STUDY OF THE DENITRIFYING ENZYMATIC SYSTEM OF COMAMONAS SP STRAIN SGLY2 UNDER VARIOUS AERATION CONDITIONS WITH A PARTICULAR VIEW ON NITRATEAND NITRITE REDUCTASES

This paper studies the effect of oxygen on the denitrifying enzymatic system of Comamonas sp. It is shown that nitrate respiration can take place in the presence of oxygen. Indeed, even if a protein synthesis i nhibitor is added in the medium, immediate nitrate consumption is obse rved in an aerobic culture inoculated with cells that have never been subjected to nitrate. Existence of a constitutive nitrate reductase co uld explain this phenomenon. Moreover the nitrate and nitrite reductas es are active and synthesized under aerobic conditions. The different levels of inhibition of nitrate reductase activity by respiratory inhi bitors and detergent, according to the aerobic and anaerobic cultures, might suggest the existence of a double nitrate reductase enzymatic s ystem.