The global nitrogen cycle has been profoundly disturbed by industrial fertilizer production, resulting in an enhancement of global warming, air and water pollution, and biodiversity loss. Biological nitrogen fixation, catalyzed by the microbial metalloenzyme nitrogenase is nature's original solution to fertilizer production and is a key parameter used to estimate human disruption of the nitrogen cycle. We know little of the rates and controls on environmental N2 fixation by different trace metal forms of nitrogenase. This affects our understanding of ecosystem fertility as well as strategies to manage food and energy supplies. At Princeton, we have developed new methods that distinguish the activity of canonical Mo- and alternative V- and Fe-only nitrogenases and are applying these methods to better understand the controls on environmental N2 fixation at scales ranging from metabolites to ecosystems.
Zhang X, McRose DL, Darnajoux R, Bellenger J.P, Morel FMM, Kraepiel AML. 2016. Alternative nitrogenase activity in the environment and nitrogen cycle implications. Biogeochemistry. 127(2-3):189-198. doi: 10.1007/s10533-016-0188-6
Zhang X, Sigman DM, Morel FMM, Kraepiel AML. 2014. Nitrogen isotope fractionation by alternative nitrogenases and past ocean anoxia. Proceedings of the National Academy of Sciences. 111(13):4782-4787.doi: 10.1073/pnas.1402976111
Bellenger J.-P., Xu Y., Zhang X., Morel F.MM, Kraepiel A.M.L. 2014. Possible contribution of alternative nitrogenases to nitrogen fixation by asymbiotic N2-fixing bacteria in soils. Soil Biology and Biochemistry. 69:413-420. doi: 10.1016/j.soilbio.2013.11.015