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Abundance, Distribution, and Activity of Fe(II)-Oxidizing and Fe(III)-Reducing Microorganisms in Hypersaline Sediments of Lake Kasin, Southern Russia
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Titel: |
Abundance, Distribution, and Activity of Fe(II)-Oxidizing and Fe(III)-Reducing Microorganisms in Hypersaline Sediments of Lake Kasin, Southern Russia |
In: | Applied and Environmental Microbiology, 78, 2012, 12, S. 4386-4399 |
veröffentlicht: |
American Society for Microbiology
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Umfang: | 4386-4399 |
ISSN: |
0099-2240 1098-5336 |
DOI: | 10.1128/aem.07637-11 |
Zusammenfassung: | <jats:title>ABSTRACT</jats:title> <jats:p> The extreme osmotic conditions prevailing in hypersaline environments result in decreasing metabolic diversity with increasing salinity. Various microbial metabolisms have been shown to occur even at high salinity, including photosynthesis as well as sulfate and nitrate reduction. However, information about anaerobic microbial iron metabolism in hypersaline environments is scarce. We studied the phylogenetic diversity, distribution, and metabolic activity of iron(II)-oxidizing and iron(III)-reducing <jats:named-content content-type="genus-species">Bacteria</jats:named-content> and <jats:named-content content-type="genus-species">Archaea</jats:named-content> in pH-neutral, iron-rich salt lake sediments (Lake Kasin, southern Russia; salinity, 348.6 g liter <jats:sup>−1</jats:sup> ) using a combination of culture-dependent and -independent techniques. 16S rRNA gene clone libraries for <jats:named-content content-type="genus-species">Bacteria</jats:named-content> and <jats:named-content content-type="genus-species">Archaea</jats:named-content> revealed a microbial community composition typical for hypersaline sediments. Most-probable-number counts confirmed the presence of 4.26 × 10 <jats:sup>2</jats:sup> to 8.32 × 10 <jats:sup>3</jats:sup> iron(II)-oxidizing <jats:named-content content-type="genus-species">Bacteria</jats:named-content> and 4.16 × 10 <jats:sup>2</jats:sup> to 2.13 × 10 <jats:sup>3</jats:sup> iron(III)-reducing microorganisms per gram dry sediment. Microbial iron(III) reduction was detected in the presence of 5 M NaCl, extending the natural habitat boundaries for this important microbial process. Quantitative real-time PCR showed that 16S rRNA gene copy numbers of total <jats:named-content content-type="genus-species">Bacteria</jats:named-content> , total <jats:named-content content-type="genus-species">Archaea</jats:named-content> , and species dominating the iron(III)-reducing enrichment cultures (relatives of <jats:named-content content-type="genus-species">Halobaculum gomorrense</jats:named-content> , <jats:named-content content-type="genus-species">Desulfosporosinus lacus</jats:named-content> , and members of the <jats:named-content content-type="genus-species">Bacilli</jats:named-content> ) were highest in an iron oxide-rich sediment layer. Combined with the presented geochemical and mineralogical data, our findings suggest the presence of an active microbial iron cycle at salt concentrations close to the solubility limit of NaCl. </jats:p> |
Format: | E-Article |
Quelle: | American Society for Microbiology (CrossRef) |
Sprache: | Englisch |