Variance Within Multiples Copies of NarG in Salt Marsh Sediments

Presenter: Jessica Hexter

Research Category: Physical and LIfe Sciences
College: College of Science
Major(s): Cell and Molecular Biology
Graduation Date: 2022

The study of the microbial nitrogen cycle is an important part of understanding how microbes contribute to and use greenhouse gases such as nitrous oxide and methane. As farmers have increased their use of nitrogen-based fertilizers (such as nitrate) it is even more important to understand the functioning of nitrate in microbial cycles. In coastal wetlands, the denitrification pathway accounts for 80.7% of nitrogen (N) removal by reducing nitrate to nitrogen gas. The first step on this pathway is facilitated by the gene narG. 2,459 metagenomically assembled genomes (MAGs) were analyzed to find MAGs that had multiple copies of narG and assess the diversity of those narG on the amino acid level. 1,372 MAGs had a total of 4,690 copies of narG throughout the entire depth profile and 86 genomes were found to have 10 or more copies of narG. The narG was observed to be highly variable, and that variance appeared to be grouped by depth. Of these microbes, only 7 of them contained the genes necessary for the complete denitrification pathway. This suggests that the reduction of nitrate to nitrite facilitated by narG has a greater biologically favorable function such as nitrate reduction coupled with methane oxidation of formate reduction.