TAXONOMIC SIGNIFICANCE OF THE DISTRIBUTION OF COMPONENT PARTS OF POLAR ETHER LIPIDS IN METHANOGENS

The ether core lipids, phospholipid-polar head groups and glycolipid-sugar moieties (component parts of polar lipids) from 18 species of methanogens, belonging to 5 families, were analysed qualitatively at the total lipid level, without separation of lipids after extraction, and the results were cumulated to the data published previously from 13 other species. Archaeol, caldarchaeol, macrocyclic archaeol, and two kinds of hydroxyarchaeol were found as core lipids; myo-inositol, ethanolamine, serine, aminopentanetetrols, glycerol, and N-acetylglucosamine were identified as phospholipid-polar head groups; and glucose, galactose, and mannose as glycolipid-sugars in methanogens as a whole. The distribution of these component parts, regardless their arrangement in the lipid molecules, was characteristic of methanogen taxonomic groups at a family or genus level, and, therefore, coincided with the classification based on the 16S rRNA analysis. This shows that lipid component parts could become a new chemotaxonomic marker, which utilises more lipid-structure-oriented information than a thin-layer chromatographic pattern. A determinative key of methanogens, only based on lipid component analysis, is proposed.