Gene Expression Response of Salmonella to Multiple Hurdle Carcass Processing Interventions

Approach: Salmonella gene expression in response to processing interventions will be examined. Two Salmonella serotypes that are frequently associated with cattle, Newport and Muenster, will be used in this study. Both strains to be used were isolated from cattle hides and final carcasses (post intervention) at slaughter. The genome sequence of both strains will be determined by 454 sequence analysis. The strains will be cultured and then exposed to commonly used carcass processing interventions, including hot water, organic acid and cold temperature exposure. Salmonella mRNA will be isolated, before and after intervention exposure, and will then be converted to cDNA. Gene expression profiles will be determined by 454 cDNA sequence analysis. Gene identities and relative abundance of sequenced cDNA will be determined by comparisons with annotated reference genomes. Physical assays of Salmonella viability and resistance to acid and oxidative stress, before and after intervention exposure, will also be determined.