In cold seeps, anaerobic methanotrophic archaea (ANME) and sulphate‐reducing bacteria (SRB) oxidise methane to inorganic carbon (IC) coupled to sulphate reduction. While catabolic pathways are well resolved, carbon flow into biomass as well as the functional roles of lipid biomarkers remain unclear. We conducted lipid stable isotope probing (lipid‐SIP) experiments with Astoria Canyon sediments dominated by ANME‐2/SRB consortia...

Summary Methyl‐coenzyme M reductase (MCR) has been originally identified to catalyse the final step of the methanogenesis pathway. About 20 years ago an aerobic me thane‐oxidizing archaea (ANME) were discovered that use MCR enzymes to activate methane. ANME thrive at the thermodynamic limit of life, are slow‐growing, and in most cases form syntrophic consortia with sulfate‐reducing bacteria. Recently, archaea that have the abi...

Summary The sulfate‐dependent, anaerobic oxidation of methane (AOM) is an important sink for methane in marine environments. It is carried out between anaerobic methanotrophic archaea (ANME) and sulfate‐reducing bacteria (SRB) living in syntrophic partnership. In this study, we compared the genomes, gene expression patterns and ultrastructures of three phylogenetically different microbial consortia found in hydrocarbon‐rich en...

Summary The anaerobic oxidation of methane (AOM) is mediated by consortia of anaerobic methane‐oxidizing archaea (ANME) and their specific partner bacteria. In thermophilic AOM consortia enriched from Guaymas Basin, members of the ANME‐1 clade are associated with bacteria of the HotSeep‐1 cluster, which likely perform direct electron exchange via nanowires. The partner bacterium was enriched with hydrogen as sole electron dono...

Summary Sub‐seafloor sediments are populated by large numbers of microbial cells but not much is known about their metabolic activities, growth rates and carbon assimilation pathways. Here we introduce a new method enabling the sensitive detection of microbial lipid production and the distinction of auto‐ and heterotrophic carbon assimilation. Application of this approach to anoxic sediments from a Swedish fjord allowed to com...

Summary The anaerobic oxidation of methane (AOM) is a major sink for methane on Earth and is performed by consortia of methanotrophic archaea (ANME) and sulfate‐reducing bacteria (SRB). Here we present a comparative study using in vitro stable isotope probing to examine methane and carbon dioxide assimilation into microbial biomass. Three sediment types comprising different methane‐oxidizing communities (ANME‐1 and ‐2 mixture...