OUR RESEARCH

Consumption of nitrous oxide (N₂O)

Various microbial and abiotic processes lead to the formation of N₂O a strong greenhouse gas. The only sink reaction for N₂O is the enzymatic reduction to inert dinitrogen (N₂). This function has traditionally been attributed to complete denitrifiers, which reduce nitrate and nitrite via N₂O to N₂. In 2012, an “atypical” Clade II N₂O reductase gene, nosZ, was discovered and found to be more abundant in many soil ecosystems than the known “typical” Clade I nosZ gene, suggesting that our understanding of the role of nosZ in controlling soil N₂O emissions was incomplete. Physiological studies demonstrated that bacteria with Clade II NosZ have higher growth yields with N₂O as electron acceptor and consume N₂O at lower concentrations. We work with axenic cultures, mixed cultures and mesocosms and explore how perturbations (e.g., fertilizer application, environmental change) affect the relative contributions of Clade I versus Clade II microorganisms and associated N₂O fluxes. This research contributes to a better understanding of N pools and fluxes, and reveals how perturbations, both natural and engineered, affect N cycling and N₂O emissions.