BACTERIAL CAROTENOIDS-53, C-50-CAROTENOIDS-23 - CAROTENOIDS OF HALOFERAX-VOLCANII VERSUS OTHER HALOPHILIC BACTERIA

The carotenoid composition of the halophilic bacterium Haloferax volca nii has been studied qualitatively and quantitatively by chromatograph ic (CC, TLC, HPLC, several systems), spectroscopic (VIS, MS, 1D and 2D H-1 NMR, Co) and chemical (silylation and methylation) methods. Halof erax volcanii contained 0.04% carotenoids of the dry wt., consisting o f the C-50-carotenoids (2S, 2S)-bacterioruberin (82% of total caroteno id), monoanydrobacterioruberin (7%), (2S, 2'S)-bisanhydrobacterioruber in (3%), 3',4'-dihydromonoanhydrobacterioruberin (2%) and two undecaen e C50H74O4 carotenoids (each 2%), the C-45-carotenoid (2S)-2-isopenten yl-3,4-dehydrorhodopin (1%) and lycopene (C-40, 0.3%) The C-50-caroten oids were isolated as complex mixtures of identified geometrical isome rs, separated by HPLC. Geometrical isomers were identified by VIS abso rption and H-1 NMR data. The natural occurrence of Z isomers is inferr ed. Chemosystematic implications are discussed with reference to carot enoid analyses of other halophilic bacteria. Functional aspects includ ing membrane reinforcement are briefly considered.