Biochemistry and Physiology of Denitrification by Marine Bacteria.

P. perfectomarinus was found to grow anaerobically at the expense of nitrate, nitrite or nitrous oxide but not chlorate or nitric oxide. In several repetitive experiments, anaerobic incubation in culture media containing nitrate revealed that an average of 82 of the cells in aerobically grown populations were converted to the capacity for respiration of nitrate. Although they did not form colonies under these conditions, the bacteria synthesized the denitrifying enzymes within 3 hr in the absence of oxygen or another acceptable inorganic oxidant. This was demonstrated by the ability, after anaerobic incubation, of cells and extracts to reduce nitrite, nitric oxide and nitrous oxide to nitrogen. From crude extracts of cells grown on nitrate, nitrite or nitrous oxide, separate complex fractions were obtained that utilized NADH as the source of electrons for the reduction of 1 nitrite to nitric oxide, 2 nitric oxide to nitrous oxide, and 3 nitrous oxide to nitrogen. Gas chromatographic analyses revealed that each of these fractions reduced only one of the nitrogenous oxides. Author