Kinetics of nitrate utilization by mixed populations of denitrifying bacteria.

Kinetics of nitrate utilization by mixed bacterial populations from two agricultural soils and a pond sediment in Kentucky were measured by using progress curves of nitrous oxide production. Nitrous oxide production from anaerobic soil and sediment slurries containing added nitrate and acetylene exhibited first-order kinetics. Nitrate affinity (K(m)) for mixed populations of denitrifying bacteria in unfertilized agricultural soils and pond sediments ranged from 1.8 to 13.7 muM. The affinity of bacterial populations for nitrate did not vary with habitat, and the ability to use low concentrations of nitrate was retained by bacterial populations living in environments which received large inputs of nitrate.