LIPIDS OF THERMOCOCCUS-HYDROTHERMALIS, AN ARCHAEA ISOLATED FROM A DEEP-SEA HYDROTHERMAL VENT

The membrane lipids of a deep-sea hydrothermal vent archaea, Thermococ cus hydrothermalis, were isolated, purified, and structurally characte rized. On the basis of acid methanolysis and spectroscopic studies, th e polar lipids, amounting to 4.5% (w/w) of the dry cells, comprised di phytanyl glycerol diethers and dibiphytanyldiglycerol tetraethers, in a 45:55 ratio. No cyclopentane ring was present in the tetraethers. Fr om the neutral lipids, accounting for 0.4% (w/w) of the dry cells, bes ides low amounts of di- and tetraethers occurring in a free form, four acyclic tetraterpenoid hydrocarbons, di- and triunsaturated were iden tified. All were structurally related to lycopane. The presence of the se hydrocarbons provides some evidence that lycopane, widely distribut ed in oceans, could be derived, at least partially, from the hydrocarb ons synthesized by some thermophilic Archaea. Finally, analysis of the uninoculated culture medium indicates that fatty acid derivatives and some steroid and triterpenoid compounds identified in the lipidic ext ract of the archaea originated from the culture medium.