GENOMIC AND PROTEOMIC ANALYSIS OF FOODBORNE PATHOGENS

1. Conduct a functional and molecular characterization of Shiga-toxin producing Escherichia coli (STEC) with specific emphasis elucidating the responses to food-related stresses, and genomic and proteomic studies to assess changes in virulence and pathogenicity. 1A: Comparative phylogenomics and phenomics of non-O157 STEC. 1B: Examine and compare stress responses, including acid tolerance, in E. coli O157:H7 and non-O157 STEC. 1C: Role of SdiA in acid tolerance of STEC O157:H7 and non-O157 STEC. 1D: Molecular serotyping of E. coli. 1E: Methods for detection and identification of non-O157 STEC. 2: Conduct functional and molecular characterization of Campylobacter species with specific emphasis on responses to intrinsic and extrinsic stresses through genomic and proteomic studies, and examination of morphological and physiological changes. 2A: Determine the ¿mode of action¿ by which polyphosphates (extrinsic stress) enhance the survival of C. jejuni and C. coli strains. 2B: Use genomic and/or proteomic studies to molecularly characterize Campylobacter¿s physiological response to food additives under poultry processing conditions. 2C: Determine if members of the microbial ecology of chicken exudates provide survival advantages/disadvantages to Campylobacter. 2D: Determine if common food additives change the composition of the microbial ecology of chicken exudate and if these changes are responsible for enhancing the survival of Campylobacter under food processing and storage conditions. 3: Conduct functional and molecular characterization of Listeria monocytogenes serotypes with specific emphasis on elucidating responses to food-related stresses through proteomics and genomics; and determining virulence differences among L. monocytogenes serotypes through sequencing and comparative genomics. 3A: Determine genes that are essential for the survival and growth of L. monocytogenes under weak organic acid conditions. 3B: Determine genetic responses of a pressure-resistant L. monocytogenes mutant exposed to the food preservative nisin. 3C: Determine genes responsible for the differences in virulence and stress responses among L. monocytogenes serotypes through sequencing, gene expression, and comparative genomics.