Denitrification by the fungus Cylindrocarpon tonkinense: anaerobic cell growth and two isozyme forms of cytochrome P-450nor

Analysis of the denitrification system of the fungus Cylindrocarpon tonkinense reveals the occurrence of distinct cell growth along with nitrite-dependent N2O formation. Respiration inhibitors suppress the N2O formation and/or cell growth, while ammonium ions exert no influence on these processes. Examination of purified Nor activity indicates that the activity depends on two isozymes of cytochrome P-405nor. Characteristics of these enzymes are compared.