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...

It is generally anticipated that particulate organic carbon (POC) for most part is degraded by attached microorganisms during the descent of “marine snow” aggregates toward the deep sea. There is, however, increasing evidence that fresh aggregates can reach great depth and sustain relatively high biological activity in the deep sea. Using a novel high‐pressure setup, we tested the hypothesis that increasing levels of hydrostat...

Summary The membrane lipids diglycosyl‐glycerol dibiphytanyl glycerol tetraethers ( 2G ‐ GDGTs ) in marine subsurface sediments are believed to originate from uncultivated benthic archaea, yet the production of 2G ‐ GDGTs from subseafloor samples has not been demonstrated in vitro . In order to validate sedimentary biosynthesis of 2G ‐ GDGTs , we performed a stable carbon isotope probing experiment on a subseafloor sample with...

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...

Summary Anoxic sediment from a methane hydrate area (Hydrate Ridge, north‐east Pacific; water depth 780 m) was incubated in a long‐term laboratory experiment with semi‐continuous supply of pressurized [1.4 MPa (14 atm)] methane and sulfate to attempt in vitro propagation of the indigenous consortia of archaea (ANME‐2) and bacteria (DSS, Desulfosarcina/Desulfococcus cluster) to which anaerobic oxidation of methane (AOM) with su...

Summary Paclele Mici is a terrestrial mud volcano field located in the Carpathian Mountains (Romania), where thermal alteration of sedimentary organic compounds leads to methane, higher hydrocarbons and other petroleum compounds that are continuously released into the environment. The hydrocarbons represent potential substrates for microorganisms. We studied lipid biomarkers, stable isotope ratios, the effect of substrate (met...