Desulfotomaculum thermocisternum sp nov, a sulfate reducer isolated from a hot North Sea oil reservoir

The organism described in this paper, strain ST90(T) (T = type strain), is a thermophilic, spore-forming, rod-shaped sulfate reducer that was isolated from North Sea oil reservoir formation water, In cultivation the following substances were used as electron donors and carbon sources: H-2-CO2, lactate, pyruvate, ethanol, propanol, butanol, and C-3 to C-10 and C-14 to C-17 carboxylic acids, Sulfate was used as the electron acceptor in these reactions, Lactate was incompletely oxidized, Sulfite and thiosulfate were also used as electron accepters, In the absence of an electron acceptor, the organism grew syntrophically on propionate together with a hydrogenothrophic methanogen, The optimum conditions for growth on lactate and sulfate were 62 degrees C, pH 6.7, and 50 to 200 mM NaCl, The G+C content was 56 mol%, as determined by high-performance liquid chromatography and 57 mol% as determined by thermal denaturation. Spore formation was observed when the organism was grown on butyrate or propanol as a substrate and at low pH values, On the basis of differences in G+C content and phenotypic and immunological characteristics when the organism was compared with other thermophilic Desulfotomaculum species, we propose that strain ST90(T) is a member of a new species, Desulfotomaculum thermocisternum. D. thermocisteunum can be quickly identified and distinguished from closely related Desulfotomaculum species by immunoblotting.