Date of Award
5-1-2024
Degree Name
Master of Science
Department
Molecular Biology Microbiology and Biochemistry
First Advisor
Hamilton-Brehm, Scott
Abstract
The investigation of microbial nitrate removal pathways in the environment has received growing attention in recent decades. Nitrate loading is a leading cause of eutrophication, and thus contributes to the collapse of multiple ecosystem services and is a cause of concern for public health. This study investigates nitrate removal processes in southernmost Illinois by analyzing DNA from environmental communities derived from sediment cores taken from a variety of land uses with varying flood regimes. Investigative methods include metagenomic analyses using amplicon sequence variants (ASVs) derived from next generation sequencing (NGS) data, PCR, alpha and beta diversity comparisons, and in silico methodologies to determine the presence or absence of genes associated with nitrate removal, the effects of spatial, seasonal, and flood regime variability on community-level taxonomic distributions, and the effect of various environmental conditions on community assemblages existing within the Dogtooth Bend region of Southern Illinois. Some nitrate removal pathways are shown to exist within the study area, spatial variability was more determinative of community assemblages than season or flood regime, and pH is shown to be the primary driving factor of dissimilarities in beta diversity among the representative samples. To understand the full extent of nitrate removal processes in the environment, efforts to improve sampling depth of microbial communities and to further understanding of microbial ecology must occur.
Access
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