Desulfotomaculum thermocisternum sp. nov., a Sulfate Reducer Isolated from a Hot North Sea Oil Reservoir

Abstract

The organism described in this paper, strain ST90T (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,-CO,, lactate, pyruvate, ethanol, propanol, butanol, and C, to C,, and C,, to C,, carboxylic acids. Sulfate was used as the electron acceptor in these reactions. Lactate was incompletely oxidized. Sulfite and thiosulfate were also used as electron acceptors. In the absence of an electron acceptor, the organism grew syntrophically on propionate together with a hydrogenothrophic methanogen. The optimum conditions for growth on Iactate and sulfate were 62"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 ST90T is a member of a new species, Desulfotomaculum thermocisternum. D. thermocisternum can be quickly identified and distinguished from closely related Desulfotomaculum species by immunoblotting.The genus Desulfotomaculum comprises a heterogeneous group of gram-positive, spore-forming sulfate reducers that includes both mesophilic and thermophilic species. The following seven thermophilic species have been validly described previously: Desulfotomaculum nigYiJicans, which was isolated from canned food (52) and produced oil field water (1, 30); Desulfotomaculum geothermicum, Desulfotomaculum australicum, and Desulfotomaculum kuznetsovii, which were isolated from geothermal groundwater (13, 26, 29) (D. kuznetsovii has also been isolated from cold marine sediment [ 181); Desulfotomaculum thermoacetoxidans and Desulfotomaculum thermobenzoicum, which were isolated from thermophilic fermentation reactors (28, 48); and Desulfotomaculum thermosapovorans, which was isolated from compost (16). Workers have also described several thermophilic Desulfotomaculum strains whose phylogenetic positions within the genus have not been determined (20,39,47).North Sea oil field reservoirs are hot marine habitats that are 1.2 to 6 km below the seafloor; the pressures in these habitats range from 50 to 80 MPa, and the temperatures range from 60 to 200°C. The concentration of sulfate is usually between 0 and 0.6 mM and varies from one reservoir to another. Aliphatic carboxylic acids are the most abundant organic acids in petroleum reservoirs. In North Sea formation water, acetic acid is found at concentrations up to 20 mM, with decreasing concentrations of higher homologs up to octanoic acid (2, 5). These acids are potential electron donors for sulfate reduction. Formic acid is usually not detected (24). During offshore oil producti...

Effects of the antimicrobial tylosin on the microbial community structure of an anaerobic sequencing batch reactor

“…Propionate uptake has been reported in both Gramnegative (Syntrophobacter and Smithella) and Gram-positive (Desulfotomaculum and Pelotomaculum) organisms (Boone and Bryant, 1980;de Bok et al, 2001;Imachi et al, 2002;Nilsen et al, 1996;Plugge et al, 2002). Because Proteobacteria-related clones from days 743, 841, and 939 were closely related to the genus Syntrophobacter (Figure 4 and Table II) and no clones related to Grampositive propionate utilizers were detected in the clone libraries, propionate uptake in the reactor was attributed to Syntrophobacter.…”

Desulfobacter vibrioformis sp. nov., a Sulfate Reducer from a Water-Oil Separation System

“…However, 16s rDNA sequence analyses are unable to separate closely related species with similarity levels of 97% or higher. Their relationships are best determined by phenetic and genetic similarities (14,27,38). Strain B54T differs phenotypically, serologically, and genetically from the other validly described Desulfobacter species.…”

Phylogenetic Analysis of the Genus Desulfotomaculum: Evidence for the Misclassification of Desulfotomaculum guttoideum and Description of Desulfotomaculum orientis as Desulfosporosinus orientis gen. nov., comb. nov.

“…However, fine details concerning the phylogenetic coherence of this genus and the relatedness of its species have not yet been fully explored. Most previous studies included only a few species, and even the most recently published phylogenetic trees did not include more than eight or nine species (14,18,31). These studies showed that the majority of species cluster together to form a major subline of descent among the several clusters encompassing clostridia and their non-spore-forming and/or coccoid relatives (4).…”