Kinetics and Microbial Ecology of Nitrous Oxide (N2O) Reduction by Denitrifying Bacteria

Given the concerns over nitrous oxide (N2O) formation during biological nutrient removal, a better and more quantitative understanding of N2O reduction by denitrifying bacteria is needed to predict the fate of N2O in wastewater treatment processes. In this research, kinetic parameters and yields were determined for a mixed culture of denitrifying bacteria. The effects of N2O on the microbial community structure were also assessed. A key finding was that denitrifying bacteria utilized N2O concurrently with either NO3− or NO2− Concurrent utilization provided higher growth rates than on NO3− or NO2− alone, and caused shifts in the community structure. This result suggests that the presence of N2O selects for bacteria that grow faster in the presence of N2O.