POPULATION AND GENETIC DIVERSITY ANALYSIS OF LISTERIA MONOCYTOGENES IN SELECT FOODS AND FOOD PROCESSING ENVIRONMENTS

Abstract

Listeria monocytogenes, a Gram-positive bacterium, is a foodborne pathogen that causes listeriosis in humans. L. monocytogenes can persist in various environmental conditions, including food-relevant conditions such as high salinity, refrigerated temperatures, and low moisture contents. Contaminated food products, including dairy products, deli meats, fresh produce, and soft cheeses, are the primary transmission vehicles for L. monocytogenes. The complex and dynamic population structure of L. monocytogenes complicates control efforts, particularly due to certain strains that may possess increased resistance to stress conditions and/or enhanced virulence. The advent of whole genome sequencing has facilitated comprehensive genomic analyses of L. monocytogenes, enabling a comprehensive understanding of its adaptation and survival characteristics over time and across various geographic locations. Understanding the population and genetic diversity of L. monocytogenes is crucial for the development of effective control measures, as it helps infer the spread and transmission pathways of L. monocytogenes through the integration of spatial-temporal factors. Furthermore, these analyses provide insights into the evolutionary relationships among L. monocytogenes strains. This dissertation aimed to investigate the population diversity of L. monocytogenes in various food sources and food processing facilities, utilizing the whole genome sequencing technology. The findings contribute valuable insights into the genetic diversity and population structure of L. monocytogenes, thereby aiding the understanding of the risk associated with L. monocytogenes contamination and the development of effective control measures to ensure food safety.