Phospholipid etherlipid and phospholipid fatty acid fingerprints in selected euryarchaeotal monocultures for taxonomic profiling.

Phospholipid etherlipid (PLEL) derived isoprenoids and phospholipid fatty acids (PLFA) were determined in eight Euryarchaeotal monocultures for taxonomic profiling. For the first time significant amounts of fatty acids in the PLFA of Euryarchaeota were determined. The PLFA proportion varied between 11.3 and 35.5% of the total phospholipid side chains except in Methanothermus fervidus where PLFA accounted for 89.0% of the total phospholipid side chains. Fractionation of fatty acids prior to gas chromatography mass spectrometry analysis revealed that non-ester-linked fatty acids dominated which accounted for 85.5-95.2% of total PLFA in all investigated archaeal strains. PLEL concentration and composition was estimated in accordance with previous studies with two exceptions. In the polar (phospho)lipid fraction of Methanopyrus kandleri side chains possibly derived from hydroxyarchaeol as well as acyclic and cyclic caldarchaeol were identified. In phospholipid extracts of Methanothermus fervidus the 'H-formed' caldarchaeol could not be detected. Overall, PLEL derived isoprenoids as well as PLFA enabled taxonomic differentiation of the selected microorganisms into phylogenetically related groups.