ISOPRANYLGLYCEROL DIETHERS IN NONALKALINE EVAPORITIC ENVIRONMENTS

Gas chromatographic-mass spectrometric analyses of Tertiary and recent halite samples using high-temperature gas chromatographic columns hav e shown that O-phytanyl-O-sesterterpanylglycerol and bis-O-phytanylgly cerol are common constituents in halites deposited in non-alkaline sys tems. These isopranylglycerol diether distributions are in contrast wi th those found in carbonates and most sulphates deposited in solar sal terns or in sediments of mesohaline lagoons, which contain only the C2 0-C20 homolog. The investigation of the distributions of these compoun ds in thirteen species of non-alkaliphilic halobacteria has revealed t hat bis-O-phytanylglycerol occurs as the single homolog in most cases. namely Halobacterium. Haloferax, and Haloarcula spp., but O-phytanyl- O-sesterterpanylglycerol has been found in one Halococcus species. The presence of this C20-C25 diether in this genus of extremely halophili c archaebacterial cocci expands the limited number of organisms known previously as potential precursors of this isopranylglycerol, alkaliph ilic halobacteria, and Methanosarcina spp. and indicates that its wide spread occurrence in recent and Tertiary halites is related with contr ibutions from non-alkaliphilic halobacteria.