My research focuses on marine nitrification, the oxidation of ammonia via nitrite to nitrate. In the ocean, these two processes are balanced, and the most abundant form of bioavailable N is nitrate, the end product of nitrification. Two microbial groups are responsible for marine nitrification - the ammonia oxidizers and nitrite oxidizers. While ammonia oxidizers are among the most abundant organisms on Earth, nitrite oxidizers are rare.
I combine bulk biogeochemical rate measurements with single cell analyses and molecular techniques to study how metabolic versatility and the use of simple organic N compounds contributes to the ecological success of marine ammonia oxidizers. Additionally, I investigate the factors that lead to the discrepancy in abundance between ammonia and nitrite oxidizers.