Thesis Format
Integrated Article
Degree
Master of Science
Program
Biology
Supervisor
Garnham, Christopher P.
Affiliation
Agriculture and Agri-Food Canada, The University of Western Ontario
2nd Supervisor
Thorn, Greg
Co-Supervisor
Abstract
Plant pathogenic fungi throughout the agricultural supply chain produce mycotoxins, which are harmful secondary metabolites that aid fungal colonization and contaminate food and feed. Consuming mycotoxin-contaminated products poses health risks to humans and animals. While several strategies to limit mycotoxin contamination exist, enzymatic biotransformation of mycotoxins into non-toxic forms offers a potentially safe, specific, and robust solution to manage mycotoxins. To identify novel mycotoxin degradation activities, an in-house developed discovery-based pipeline was employed to culture various mixed microbial communities with mycotoxins. Using the pipeline, a novel thermophilic bacterium that degrades Ochratoxin A was discovered. Additionally, a zearalenone hydrolase previously identified with the pipeline was biochemically characterized and demonstrated to hydrolyze additional resorcylic acid lactones beyond zearalenone, including radicicol. Radicicol inhibits the activity of Heat Shock Protein 90, however following enzymatic treatment, this activity was significantly attenuated. Identifying mycotoxin degradation activity supports continued agricultural production while preserving economic and health interests.
Summary for Lay Audience
Pathogenic fungi produce mycotoxins, small molecules that weaken plant defenses and help fungi cause infections. Mycotoxins can form before harvest in the field or after harvest during storage, contaminating crops like wheat, barley, and corn. Depending on the level of contamination, crops may need treatment to remove mycotoxins, or, in severe cases, be destroyed. In bad years, mycotoxin contamination can cost producers billions annually, while consumption of tainted products can harm human and animal health. Management strategies include pre-harvest actions like soil management, fungicide use, crop rotation, and breeding resistant varieties. Post-harvest, methods include sorting contaminated products, binding toxins with agents, or using enzymes to modify mycotoxins' structure. While some strategies can affect product quality, enzymes offer a promising way to transform mycotoxins into non-toxic forms. Enzymatic degradation of mycotoxins is a growing research field and could provide a safe and effective solution. Chapter 1 covers mycotoxin background, production, and detoxification methods. Chapter 2 discusses the discovery of a heat-stable bacterium from ginseng soil that can degrade Ochratoxin A, a harmful mycotoxin. Chapter 3 focuses on the biochemical characterization of an enzyme, discovered in the Garnham lab, that degrades Zearalenone, another mycotoxin. This enzyme can also degrade similar compounds. Chapter 4 explores the applications of these findings and potential future research. As mycotoxins continue to threaten agriculture, it’s important to develop new strategies. Enzymatic biotransformation offers a safe, targeted, and cost-effective approach.
Recommended Citation
Hendricks, Kyle N., "Identification and Characterization of Novel Mycotoxin Degrading Enzymes" (2024). Electronic Thesis and Dissertation Repository. 10571.
https://ir.lib.uwo.ca/etd/10571
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This work is licensed under a Creative Commons Attribution 4.0 License.