2007 Annual Report 1a.Objectives (from AD-416) (1) Determine the persistence of Salmonella in swine manure as affected by dietary treatment. (2) Identify genes important for Salmonella colonization of the swine gastrointestinal tract and persistence in manure. 1b.Approach (from AD-416) (1) The effects of dietary treatment on the duration of Salmonella persistence in stored swine manure will be determined and a correlation between Salmonella persistence in manure and the native microbial community will be performed. (2) The role of quorum sensing on Salmonella swine colonization, shedding, and persistence in manure will be determined. (3) Genes required for Salmonella survival and persistence in swine manure will be elucidated. 4.Accomplishments Salmonella enterica serovar Typhimurium Colonization of the Swine Gastrointestinal Tract Due to Pathogen Sensing of Environmental Signals. The ability of Salmonella to sense and respond to its ever changing environment is critical for survival. Specific chemical signals that are present in the swine gastrointestinal tract may alert the pathogen to its location within the animal host. A mutation in a gene of Salmonella that is involved in sensing the environment, quorum sensing, was tested for its role in swine colonization. The wild-type and mutant strains were compared in vivo to determine their ability to colonize the swine gastrointestinal tract. The mutant strain had decreased colonization of the swine gastrointestinal tract compared to the wild-type strain. This research demonstrates that the sensing of specific environmental signals is important for Salmonella colonization of swine and suggests that inhibitors that target this bacterial sensing system may decrease or prevent colonization of animal hosts by this bacterial pathogen. This program is part of the National Program 108, Food Safety. Research contributes to Component 1.1 (Preharvest Food Safety – Animals); specifically addressing Problem Statements 1.1.3 (Ecology, Host Pathogen and Chemical Contaminants Relationships) and 1.1.4 (Intervention Strategies). 5.Significant Activities that Support Special Target Populations None. 6.Technology Transfer Number of non-peer reviewed presentations and proceedings 1 Number of newspaper articles and other presentations for non-science audiences 1 Review Publications Toscano, M.J., Stabel, T.J., Bearson, S.M., Bearson, B.L., Lay Jr, D.C. 2007. Cultivation of Salmonella enterica serovar Typhimurium in a norepinephrine-containing medium alters in vivo tissue prevalence in swine. Journal of Experimental Animal Science. 43(4):329-338.