Viable phototrophic sulfur bacteria from the Black-Sea bottom

Phototrophic sulfur bacteria were isolated from Black-Sea mud at depths of 660 and 2,240 m. The species obtained in pure cultures were identified asChromatium warmingii andThiocapsa roseopersicina. In addition,Chlorobium phaeovibrioides occurred in enrichment cultures. The findings prove that Chromatiaceae and Chlorobiaceae are capable of survival in 2000 m depth, in the dark, in the presence of H₂S and organic materials. There is, however, no evidence for growth or reproduction of these organisms in this environment.