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Hamilton Green


Department: Microbe-Host Interaction

Faculty Mentor: Jonathan Schmitz, Ph.D., M.D.

Dissertation Description: Integrating Metabolism, Genetic Plasticity, and Niche-Specific Fitness in Escherichia coli

My current research focus, as a member of the Schmitz and Hadjifrangiskou Lab, is to demonstrate the relationship between in situ bacterial metabolism; genetic plasticity / strain-to-strain diversity; and environment-specific fitness for a microbe that serves as a prominent laboratory model-organism (Escherichia coli), but also a ubiquitous human commensal and frequent opportunistic pathogen. Escherichia coli demonstrates profound genotypic and phenotypic variability between individual strains, as well an ability to populate diverse environmental niches. Work within our laboratory has demonstrated that, when exposed to ambient concentrations of metabolites as they exist within the gut (short-chain fatty acids), E. coli develops loss-of-function mutations of RNA polymerase sigma factor S (rpoS), resulting in bacterial phenotypes that are commonly encountered among wild-type isolates from the bladder. I plan to explore this discovery by implementing techniques or strategies that both survey the wild-type rpoS status of urine-derived E. coli, as well as combine this work with established in vitro and in vivo models to assay their fitness.