BACTERIAL CAROTENOIDS .55. C-50-CAROTENOIDS .25. REVISED STRUCTURES OF CAROTENOIDS ASSOCIATED WITH MEMBRANES IN PSYCHROTROPHIC MICROCOCCUS-ROSEUS

The carotenoid composition of a psychrotrophic bacterium Micrococcus r oseus strain MTCC 678 has been re-examined qualitatively and quantitat ively by chromatographic (TLC, HPLC) and spectroscopic (VIS, MS, H-1 N MR and CD) methods, partly in direct comparison with authentic caroten oids. The carotenoid content of 0.13% of the dry weight consisted of ( 2S,2'S)-bacterioruberin (68% of total), bacterioruberin monoglycoside (21%), monoanhydrobacterioruberin (6%), an unidentified polar tridecae ne carotenoid (3%), haloxanthin (2%) and beta,beta-carotene (0.4%): a carotenoid complement associated with that of halophilic bacteria. Rap id analysis demonstrated that bacterioruberin occurred as the all-E is omer (75% of total), together with the 5Z-(5%), 9Z-(5%) and 13Z-(15%) geometrical isomers. The established interaction of the major caroteno id with membrane vesicles, compatible with cold adaptation, is rationa lized. (C) 1997 Elsevier Science Ltd.