Nitrous oxide flux: what microbial physiology can do to mitigate climate change gas production

Nitrous oxide is a major contributor towards greenhouse gas emissions from agriculture and is the most significant single cause of ozone depletion in the 21st Century. In this chapter, the microbial processes associated with the production and consumption of nitrous oxide are reviewed, with a focus on the role of NosZ in nitrous oxide removal. Recent developments have led to a recognition that two distinct clades of nosZ exist, and that diversity exists within and between the clades resulting in functional diversity of NosZ in the organisms that carry them. We point out areas where there are knowledge gaps, particularly a lack of exploration of the comparative biochemistry of NosZ from organisms beyond a few laboratory model species. We discuss the importance of considering how nitrous oxide is measured, and the ways in which factors such as evolutionary selection pressure, regulation, and biochemical organisation impact on the eventual activity of nitrous oxide reduction in biological ecological systems. This is followed by a set of perspectives on how we might apply our current and future knowledge to mitigate atmospheric nitrous oxide accumulation for global benefit.