Composition of Polar Lipids of Methanobrevibacter arboriphilicus and Structure Determination of the Signature Phosphoglycolipid of Methanobacteriaceae

Total lipid was extracted effectively by the acidified Blight and Dyer solvent system from Methanobrevibacter arboriphilicus A2 cells. The lipid content was 5.8% of dry cell weight. Cell disruption was required for the maximum yield of lipid from the cells. Eighteen polar lipids were detected and their composition was measured. Phosphoglycolipids from several species of Methanobacteriaceae which had the similar mobilities on thin-layer chromatograms were suggested as the common lipid of the family. The phosphoglycolipid (PGL1, 30%) from M. arboriphilicus was identified as gentiobiosyl caldarchaetidylinositol, which was identical to PGL1 of Methanobacterium thermautotrophicum. This confirmed that the lipid could be designated as the signature lipid of the family. The structure of the other major polar lipids were also identified as follows: gentiobiosyl caldarchaeol (GLla, 9.9%), gentiobiosyl archaeol (GLlb, 12.6%), caldar-chaetidylinositol (PL2a, 10.6%) and archaetidylinositol (PL2b, 3.1%).