DESULFOBACTER VIBRIOFORMIS SP. NOV., A SULFATE REDUCER FROM A WATER-OIL SEPARATION SYSTEM

A mesophilic, gram-negative, vibrio-shaped, marine, acetate-oxidizing sulfate reducer (strain B54) was isolated from a water-oil separation system on a North Sea oil platform. The optimum conditions for growth mere 33 degrees C, pH 6.8 to 7.0, and concentrations of NaCl and MgCl2 . 6H(2)O of at least 1 and 0.3%, respectively. Of various organic aci ds tested, only acetate was used as an electron and carbon source. The presence of 2-oxoglutarate:dye oxidoreductase suggests acetate oxidat ion via an operative citric arid cycle. Even though growth of most Des ulfobacter strains (including strain B54) did not occur on hydrogen, h ydrogenase was detected at low activity. The growth fields were 4.6, 1 3.1, and 9.6 g of (dry weight) cells per mol of acetate oxidized with sulfate, sulfite, and thiosulfate, respectively, as electron accepters . Strain B54 was able to fix dinitrogen. Desulforubidin and cytochrome s of the c and b types were present. The G+C content of the DNA was 47 mol%. Strain B54 is most closely related to Desulfobacter latus, with a 16S rDNA sequence similarity of 98.1%. The DNA-DNA relatedness betw een them was 40.5%. On the basis of differences in genotypic, phenotyp ic, and immunological characteristics, we propose that strain B54 is a member of a new species, D. vibrioformis. It can be easily identified and distinguished from other Desulfobacter species by its large, vibr io-shaped cells.