Anoxygenic Phototrophic Bacteria of the Meromictic Lake Bol’shie Khruslomeny (Oleniy Island, Kandalaksha Gulf, Murmansk Oblast, Russia)

— The composition and structure of the anoxygenic phototrophic bacterial (APB) community in the water column of meromictic Lake Bol’shie Khruslomeny during winter were investigated. The community developed at the depth of 4.25 m, and its activity in the ice-cover period was very low (6.2 µmol C L –1 day –1 ). The water in the zone of highest development of phototrophic bacteria was of an unusual lemon-yellow color, probably due to the production and accumulation of polysulfides. The near-bottom water was also of lemon-yellow color and was resistant to oxidation by the air oxygen. In the zone of peak APB development the content of BChl d from green-colored green sulfur bacteria was considerably higher than that of BChl e from brown-colored green sulfur bacteria: 77 and 23%, respectively. The cultures of green and purple sulfur bacteria were isolated from lake water, and their physiological and genetic characteristics were determined. Two strains of green sulfur bacteria (brown-colored Br Khr17 and green-colored Gr Khr17) contained gas vacuoles in their cells. Phylogenetically they were most closely related to the green-colored strain Chlorobium phaeovibrioides DSM 265 and were identified as new strains of the species Chlorobium phaeovibrioides .