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Author ORCID Identifier


Open Access Dissertation

Document Type


Degree Name

Doctor of Philosophy (PhD)

Degree Program


Year Degree Awarded


Month Degree Awarded


First Advisor

Lynne McLandsborough

Subject Categories

Bacteriology | Food Microbiology | Genomics | Pathogenic Microbiology


The presence of bacterial contamination on surfaces that come in contact with foods is a significant problem in the food industry. A wide spectrum of pathogens including Salmonella enterica contaminate food and water, leading to serious outbreaks and even death. Most techniques currently available for detecting microbial contamination and for evaluating the efficacy of antimicrobial compounds have significant limitations. In this project, we have developed an optical screening method using the oCelloScope which can rapidly estimate the efficacy of various antimicrobial compounds simultaneously. Our method achieves this by quantifying the number of surviving bacterial cells using the oCelloScope, expressed as microbial log reduction (MLR), after treatment with antimicrobial compounds. Additionally, we have worked on the development of novel antimicrobials against Salmonella enterica which overcomes the limitations of wet and dry sanitization strategies commonly used in the food industry. Food-grade oils acidified with fatty acids such as acetic acid were found to be highly effective against S. enterica contamination. The use of formulated oils as sanitizers opens the possibility of using elevated temperatures, thus eliminating processing downtimes associated with dry sanitization. During sanitization, there is always a possibility for contaminating bacteria to be exposed to sub-lethal concentrations of antimicrobial compounds which enhances the resistance and tolerance of the bacteria towards subsequent antimicrobial treatments. In this project, we have also studied the genetic changes in S. enterica after exposure to sub-lethal concentrations of acetic acid. We have used an adaptive evolutionary approach to understand the genomic, transcriptomic, and phenotypic changes in S. enterica subjected to long-term acid stress. The research conducted in this dissertation project holds practical applications for food safety and public health. S. enterica contamination of food products are a major health concern, and hence, its rapid detection, development of new and improved antimicrobial formulations against it, along with understanding the genomic basis of its stress adaptation is essential. The overall goal of this project is to develop efficient methods for increasing safety levels in the food industry and understanding stress adaptation in foodborne pathogens with the hope that it helps to improve global food safety.


Available for download on Thursday, August 01, 2024