Research: Project 2

Identifying the enzymatic mechanism of N₂O biosynthesis, a potent greenhouse gas

 

Nitrous oxide (N₂O) is a potent greenhouse gas that is a significant contributor to climate change, with a global warming potential ~300 times greater than that of CO₂ on a 100-year time scale. In addition, N₂O is also a major cause of stratospheric ozone depletion and production of ground level ozone. Current global N₂O levels (325 ppb) are 19% higher than pre-industrial levels and continue to rise at a rate of 0.25% per year.

The major cause of human-induced N₂O production is the excessive usage of nitrogen-based fertilizers, which intensifies microbial N₂O production pathways (i.e., nitrification and denitrification) as depicted in the figure below. To devise effective mitigation strategies, a process-level understanding of N₂O formation and consumption is needed. We are using stable isotopes (e.g., ¹⁴N and ¹⁵N) to probe the mechanism of enzymes involved in N₂O biosynthesis. In particular, by studying the isotopic preference of the central (α) and terminal (β) positions of N₂O, we can quantitatively distinguish N₂O production pathways and identify N₂O sources

Microbial sources of N₂O production in the soil. Adapted from: Frontiers in Environmental Science (2014), 2, article 5 (p. 1-10).