MILK EXOSOME-DRIVEN EVOLUTION OF ANTIBIOTIC-RESISTANT GUT PATHOGENS

Objective 1. Assess the selection of polymorphisms in C. difficile and vancomycin-resistant E. faecalis in milk exosome-defined cultures. This objective tests the hypothesis that the presence of milk exosomes in culture will select for genetic polymorphisms that may enhance or diminish virulence-associated phenotypes that can be measured in vitro compared to bacteria prior to passaging (reference genome).Objective 2. Assess whether milk exosomes cause changes in the host microbiome that alter the colonization of mice with C. difficile and E. faecalis not selected in exosome cultures. This objective tests the hypothesis that feeding milk exosome and RNA-depleted (ERD) diets and milk exosome and RNA-sufficient (ERS) diets causes changes in microbial communities in the murine gut that alter the susceptibility to challenges with pathogens.Objective 3. Assess the pathogenicity of in vitro-selected polymorphisms in mice fed a regular AIN-93G diet. This objective tests the hypothesis that C. difficile and E. faecalis selected in milk exosome-free (E-Minus) cultures cause disease phenotypes that differ in severity compared to phenotypes caused by C. difficile and E. faecalis selected in milk exosome-supplemented (E-Plus) cultures.