Molecular Analysis of Foodborne Pathogen Responses to Stressors

Objective 1: Characterization of environmental and food-related stress responses of Shiga-toxin producing Escherichia coli (STEC). Sub-objective 1.1: Analysis of STEC O157:H7 responses to acid, heat and biocides with emphasis on the role of RpoS and Rcs regulons. Sub-objective 1.2: Genomic adaptation of environmentally-adapted STEC O157:H7 upon exposure to synthetic gastric fluid. Sub-objective 1.3: Genomic adaptation of environmentally-adapted STEC O157:H7 upon exposure to SOS-inducing stress. Objective 2: Molecular analysis of Campylobacterâ¿¿s responses to biotic and abiotic stresses encountered in host- and food-environments. Sub-objective 2.1: Consequences of Campylobacter exposure to short-chain fatty acids. The molecular level effects on motility, attachment/invasion of eukaryotic cell lines, and biofilm formation. Sub-objective 2.2: Campylobacter molecular responses during co-incubation with bacteria isolated from poultry environments. The effects the other bacteria have on Campylobacter survival, aggregation (auto-aggregation and co-aggregation), attachment and biofilm development on poultry skin. Objective 3: Molecular analysis of Listeria monocytogenesâ¿¿ responses to biotic and abiotic stresses encountered in food and food-processing environments. Sub-objective 3.1: Studies of sanitizer- and stress-induced viable-but-nonculturable (VBNC) state in L. monocytogenes. Sub-objective 3.2: Investigation of molecular responses of L. monocytogenes exposed to modiffied atmosphere packaging (MAP) in chicken meats using transcriptomics. Sub-objective 3.3: Investigation of genome evolution of L. monocytogenes exposed to long-term nutrient-limiting, non-selective stress condition. Objective 4: Phenotypic and genetic characterization of extra-intestinal pathogenic Escherichia coli (ExPEC) isolated from poultry and produce. Sub-objective 4.1: Analysis of ExPEC isolated from chickens and humans: biofilm assays, virulence gene profiles, antimicrobial resistance profiles, whole genome comparison of ExPEC strains isolated from chicken and human infections. Sub-objective 4.2: Transcriptomics of ExPEC strains in chicken meat.