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Control of Food-Borne Pathogens in Pre-and Post-Harvest Environments


Develop or improve methods for control or elimination of pathogens in pre-and post harvest environments including meat, poultry, seafood, fruits and vegetables and nutmeats.

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NON-TECHNICAL SUMMARY: A comparison of the frequency of isolation of different Salmonella enterica serovars from clinical human and from non-clinical nonhuman sources has been used as an indicator of the animal origin of serovars causing human Salmonellosis. Of the top 10 isolates from chickens, six are also among the top 10 from humans. Interestingly, the predominant isolate from chickens, serovar Kentucky, is not found among the top 20 serovars isolated from humans. The goal of the study is to determine factors that underlie this phenomenon. <P>APPROACH: Detection of Salmonella enterica Kentucky virulence genes and of genes involved in the synthesis of cell binding factors will be carried out by PCR. Invasion assays will be done with HCT8 cells or chicken embryo hepatocytes and will follow established procedures that involve the use of gentamycin to kill bacteria that have not invaded target cells and lysis of target cells to release bacteria that were able to invade. Physiological and stress survival tests will be done in 96-well microtiter plates. Effect of stresses such as exposure to high or low temperatures, antimicrobial compounds and acids and salt on growth will be determined by plating methods. The ability of the Salmonella isolates to form biofilms will be determined by the crystal violet staining method. Proteomic analyses to determine differences in protein expression patterns between S. e. Kentucky and other S. e. isolates will be done by two-dimensional protein gel electrophoresis and gene expression analysis will be accomplished in collaboration with a lab that is in possession of a S. e. Typhimurium gene array.

Kniel-Tolbert, Kalmia; Hoover, Dallas; Chen, Haiqiang
University of Delaware
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