Desulfovibrio capillatus sp. nov., a novel sulfate-reducing bacterium isolated from an oil field separator located in the Gulf of Mexico

A new spirilloid sulfate-reducing bacterium designated strain MET2^T (T=type strain), was isolated from a Mexican oil field separator. Electron microscopy revealed a Gram-negative cell wall consisting of a 150nm thick undulating outer membrane. Strain MET2^T appeared singly or in long chains and was actively motile with a corkscrew-like motion. The isolate grew optimally at 40°C, pH 7.4 and 3% NaCl in a medium containing lactate, thiosulfate and yeast extract. Sulfate, sulfite, thiosulfate, and elemental sulfur served as electron acceptors but not nitrate or fumarate. Lactate, pyruvate and H₂ (with acetate as carbon source) were used as electron donors. Pyruvate was fermented. Desulfoviridin and cyt c were present. The G+C content of the DNA was 58.7mol%. Phylogenetic analysis based on 16S rDNA sequencing showed that strain MET2^T was a member of the genus Desulfovibrio with "D. gracilis" and D. longus being its closest relatives (similarities of 98.3% and 97.1%, respectively). However, DNA-DNA hybridization studies indicated poor homologies (values <70%) with both species. On the basis of genotypic, phenotypic, and phylogenetic characteristics, strain MET2^T (=DSM14982^T=CIP107483^T) is proposed as the type strain of a new species, Desulfovibrio capillatus sp. nov. GenBank accession number for the 16S rDNA sequence for MET2^T is AY176773.