[Fixation of molecular nitrogen by sulfate-reducing bacteria from petroleum strata]

The activity of nitrogen fixation by the museum strains of sulfate reducing bacteria isolated from oil deposits was studied using the acetylene technique. The mesophilic sulpfate reducing bacteria belonging to the species Desulfovibrio africanus 2372 and D. baculatus X were found to have a high nitrogenase activity. D desulfuricans subsp. aestuarii 2198 reduced acetylene at a low rate. The thermophilic sulfate reducing cultures of D. thermophilus 7, Desulfotomaculum nigrificans 781 and Dm. nigrificans subsp. salinus 435 produced only small quantities of ethylene. Apparently, nitrogen fixation by sulfate reducing bacteria can be considerable in oil strata whose temperature does not exceed 35--40 degrees C.