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 roseus strain MTCC 678 has been re-examined qualitatively and quantitatively by chromatographic (TLC, HPLC) and spectroscopic (VIS, MS, H-1 NMR and CD) methods, partly in direct comparison with authentic carotenoids. 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 tridecaene carotenoid (3%), haloxanthin (2%) and beta,beta-carotene (0.4%): a carotenoid complement associated with that of halophilic bacteria. Rapid analysis demonstrated that bacterioruberin occurred as the all-E isomer (75% of total), together with the 5Z-(5%), 9Z-(5%) and 13Z-(15%) geometrical isomers. The established interaction of the major carotenoid with membrane vesicles, compatible with cold adaptation, is rationalized. (C) 1997 Elsevier Science Ltd.