[Thermophillic sulfate-reducing bacteria from oil-bearing strata]

The paper describes pure cultures (strains 435 and 781) of thermophilic spore-forming sulphate-reducing bacteria isolated from oil strata. The strain 435 was classed as a new subspecies Desulfotomaculum nigrificnas subsp. salinus according to its morphological, physiological, and biochemical characteristics. The cells of the culture are rod-like, 2-5 mcm long and 0.9-1.3 mcm thick. Some cells are spindle-shaped. The cells have peritrichously arranged flagella. Spores are oval, located terminally or subterminally, slightly widening the cells. The culture is an obligate anaerobe. It grows in media containing sulphates and assimilates sodium salts of lactic, pyruvic, malic and formic acids, ethanol, and butanol. The cuture assimilates pyruvate in the absence of sulphates. Sulphate, sulphite and thiosulphate are electron acceptors when the culture grows on lactate. The organism can grow at 40-70 degrees C, the optimum temperature being 60 degrees C. It requires NaCl for growth, and can grow even in the presence of 4% NaCl in the medium. The optimum should contain 1% NaCl and microelements. Desulfoviridin is absent. The cells contain a cytochrome of the protoheme class. The content of G + C base pairs in DNA is 57.0 +/- 0.5 mol. %.