Desulfovibrio hydrothermalis sp nov., a novel sulfate-reducing bacterium isolated from hydrothermal vents

Mesophilic, hydrogenotrophic, sulfate-reducing bacteria were isolated from a deep-sea hydrothermal chimney sample collected at 13degrees N on the East-Pacific Rise at a depth of 2600 m. Two strains (BL5 and H9) were found to be phylogenetically similar to Desuffovibrio profundus (similarity > 99 %), whereas two other strains (H 1 and AM 13(T)) were found to be phylogenetically distinct (similarity 96-4 %) from Desulfovibrio zosterae, their closest relative. Strain AM13(T) was characterized further. It was a barophilic, Gram-negative, non-sporulating, motile, vibrio-shaped or sigmoid bacterium possessing desulfoviridin. It grew at temperatures ranging from 20 to 40 degreesC, with an optimum at 35 degreesC in the presence of 2-5 % NaCl. The pH range for growth was 6-7-8-2 with an optimum around 7-8. Strain AM13(T) utilized H-2/CO2, lactate, formate, ethanol, choline and glycerol as electron donors. Electron acceptors were sulfate, sulfite and thiosulfate, but not elemental sulfur or nitrate. The G+C content of DNA was 47 mol%. Strain AM13(T) (=DSM 14728(T) = CIP107303(T)) differed from D. zosterae not only phylogenetically, but also genomically (DNA-DNA reassociation value between the two bacteria was 23-8%) and phenotypically. This isolate is therefore proposed as the type strain of a novel species of the genus Desulfovibrio, Desulfovibrio hydrothermalis sp. nov.