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| Titel |
Methane-related changes in prokaryotes along geochemical profiles in sediments of Lake Kinneret (Israel) |
| VerfasserIn |
I. Bar-Or, E. Ben-Dov, A. Kushmaro, W. Eckert, O. Sivan |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1726-4170
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| Digitales Dokument |
URL |
| Erschienen |
In: Biogeosciences ; 12, no. 10 ; Nr. 12, no. 10 (2015-05-19), S.2847-2860 |
| Datensatznummer |
250117934
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| Publikation (Nr.) |
 copernicus.org/bg-12-2847-2015.pdf |
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| Zusammenfassung |
| Microbial methane oxidation is the primary control on the
emission of the greenhouse gas methane into the atmosphere. In terrestrial
environments, aerobic methanotrophic bacteria are largely responsible for
this process. In marine sediments, a coupling of anaerobic oxidation of
methane (AOM) with sulfate reduction, often carried out by a consortium of
anaerobic methanotrophic archaea (ANME) and sulfate-reducing bacteria,
consumes almost all methane produced within those sediments. Motivated by
recent evidence for AOM with iron(III) in Lake Kinneret sediments, the goal
of the present study was to link the geochemical gradients in the lake
porewater to the microbial community structure. Screening of archaeal 16S
rRNA gene sequences revealed a shift from hydrogenotrophic to acetoclastic
methanogens with depth. The observed changes in microbial community
structure suggest possible direct and indirect mechanisms for the AOM
coupled to iron reduction in deep sediments. The percentage of members of the Nitrospirales order increased
with depth, suggesting their involvement in iron reduction together with
Geobacter genus and "reverse methanogenesis". An indirect mechanism through sulfate
and ANME seems less probable due to the absence of ANME sequences. This is
despite the abundant sequences related to sulfate-reducing bacteria
(Deltaproteobacteria) together with the occurrence of dsrA
in the deep sediment that could
indicate the production of sulfate (disproportionation) from S0 for
sulfate-driven AOM. The presence of the functional gene pmoA in the deep anoxic
sediment together with sequences related to Methylococcales suggests the existence of a
second unexpected indirect pathway – aerobic methane oxidation pathway in an
anaerobic environment. |
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