CHARACTERISTICS OF THE PHOTOSYNTHETIC APPARATUS OF THE PURPLE BACTERIUM THIOCAPSA SP. BM3 CONTAINING OKENONE AS A MAJOR CAROTENOID

Photosynthetic apparatus of the purple bacterium Thiocapsa sp. BM3 was studied. This strain was isolated from an algobacterial mat in a lago on of the White Sea and, according to data from DNA-DNA hybridization, represents a new species of the genus Thiocapsa. An LH1-RC ensemble, LH2 light-harvesting complex, and a fraction of free pigments were iso lated from the membranes of this bacterium. Investigation of carotenoi ds showed that the LH1-RC ensemble contained okenone and spirilloxanth in, whereas the LH2 complex contained only okenone. The fraction of fr ee pigments contained carotenoids; depending on the type of detergent used, it could also contain bacteriochlorophyll. In the latter case, t he absorption spectrum of the fraction was similar to that of the ''ca rotenoid-containing B820 subcomplex'' isolated from Chromatium purpura tum. The possible involvement of carotenoids in the assembly of photos ynthetic complexes is discussed.