Author ORCID Identifier

https://orcid.org/0000-0001-6939-1351

Date of Award

Spring 5-11-2023

Document Type

Thesis (Ph.D.)

Department or Program

Microbiology and Immunology

First Advisor

Deborah A. Hogan

Second Advisor

Mary Lou Guerinot

Third Advisor

Carey D. Nadell

Abstract

Change is the only constant in life, and these changes, though random in nature, can have consequences. Quorum sensing is heterogeneous in phenotype and prone to negative selection. In P. aeruginosa, the regulator LasR is frequently non-functional in phylogenetically diverse isolates. Through repeated experimental evolution and mathematical modeling, we show that differences in growth enable lasR mutant evolutionary success and this requires a system enabling metabolic choices, known as carbon catabolite repression (or catabolite repression). The differences in catabolite repression between wild type and lasR mutants enable altered metabolite preferences, and the resulting differences in metabolic states enable intraspecies cross-feeding important for strain fitness. Cross-feeding within these clonally-derived populations promotes virulence factor production beyond either strain in isolation. The emergent properties inherent in populations with heterogeneous quorum sensing function likely impact community composition, structure, and function.

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