Town, South Africa. (Cockell and Stokes, 2004; Wood et al., 2008), but moss- 2Wrigley Institute for Environmental Studies, University dominated hypolithons have recently been identified in of Southern California, Los Angeles, CA, USA. Antarctic desert soils (Cowan et al., 2010). These com- 3Department of Biological Sciences, University of munities are now thought to make an important contribu- Waikato, Hamilton, New Zealand. tion to the carbon input budget in depauperate habitats 4College of Earth and Ocean Science, University of such as polar deserts (Burkins et al., 2001). Delaware, Lewes, DE 19958, USA. However, little is known of the nitrogen budgets in Ant- arctic desert soils. Organic nitrogen inputs may be derived from legacy biomass or from lake-derived cyanobacterial Summary biomass distributed within the Dry Valleys by aeolian Hypolithic microbial communities (i.e. cryptic micro- action (Moorhead et al., 1999). Here we demonstrate, for bial assemblages found on the undersides of translu- the first time, that hypolithic communities both possess cent rocks) are major contributors of carbon input the genetic capacity for N2 fixation and exhibit significant into the oligotrophic hyper-arid desert mineral soils of nitrogenase activity, making them an important, and hith- the Eastern Antarctic Dry Valleys.
    [Show full text]
  • The Role of Photoheterotrophic and Chemoautotrophic
    The role of photoheterotrophic and chemoautotrophic prokaryotes in the microbial food web in terrestrial Antarctica: a cultivation approach combined with functional analysis Guillaume Tahon Promotor Prof. Dr. Anne Willems Dissertation submitted in fulfillment of the requirements for the degree of Doctor (Ph.D.) of Science: Biotechnology (Ghent University) Tahon Guillaume | The role of photoheterotrophic and chemoautotrophic prokaryotes in the microbial food web in terrestrial Antarctica: a cultivation approach combined with functional analysis Copyright © 2017, Tahon Guillaume ISBN-number: 978-94-6197-523-2 All rights are reserved. No part of this thesis protected by this copyright notice may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying, recording or by any information storage or retrieval system without written permission of the author and promotor. Printed by University Press | http://www.universitypress.be Ph.D. thesis, Faculty of Sciences, Ghent University, Ghent, Belgium This Ph.D. work was supported by the Fund for Scientific Research – Flanders (project G.0146.12) Publically defended in Ghent, Belgium, May 5th, 2017 Examination committee Prof. Dr. Savvas Savvides (Chairman) L-Probe: Laboratory for protein Biochemistry and Biomolecular Engineering Faculty of Sciences, Ghent University, Belgium VIB Inflammation Research Center VIB, Ghent, Belgium Prof. Dr. Anne Willems (Promotor) LM-UGent: Laboratory of Microbiology Faculty of Sciences, Ghent University, Belgium Prof. Dr. Elie Verleyen (Secretary) Laboratory of Protistology and Aquatic Ecology Faculty of Sciences, Ghent University, Belgium Em. Prof. Dr. Paul De Vos LM-UGent: Laboratory of Microbiology Faculty of Sciences, Ghent University, Belgium Dr. Natalie Leys SCK·CEN: Environment, Health and Safety Belgian Nuclear Research Centre, Mol, Belgium Dr.
    [Show full text]
  • Evidence for Successional Development in Antarctic Hypolithic Bacterial Communities
    The ISME Journal (2013) 7, 2080–2090 & 2013 International Society for Microbial Ecology All rights reserved 1751-7362/13 www.nature.com/ismej ORIGINAL ARTICLE Evidence for successional development in Antarctic hypolithic bacterial communities Thulani P Makhalanyane1,2, Angel Valverde1,2, Nils-Ka˚re Birkeland3, Stephen C Cary4, I Marla Tuffin1 and Don A Cowan1,2 1Department of Genetics, Centre for Microbial Ecology and Genomics, University of Pretoria, Pretoria, South Africa; 2Institute for Microbial Biotechnology and Metagenomics, University of the Western Cape, Cape Town, South Africa; 3Department of Biology, Centre for Geobiology, University of Bergen, Bergen, Norway and 4Department of Biological Sciences, University of Waikato, Hamilton, New Zealand Hypoliths (cryptic microbial assemblages that develop on the undersides of translucent rocks) are significant contributors to regional C and N budgets in both hot and cold deserts. Previous studies in the Dry Valleys of Eastern Antarctica have reported three morphologically distinct hypolithic community types: cyanobacteria dominated (type I), fungus dominated (type II) and moss dominated (type III). Here we present terminal-restriction fragment length polymorphism analyses to elucidate the bacterial community structure in hypolithons and the surrounding soils. We show clear and robust distinction in bacterial composition between bulk surface soils and hypolithons. Moreover, the bacterial assemblages were similar in types II and III hypolithons and clearly distinct from those found in type I. Through 16S rRNA gene 454 pyrosequencing, we show that Proteobacteria dominated all three types of hypolithic communities. As expected, Cyanobacteria were more abundant in type I hypolithons, whereas Actinobacteria were relatively more abundant in types II and III hypolithons, and were the dominant group in soils.
    [Show full text]