ISOLATION AND CHARACTERIZATION OF A THERMOPHILIC SULFATE-REDUCING BACTERIUM DESULFOTOMACULUM-THERMOACETOXIDANS SP-NOV

An obligately anaerobic thermophilic sporeforming sulfate-reducing bacterium, named strain CAMZ, was isolated from a benzoate enrichment from a 58°C thermophilic anaerobic bioreactor. The cells of strain CAMZ were 0.7 μm by 2-5 μm rods with pointed ends, forming single cells or pairs. Spores were central, spherical, and caused swelling of the cells. The Gram stain was negative. Electron donors used included lactate, pyruvate, acetate and other short chain fatty acids, short chain alcohols, alanine, and H2/CO2. Lactate and pyruvate were oxidized completely to CO2 with sulfate as electron acceptor. Sulfate was required for growth on H2/CO2, and both acetate and sulfide were produced from H2/CO2-sulfate. Sulfate, thiosulfate, or elemental sulfur served as electron acceptors with lactate as the donor while sulfite, nitrate, nitrite, betaine, or a hydrogenotrophic methanogen did not. The optimum temperature for growth of strain CAMZ was 55-60°C and the optimum pH value was 6.5. The specific activities of carbon monoxide dehydrogenase of cells of strain CAMZ grown on lactate, H2/CO2, or acetate with sulfate were 7.2, 18.1, and 30.8 μmol methyl viologen reduced min-1 [mg protein]-1, respectively, indicating the presence of the CO/Acetyl-CoA pathway in this organism. The mol%-G+C of strain CAMZ's DNA was 49.7. The new species name Desulfotomaculum thermoacetoxidans is proposed for strain CAMZ. © 1990 Springer-Verlag.