The anaerobic oxidation of methane (AOM) with sulfate as terminal electron acceptor is mediated by consortia of methanotrophic archaea (ANME) and sulfate-reducing bacteria (SRB). In sediment samples from Hydrate Ridge, the Isis Mud Volcano and the Gulf of Mexico, DSS cells accounted for 3-6% of all DAPI-stained single cells. Out of these, 8-17% were labelled with probe SEEP1a-1441. This translated into relative abundances of single SEEP-SRB1a cells of 0.3% to 0.7%. Contrastingly, in a sediment sample from the Gullfaks oil field, DSS cells accounted for 18% and SEEP-SRB1a for 9% of all single cells. This sediment sample also featured an unusually high abundance of single ANME-2 cells and only very few ANME-2/DSS aggregates in comparison with other AOM habitats. Considering also the nature of the sample, it is likely that the high number of single ANME-2 and SEEP-SRB1a cells were an artifact of sample preparation. Here, harsher sonication was required to remove the microorganisms from coarse sand prior to CARD-FISH analysis.

Total and absolute cell numbers based on Knittel et al. (2005; doi:10.1128/AEM.71.1.467-479.2005) and Wegener et al. (2008; doi:10.5194/bg-5-1127-2008).

Supplement to: Schreiber, L; Holler, L; Knittel, Katrin; Meyerdierks, Anke; Amann, Rudolf (2010): Identification of the dominant sulfate-reducing bacterial partner of anaerobic methanotrophs of the ANME-2 clade. Environmental Microbiology, 12(8), 2327-2340