The Identification Of Fermentative Bacteria And The Anaerobic Microbial Effect On Crude Oil Degradation

The paper was chiefly concerned in the physiological, biochemical properties and the metabolites of fermentative bacteria from oil production water, together with the anaerobic microbial effect on crude oil biodegradation under different pathways. The consults comprised: (1) Seven fermentative bacteria were isolated from oil production water. The isolates belonged to four different species, such as strains SC-2,SC-5,OX1-1 and LD2-1 were most closely to Desulfotomaculum and strain DS-1 was most closely to Desulfovibrio, as well as strain L-5-2 was belonged to Thermosipho. (2)The strains SC-2 and SC-5 were extremely thermophilic, anaerobic bacteria with maximum temperature at 75℃. Fermentation end products of glucose were ethanol, acetate, lactate, carbon dioxide and hydrogen. (3) The enrichment with crude oil degraded moderately as carbon resource was inoculated six month at 60℃under nitrate-reducing, sulphate-reducing and methanogenic condition. The investigation of the microbial communities indicated that bacterial communities had changed in different degree under three metabolic pathways, moreover, archaeaen communities showed great difference under methanogenic condition. The 16Sr RNA gene clone library of archaea was constructed and sequence analysis revealed that archaea were affiliated with Methanomicrobiales, Archaeoglobales and Methanosarcinales. The content of asphaltene and nonhydrocarbon had increased and C₂₉25-norhopane/ C30hopane increased constantly, which revealed that C30hopane tended to be biodegraded to C₂₉25-norhopane. Methane was produced after incubation. The 13δCPDB of methane distributed from -66‰to -75.3‰, 13δCPDB of carbon dioxide was from -2.4‰to 0.25‰, which the data accorded with generally accepted carbon isotope of biogas. It was the first research on obligately anaerobic biodegradation of crude oil at 60℃under three different metabolic pathways at home, moreover, it was the first report that C30hopane was degraded to C₂₉25-norhopane during anaerobic biodegradation of crude oil.