Methane-related changes in prokaryotes along geochemical profiles in sediments of Lake Kinneret (Israel)

I. Bar-Or, E. Ben-Dov, A. Kushmaro, W. Eckert, O. Sivan

Research output: Contribution to journalArticlepeer-review

20 Scopus citations

Abstract

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.

Original languageEnglish
Pages (from-to)2847-2860
Number of pages14
JournalBiogeosciences
Volume12
Issue number10
DOIs
StatePublished - 19 May 2015

ASJC Scopus subject areas

  • Ecology, Evolution, Behavior and Systematics
  • Earth-Surface Processes

Fingerprint

Dive into the research topics of 'Methane-related changes in prokaryotes along geochemical profiles in sediments of Lake Kinneret (Israel)'. Together they form a unique fingerprint.

Cite this