Desulfoluna butyratoxydans gen. nov., sp. nov., a novel Gram-negative, butyrate-oxidizing, sulfate-reducing bacterium isolated from an estuarine sediment in Japan.

A strictly anaerobic, mesophilic, sulfate-reducing bacterial strain, designated MSL71T, was isolated from an estuarine sediment from the Sea of Japan bordering the Japanese islands and was characterized phenotypically and phylogenetically. The cells were found to be Gram-negative, motile, non-spore-forming, slightly curved rods. Catalase and oxidase activities were not detected. The optimum NaCl concentration for growth was 2.0 % (w/v), the optimum temperature was 30 degrees C and the optimum pH was 6.3. Strain MSL71T utilized formate, butyrate, pyruvate, lactate, malate, ethanol, propanol, butanol, glycerol and H2 as electron donors for sulfate reduction. The organic electron donors used were incompletely oxidized, mainly to acetate. The strain did not use acetate, propionate, fumarate, succinate, methanol, glycine, alanine, serine, aspartate or glutamate. Sulfite and thiosulfate were used as electron acceptors with lactate as an electron donor, but fumarate was not utilized. Without electron acceptors, pyruvate and malate, but not lactate or fumarate, were fermented. The genomic DNA G+C content was 62.0 mol%. Menaquinone MK-8(H4) was the major respiratory quinone. The major cellular fatty acids were C14 : 0, C16 : 0, C16 : 1 omega 7, C18 : 1 omega 9, C18 : 1 omega 7 and C14 : 0 3-OH. A phylogenetic analysis based on the 16S rRNA gene sequence placed the strain in the class Deltaproteobacteria. The closest recognized relative of strain MSL71T was Desulfofrigus fragile (93.9 % sequence similarity) and the next closest recognized species was Desulfofrigus oceanense (93.5 %). On the basis of the significant differences in the 16S rRNA gene sequence and phenotypic characteristics between strain MSL71T and each of the related species, a novel genus and species, Desulfoluna butyratoxydans gen. nov., sp. nov., are proposed to accommodate strain MSL71T. The type strain is MSL71T (=JCM 14721T=DSM 19427T).