Characterisation of Archaea in soils by polar lipid analysis

While phospholipid fatty acid (PLFA) profiling is a well-established method used for the determination of bacterial and eukaryotic organisms in soil ecology, phospholipid etherlipid (PLEL) analyses for the characterisation of Archaea is a rather new approach. Analyses of PLEL derived isoprenoid side chains by GC/MS provided a broad picture of the archaeal community in a mixed soil extract, as lipids previously identified in isolates belonging to the kingdoms Eury- and Crenarchaeota were covered. Furthermore, ether-linked isoprenoid hydrocarbons, which have not been detected in archaeal isolates and monomethyl-branched alkanes which have only been found in hyperthermophilic bacteria, were detected in these soil extracts. Monomethyl-branched alkanes were the most dominant ones and accounted for 43.4% of the total identified ether-linked hydrocarbons, followed by straight chain (unbranched) and isoprenoid hydrocarbons, which accounted for 34.6 and 15.5%, respectively.