EXPLORING THE EFFECTS OF GUT-DERIVED MICROBIAL METABOLITES ON EXPRESSION OF SPI-1 GENES AND ANTIMICROBIAL RESISTANCE IN SALMONELLA TYPHIMURIUM

Abstract

ABSTRACT Exploring the Effects of Gut-derived Microbial Metabolites on Expression of SPI-1 Genes and Antimicrobial Resistance in Salmonella typhimurium. (May 2014)

Rebekah Elizabeth Davis Department of Biology Texas A&M University

Research Advisor: Dr. Robert C. Alaniz Department of Microbial Pathogenesis and Immunology Texas A&M College of Medicine

The commensal bacteria that naturally inhabit the human gut are known to be beneficial to the host in a variety of ways, including producing compounds, such as indole and tryptamine, that reduce the invasion and colonization capability of enteric pathogens, such as Salmonella enterica serovar Typhimurium. Here we explore the effects of other tryptophan metabolites on the expression of genes that S. typhimurium uses for invasion into host cells: the Salmonella Pathogenicity Island-1 (SPI-1) genes. We also test whether smaller dosages of one tryptophan metabolite, indole, confers antimicrobial resistance to S. typhimurium (thereby benefiting the pathogen rather than the host), through upregulation of the SPI-2 genes and subsequent outer membrane modification.