Mechanisms of Bacterial Pathogen Internalization Into Fresh and Fresh-Cut Fruits

Salmonella enterica and Listeria monocytogenes have been implicated in numerous recent foodborne disease outbreaks linked to fresh and fresh-cut fruits such as cantaloupes, tomatoes, cucumbers and apples. However, the specific mechanisms that mediate the internalization and survival of these pathogens within fruits have not been fully elucidated. The overall goal of this project is to identify and characterize bacterial determinants, fruit attributes and processing factors that collectively lead to the infiltration and transfer of S. enterica and L. monocytogenes into different types of fresh and fresh-cut fruits linked to recent foodborne disease outbreaks. Combined microscopic, microbiological, molecular and genomic approaches will be used to study the physical and molecular mechanisms used by S. enterica and L. monocytogenes outbreak strains to internalize apple, cantaloupe, tomato, and cucumber during hydrocooling and cutting that are most relevant to postharvest industry processing and retail practices and likely lead to pathogen internalization. Results from this project will fill important knowledge gaps regarding the routes and patterns of pathogen internalization, as well as the fate of the internalized pathogens in fresh and fresh-cut fruits. New knowledge in this regard will provide important scientific basis for regulatory agencies and food industry to develop more effective control measures to mitigate contamination in these food commodities.