Publication Date

2026

Document Type

Dissertation/Thesis

First Advisor

Singh, Pallavi

Degree Name

Ph.D. (Doctor of Philosophy)

Legacy Department

Department of Biological Sciences

Abstract

Contamination of meat samples from pathogens such as Shiga toxin-producing E. coli (STEC), especially in ruminants, is an ever-growing issue for the safety of global meat production. Recent studies have reported STEC in the livestock and food industry with a limited focus on wildlife. Although cattle serve as the primary reservoir for STEC, American bison (Bison bison bison) is the largest ruminant inhabiting North America, sharing similar genetics, and grazing habits, making them an ideal alternative STEC reservoir. Re-introduction for prairie conservation and meat farming has brought bison herds closer to anthropic environments than before. Recently bison meat has become an increasingly popular protein choice, marketed as a healthier alternative to beef increasing consumption. These factors increase the transmission of pathogens like STEC to humans via the fecal-oral route. STEC-infected meat consumption can lead to diarrhea or Hemolytic Uremic Syndrome (HUS) in severe cases, causing a significant healthcare burden and economic loss. STEC ingested by ruminants like bison encounter the native intestinal microbiome which can be studied non-invasively by inferring the microbiome of freshly laid fecal samples. Studies on the intestinal microbiome of cattle have shown differences when colonized by STEC making microbiome a factor influencing STEC colonization in ruminants like bison. The objective of our study was to detect STEC in bison feces and investigate the role of microbiome in STEC colonization. Our rigorous methodology comprises sample collection, pathogen enrichment, metagenomics, and functional analysis, which will provide a comprehensive view of this complex system. We longitudinally collected 844 freshly laid fecal samples from four bison herds stationed in Lee, Livingston, Douglas and Kankakee counties in Illinois, four times a year, corresponding to each season over a two-year period. To detect STEC from bison feces, enrichment, isolation, and PCR confirmation using stx toxin-specific primers was performed. STEC belonging to non-O157 serotypes were detected in bison. This was followed by metagenomic analysis of the bison fecal microbiome using NGS techniques. We conducted multi variate analysis of the microbiota to understand how it can protect against STEC colonization in bison. The fecal microbiota structure and microbial interactions between STEC colonized compared to non-colonized bison will provide insights into how STEC influences the native microbial communities and overall ecology leading to STEC presence. Our study serves as an early warning for possible STEC dissemination through bison feces to nearby crops or livestock. Scientific data generated from our study will help with designing better biosecurity measures to prevent transmission of STEC from bison to humans. This way the results from the study may contribute to safer bison meat production with fewer cases of STEC outbreaks and meat spoilage from fecal contact.

Extent

215 pages

Language

en

Publisher

Northern Illinois University

Rights Statement

In Copyright

Rights Statement 2

NIU theses are protected by copyright. They may be viewed from Huskie Commons for any purpose, but reproduction or distribution in any format is prohibited without the written permission of the authors.

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Text

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