Determining the Efficacy of a Dairy-Origin Probiotic, Propionibacterium freudenreichii subspecies freudenreichii, against Multidrug-Resistant Salmonella Heidelberg in Turkeys

University of Minnesota Ph.D. dissertation. February 2018. Major: Animal Sciences. Advisor: Anup Kollanoor Johny. 1 computer file (PDF); xiv, 172 pages.Poultry contributes to more than half of foodborne salmonellosis in the U.S. through contaminated meat, eggs, and other products. Recently, Salmonella Heidelberg (SH) has emerged as a major serovar transmitted to humans via poultry. Cecal colonization of SH and consequent fecal shedding of the pathogen contaminate the environment and carcasses, necessitating interventions to control SH in poultry. Efficacy of a dairy-originated non-host specific probiotic bacterium, Propionibacterium freudenreichii subsp. freudenreichii NRRL 3523 (PF), against a multidrug-resistant (MDR) SH in turkeys has been narrated in this thesis. In vitro experiments revealed that PF reduced the virulence factors of SH associated with its colonization in the host (P0.05). Further, the efficacy of PF against SH colonization and its dissemination to internal organs such as liver and spleen in turkeys were validated using in vivo experiments in 2-, 7-, and 12-week-old commercial turkeys. A high PF viability in turkey cecum (3.5-5.0 log10 CFU/ml) was observed in different age group turkeys after supplementing 1010 CFU/ml through drinking water. The PF supplementation resulted in 1.6 to 2.2-, 1.0 to 1.3-, and 1.7- to 2.6- log10 CFU/g reduction of SH in the cecum of turkeys at 2-, 7- and 12-week, respectively (P<0.05), compared to the controls. A reduced dissemination of SH to liver and spleen (P<0.05) also resulted. Populations of PF increased the relative abundance of several production-associated beneficial bacteria, including carbohydrate fermenting and short chain fatty acid producing groups (P<0.05). However, SH inoculation caused an increase in abundance of microflora associated with inflammatory response (P