Affiliation:
1. Monterey Bay Aquarium Research Institute, Moss Landing, California 95039,1 and
2. Department of Geology and Geophysics, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts 025432
Abstract
ABSTRACT
The oxidation of methane in anoxic marine sediments is thought to be mediated by a consortium of methane-consuming archaea and sulfate-reducing bacteria. In this study, we compared results of rRNA gene (rDNA) surveys and lipid analyses of archaea and bacteria associated with methane seep sediments from several different sites on the Californian continental margin. Two distinct archaeal lineages (ANME-1 and ANME-2), peripherally related to the order
Methanosarcinales
, were consistently associated with methane seep marine sediments. The same sediments contained abundant
13
C-depleted archaeal lipids, indicating that one or both of these archaeal groups are members of anaerobic methane-oxidizing consortia.
13
C-depleted lipids and the signature 16S rDNAs for these archaeal groups were absent in nearby control sediments. Concurrent surveys of bacterial rDNAs revealed a predominance of δ-proteobacteria, in particular, close relatives of
Desulfosarcina variabilis
. Biomarker analyses of the same sediments showed bacterial fatty acids with strong
13
C depletion that are likely products of these sulfate-reducing bacteria. Consistent with these observations, whole-cell fluorescent in situ hybridization revealed aggregations of ANME-2 archaea and sulfate-reducing
Desulfosarcina
and
Desulfococcus
species. Additionally, the presence of abundant
13
C-depleted ether lipids, presumed to be of bacterial origin but unrelated to ether lipids of members of the order
Desulfosarcinales
, suggests the participation of additional bacterial groups in the methane-oxidizing process. Although the
Desulfosarcinales
and ANME-2 consortia appear to participate in the anaerobic oxidation of methane in marine sediments, our data suggest that other bacteria and archaea are also involved in methane oxidation in these environments.
Publisher
American Society for Microbiology
Subject
Ecology,Applied Microbiology and Biotechnology,Food Science,Biotechnology
Cited by
578 articles.
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