Theodore Tran

Nitrogen fixation is the conversion of nitrogen gas into ammonia. In many environments, nitrogen is a limiting nutrient for growth. Anthropogenic sources of nitrogen supplement nitrogen fixation, but this process is energy intensive. As a more sustainable and long-term solution, organisms that perform nitrogen fixation (only known in members of the bacteria and archaea) are of extreme interest. While nitrogen fixation in bacteria has been well investigated, the genetic factors driving nitrogen fixation in archaea are still being determined. To learn more about nitrogen fixation in archaea, I focus on the model organism Methanococcus maripaludis. Two new genes were identified through transposon-mutagenesis to play a role in nitrogen fixation. These genes are annotated to encode for a hypothetical protein and a Major Facilitator Superfamily (MFS) transporter. To determine their importance, I generated mutants lacking these two genes and assessed their growth under nitrogen-fixing conditions. The results support that these genes play an important role in nitrogen fixation. Complementation of the MFS transporter gene restored the ability to fix nitrogen while complementation of the hypothetical protein gene did not. This research has helped to shed light on how nitrogen fixation is performed in archaeal species and has showcased avenues for future research in understanding the vastly understudied metabolism of archaea. Finally, it has provided a first step in helping to explore new ways in which to confront nitrogen deficiencies impacting biological ecosystems.