Nitrogen Cycling and Nitrous oxide (N2O)

Nitrogen pollution and climate change are two of the direst threats to environmental sustainability. Along with nitrogenous contaminants originating from sewers, a large portion of nitrogen added to agricultural soils as fertilizers is leached into the natural waters to cause eutrophication and subsequently, a substantial increase in frequency and intensity of marine, lacustrine, and riverine algal blooms is observed across the globe. The dramatic increase in the atmospheric greenhouse gas concentrations that we have seen over the past two centuries has resulted in substantial and dire consequences to the global climate.

The microbial nitrogen cycling is of utmost importance to both of these sustainability issues. Proper removal of nitrogen from the sewers is only possible via the utilization of microbial processes such as nitrification, denitrification, and anammox. The key to efficient nitrogen fertilization lies in limiting nitrification and denitrification in agricultural soils. Nitrous oxide (N2O), produced and released primarily from many different nitrogen cycling reactions, has a greenhouse gas potential ~300 times greater than CO2 and accounts for ~6 percent of the total greenhouse gas emission. An improved understanding of N2O dynamics in soil, aquatic, and built environments is crucial for N2O emission mitigation.


The Environmental Microbiology Laboratory at KAIST investigates various approaches for improved nitrogen management and N2O emission mitigation.

Research Project #1

   Circular nitrogen management utilizing DNRA (dissimilatory nitrate reduction to ammonium

Research Project #2

   Utilization of N2O-reducing bacteria for mitigation of N2O emissions

Research Project #3

   Functional metagenomic & metatranscriptomic analyses of environmental nitrogen-cycling  genes