Effect of microbial community on Salmonella growth
Kwan, Tiffany Wen
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Salmonella is a foodborne pathogen that affects humans worldwide. While the virulence factors of this organism have been well-studied, much less is known about its behavior in a mixed community. The intestinal tract is populated with a diverse microbial community, with which Salmonella must compete. In order to study how Salmonella growth is affected by the presence of naturally-occurring intestinal bacteria, Salmonella Typhimurium was cocultured with Lactobacillus, Eubacterium, and Bacteroides, which represent the two largest bacterial groups (Firmicutes and Bacteroidetes) found in the gastrointestinal tract. An anaerobic in vitro batch system and complex medium that mimics the chicken cecum were developed for this study. Growth rates were calculated for Salmonella and community composition was determined by a combination of traditional culture methods and fluorescence in situ hybridization (FISH). A mathematical model was developed in order to further understanding of the effects of metabolism and interaction on microbial growth dynamics.