The preferred electron acceptor of Desulfovibrio desulfuricans CSN
Abstract The sulfate-reducing bacterium Desulfovibrio desulfuricans strain CSN (DSM 104) oxidized H2 with thiosulfate, sulfate, sulfite, nitrite, nitrate and oxygen with rates increasing (in the order listed) from 20 to 525 nmol H2 min−1 mg−1 protein. Nitrate reduction was induced by nitrate or limiting concentrations of sulfate during growth, while all other activities were constitutive. Oxygen prevented reduction of all other electron acceptors, while nitrate and nitrite blocked the reduction of the sulfur compounds. In the presence of H2 and reduced sulfur compounds, H2 was the preferred electron donor. The cells oxidized thiosulfate or sulfite coupled to the reduction of nitrate to ammonia. This represents a novel type of metabolism connecting the sulfur and nitrogen cycles. It is concluded that oxygen is the preferred electron acceptor of D. desulfuricans. Sulfate reduction in oxic environments must be due to different organisms or mechanisms.