Desulfovibrio africanus subsp. uniflagellum subsp. nov., a sulfate-reducing bacterium from a uranium-contaminated subsurface aquifer

The bacterial strain SR-1(T) was isolated from subsurface sediments of a uranium-contaminated site in Shiprock, New Mexico, USA. Cells are vibrioid and motile by means of a single polar flagellum. Strain SR-1(T) grows on sulfate, oxidizing formate, lactate and H2, but not malate, and ferments pyruvate. The DNA sequences of the 16S rRNA gene and the 16S-23S internal transcribed spacer of strain SR-1(T) showed 99.9 and 99.4 % similarity, respectively, to those of the type strain Desulfovibrio africanus DSM 2603(T). The DNA sequence of the ITS region is 300 bases in length and contains two tRNA genes (tRNA(Ile), tRNA(Ala)). The partial DNA sequence of the dsrAB gene showed 94.6 % amino acid sequence similarity to that of D. africanus. The DNA G+C content of strain SR-1(T) was 62.4 mol% and it showed 72 % DNA-DNA similarity to D. africanus. DNA typing methods that target gene clusters and whole genomes revealed characteristic genomic fingerprints for strain SR-1(T). A small plasmid was detected by gel electrophoresis. On the basis of distinct phenotypic and genotypic characteristics, strain SR-1(T) represents a novel subspecies of D. africanus, for which the name Desulfovibrio africanus subsp. uniflagellum subsp. nov. is proposed. The type strain is SR-1(T) (=JCM 15510(T) =LS KCTC 5649(T)).