Denitrification by Cytophaga johnsonae strains and by a gliding bacterium able to reduce nitrous oxide in the presence of acetylene and sulfide

Abstract

A gliding bacterium (Is-11), isolated for its ability to reduce nitrous oxide (N2O) in the presence of acetylene (C2H2) and sulfide, was able to use nitrate (NO3−), nitrite (NO2−), and N2O as terminal electron acceptors for growth. Similarly, of five strains of Cytophaga johnsonae examined, two were capable of complete denitrification. Two strains were unable to reduce nitrate and N2O, respectively, and the remaining strain lacked both nitrate and N2O reductases. However, in this strain the N2O reductase was induced by the presence of nitrite, but not nitrate. Acetylene inhibited N2O reduction but did not affect the reduction of nitrite or nitrate in all of the gliding bacteria tested. Sulfide temporarily inhibited all of the nitrogen oxide reductases. It did not relieve the C2H2 inhibition of N2O reduction in the C. johnsonae strains when tested under the same conditions under which C2H2 inhibition is relieved in Is-11.