Date of Graduation

Fall 2024

Degree

Master of Science in Biology

Department

Biology

Committee Chair

Babur Mirza

Abstract

Waterborne pathogens from human fecal matter pose a significant health risk in karst environments, where domestic wastewater can easily be transferred to the shallow groundwater system via old, leaky septic tanks and damaged sewer lines. This study monitored fecal indicator bacteria (FIB) and potential pathogens in Sequiota Spring located in the karst region of southwest Missouri, using Microbial Source Tracking (MST) and Illumina DNA sequencing of bacterial 16S rRNA genes. MST identified high levels of human fecal indicator bacteria (HFIB) (up to 110,000 cells/L) in July 2020. By June 2022, HFIB levels had dropped significantly (55-fold reduction) after the City of Springfield replaced old clay sewer pipes in the upstream catchment area. Similarly, 16S rRNA sequencing showed reduced Enterobacteriaceae DNA sequences post-repair, although sequences related to Campylobacteraceae and Legionellaceae increased slightly in the summer of 2022. Waterfowl FIB levels remained low (~300 cells/L) and stable from 2019 to 2022, suggesting that sewer repairs were the primary driver of HFIB reduction. This study highlights the effective use of combined laboratory techniques and fieldwork in addressing nonpoint human fecal contamination at Sequiota Spring.

Keywords

waterborne pathogens, bacterially impaired watersheds, distribution of Legionellaceae, Enterobacteriaceae, Bacteroidaceae, and Campylobacteraceae-related pathogens, qPCR, high-throughput sequencing

Subject Categories

Bacteriology | Biodiversity | Biotechnology | Cell Biology | Environmental Microbiology and Microbial Ecology | Pathogenic Microbiology

Copyright

© William J. Durstock

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