Desulfosporosinus meridiei sp nov., a spore-forming sulfate-reducing bacterium isolated from gasolene-contaminated groundwater

Eight strains of spore-forming, sulfate-reducing bacteria, isolated from groundwater contaminated with motor fuel [mostly benzene, toluene ethylbenzene and xylene (BTEX) compounds] in sandy soil near Perth, Australia, were closely related to Desulfosporosinus (previously Desulfotomaculum) orientis DSM 765 T (95·3-97·3% 16S rDNA sequence similarity). Whole-cell fatty acids were dominated by even-carbon, straight-chain saturated and mono-unsaturated fatty acids, in particular 16:0, 16:1cis9, 14:0 and 18:1cis11. The strains grew at temperatures between 4 and 42°C and in medium containing up to 4% NaCl. The eight strains clustered into two main groups based on phylogeny, randomly amplified polymorphic DNA (RAPD)-PCR patterns and nutritional characteristics. Representatives of the two groups, strain S5 (group A) and strain S10 T (group B) had 81% DNA-DNA homology with each other and therefore should be accommodated in the same species. Strain S10 T had less than 38% homology with Desulfosporosinus orientis DSM 765 T the most closely phylogenetically related type strain available. The new strains were distinguished from Desulfosporosinus orientis DSM 765 T by different banding patterns in a RAPD-PCR, and phenotypically by their inability to utilize fumarate as a carbon and energy source with sulfate as the electron acceptor and by their lower tolerance to NaCl. The DNA G+C contents were 46·8 and 46·9 mol% for strains S5 and S10 T , respectively (Desulfosporosinus orientis DSM 765 T 45·9 mol%). It is proposed that these new strains be placed in a new species of the genus Desulfosporosinus. The name Desulfosporosinus meridiei is proposed, with strain S10 T as the type strain (= DSM 13257 T = NCIMB 13706 T ).