Microbial communities performing anaerobic oxidation of methane: diversity of lipid signatures and habitats

The goal of this thesis was to study the microbial communities performing the anaerobic oxidation of methane, using intact polar lipid (IPL) and apolar lipid composition, in relation to the environment. The three types of anaerobic methanotrophic microbial consortia (ANME-1/DSS, -2/DSS and -3/DBB) formed by archaea (ANMEs) and their sulfate reducing bacterial partners (SRB) could be clearly distinguished by IPL composition but not by apolar lipids. ANME-1/DSS contained glyceroldialkylglyceroltetraethers-, whereas ANME-2/DSS and ANME-3/DBB presented archaeol-based IPLs. Both IPLs types presented glycosidic, glycosidic/phospho or only phospho headgroups, ANME-3 having only the latter. From all three consortia, lower contribution of IPLs from SRB was observed in ANME-1/DSS. Based on the relation between IPL distribution and several environmental factors, ANME-1/DSS dominates habitats with higher temperature and lower underlying oxygen content compared to the habitats where the other two consortia dominate. Moreover, ANME-2/DSS is selected in habitats with efficient supply of methane and sulfate.