The ecological dichotomy of ammonia-oxidizing archaea and ba

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TitleThe ecological dichotomy of ammonia-oxidizing archaea and bacteria in the hyper-arid soils of the Antarctic Dry ValleysAbstractThe McMurdo Dry Valleys of Antarctica are considered to be one of the most physically and chemically extreme terrestrial environments on the Earth. However, little is known about the organisms involved in nitrogen transformations in these environments. In this study, we investigated the diversity and abundance of ammonia7 oxidizing archaea (AOA) and bacteria (AOB) in four McMurdo Dry Valleys with highly variable soil geochemical properties and climatic conditions: Miers Valley, Upper Wright Valley, Beacon Valley and Battleship Promontory. The bacterial communities of these four Dry Valleys have been examined previously, and the results suggested that the extremely localized bacterial diversities are likely driven by the disparate physicochemical conditions associated with these locations. Here we showed that AOB and AOA amoA gene diversity was generally low; only four AOA and three AOB operational taxonomic units (OTUs) were identified from a total of 420 AOA and AOB amoA clones. Quantitative PCR analysis of amoA genes revealed clear differences in the relative abundances of AOA and AOB amoA genes among samples from the four Dry Valleys. Although AOB amoA gene dominated the ammonia-oxidizing community in soils from Miers Valley and Battleship Promontory, AOA amoA gene were more abundant in samples from Upper Wright and Beacon Valleys, where the environmental conditions are considerably harsher (e.g., extremely low soil C/N ratios and much higher soil electrical conductivity). Correlations between environmental variables and amoA genes copy numbers, as examined by redundancy analysis (RDA), revealed that higher AOA/AOB ratios were closely related to soils with high salts and Cu contents and low pH. Our findings hint at a dichotomized distribution of AOA and AOB within the Dry Valleys, potentially driven by environmental constraints. Copyright 2014 Magalhaes, Machado, Frank-Fahle, Lee and Cary.AcknowledgementsWe are sincerely grateful to Antarctica New Zealand for providing logistics support. We thank L. Torgo for their assistance in statistical analyses, F. Castro in designing the new primers, and A. Bordalo and A. P. Mucha for the loan of the real-time PCR system (CFX96, BioRad) and laboratory space for sampling processing. We also thank W. J. Wiebe for the extremely helpful comments on the manuscript. This study was conducted as part of the New Zealand Latitudinal Gradient Project (LGP) and the New Zealand Terrestrial Antarctic Biocomplexity Survey (nzTABS), a New Zealand International Polar Year program supported through a grant from the New Zealand Foundation for Research, Science and Technology to S. Craig Cary (UOWX0710). This study was funded by the Portuguese Science and Technology Foundation (FCT) through a researcher starting grant to Catarina M. MagalhÃ£es (FCT 2012) and by FCT and FEDER throughout a grant to Catarina M. MagalhÃ£es (PTDC/MAR/112723/2009--FCOMP-01-0124-FEDER-015422), and partially supported by the European Regional Development Fund (ERDF) through the COMPETE--Operational Competitiveness Program and national funds through FCT--Foundation for Science and Technology, under the project "PEst-C/MAR/LA0015/2011". This study was also funded by PROPOLAR through a grant to Catarina M. Magalhaes. CKL was supported by FRST Postdoctoral Research Fellowship (UOWX0715), the New Zealand Marsden Fund (UOW1003), and the New Zealand Antarctic Research Institute (NZARI2013-7).

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1st AuthorMagalhaes, C.AuthorMagalhaes, C.Machado, A.Frank-Fahle, B.Lee, C.Cary, C.Year2014JournalFrontiers in MicrobiologyVolume5NumberSEPDOI10.3389/fmicb.2014.00515URLhttps://www.scopus.com/inward/recor.....85502e9a5aa716e73774bd6ebKeywordsbromidemercaptoethanolpovidone, amino acid sequenceammonia oxidizing archaeonAntarcticaArticlebacteriumcomparative molecular field analysisDNA extractionecologyelectric conductivitynitrogen fixationnonhumanphylogenypolymerase chain reactionreal time polymerase chain reactionrestriction fragment length polymorphismsoil analysis, rank5Author KeywordsAmmonia oxidizersAntarcticaAOAAOBArchaeaBacteriaDry valleys

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TypeArticleCitationMagalhaes, C., Machado, A., Frank-Fahle, B., Lee, C. and Cary, C. (2014). The ecological dichotomy of ammonia-oxidizing archaea and bacteria in the hyper-arid soils of the Antarctic Dry Valleys. Frontiers in Microbiology, 5 IdentifierMagalhaes2014Relevancerank5

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Cary, C.