Abstract
The biological reduction of N(2)O, a potent greenhouse gas, is crucial for environmental sustainability. We developed an automated system for continuous N(2)O monitoring in the gas phase of a flask containing an anaerobic bradyrhizobial culture, and then exami-ned the kinetic parameters of bacterial N(2)O reduction. The maximum reaction rate (V(max)) was approximately 61-fold higher for Bradyrhizobium ottawaense SG09 (1,471 nmol h(-1) 10(9) cells(-1)) than for B. diazoefficiens USDA110 (24 nmol h(-1) 10(9) cells(-1)). Our kinetics anal-ysis confirmed that SG09 maintained higher N(2)O-reducing activity than USDA110 even at the atmospheric concentration of N(2)O (0.34 ppm).