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 degreesC 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)).