Temporal Change in Nitrous Oxide and Dinitrogen from Denitrification Following Onset of Anaerobiosis

摘要

Similar temporal patterns were found in three mineral soils for the composition of the gaseous products of denitrification following the onset of anaerobic conditions. During the early period of anaerobiosis (0 up to 1 to 3 h), N2 was the dominant product of denitrification. The NO3⁻ → N2O activity then increased, but was not accompanied by a corresponding increase in N2O-reducing activity. This resulted in a relatively extended period of time (1 to 3 up to 16 to 33 h) during which N2O was a major product. Eventually (after 16 to 33 h), an increase in N2O-reducing activity occurred without a comparable increase in the N2O-producing activity. The increase in the rate of N2O reduction did not occur in the presence of chloramphenicol and required the presence of N2O or NO3⁻ during the preceding anaerobic incubation. During the final period (16 to 33, up to 48 h), N2 was generally the sole product of denitrification, since the rate of N2O reduction exceeded the rate of N2O production. A similar sequential pattern was also found for a culture of a denitrifying Flavobacterium sp. shifted to anaerobic growth. A staggered synthesis of the enzymes in the denitrification sequence apparently occurred in response to anoxia, which caused first a net production of N2O followed by consumption of N2O.