ISOLATION AND CHARACTERIZATION OF A NOVEL SULFATE-REDUCING BACTERIUM OF THE DESULFOVIBRIO GENUS

A novel sulphate-reducing bacterium (Ind 1) was isolated from a biofil m removed from a severely corroded carbon steel structure in a marine environment. Light microscopy observations revealed that cells were Gr amnegative, rod shaped and very motile. Partial 16S rRNA gene sequenci ng and analysis of the fatty acid profile demonstrated a strong simila rity between the new species and members from the Desulfovibrio genus. This was confirmed by the results obtained following purification and characterisation of the key proteins involved in the sulphate-reducti on pathway. Several metal-containing proteins, such as two periplasmic proteins: hydrogenase and cytochrome c(3), and two cytoplasmic protei ns: ferredoxin and sulphite reductase, were isolated and purified. The latter proved to be of the desulfoviridin type which is typical of th e Desulfovibrio genus. The study of the remaining proteins revealed a high degree of similarity with the homologous proteins isolated from D esulfovibrio gigas. However, the position of the strain within the phy logenetic tree clearly indicates that the bacterium is closely related to Desulfovibrio gabonensis, and these three strains form a separate cluster in the delta subdivision of the Proteobacteria. On the basis o f the results obtained, it is suggested that Ind 1 belongs to a new sp ecies of the genus Desulfovibrio, and the name Desulfovibrio indonensi s is proposed. (C) 1998 Academic Press.