Desulfoglaeba alkanexedens gen. nov., sp nov., an n-alkane-degrading, sulfate-reducing bacterium

Two novel sulfate-reducing bacteria, strains ALDC(T) and Lake, which were able to oxidize n-alkanes, were isolated from a naval oily wastewater-storage facility (VA, USA) and from oilfield production water (OK, USA), respectively. The type strain (ALDC(T)) had a narrow substrate specificity and could grow only with n-alkanes (from C-6 to C-12), pyruvate, butyrate, hexanoic acid and 4-methyloctanoic acid. Cells of strain ALDC(T) stained Gram-negative and were slightly curved, short rods with oval ends (2.5-3.0 x 1.0-1.4 mu m), often occurring in pairs. Cells tended to form aggregates or large clusters and were non-motile and did not form endospores. Optimum growth occurred between 31 and 37 degrees C and at pH 6.5-7.2. NaCl was not required for growth, but salt concentrations up to 55 g l(-1) could be tolerated. The DNA G + C content was 53.6 mol%. Phylogenetic analysis of the 16S rRNA genes revealed that strains ALDC(T) and Lake were closely related, but not identical (99.9% similarity). The two strains were not closely related to other known alkane-degrading, sulfate-reducing bacteria or to other genera of the Deltaproteobacteria. Therefore, it is proposed that strain ALDC(T) (= JCM 13588(T) = ATCC BAA-1302(T)) represents the type strain of a novel species and genus, with the name Desulfoglaeba alkanexedens gen. nov., sp. nov.