Date of Award

Spring 5-14-2023

Document Type

Thesis

Department

Biology

First Advisor

Elizabeth Danka

Second Advisor

David Hunnicutt

Third Advisor

Ryan King

Abstract

Burkholderia cepacia is a gram-negative bacterium first characterized as the causative agent of sour skin in onion crops. More recently, B. cepacia has become a clinical concern as an opportunistic pathogen that can colonize the upper respiratory tract of cystic fibrosis patients and increase mortality in these patients. Infection is exacerbated by the intrinsic resistance to antibiotics found in this genus of organisms. Additional virulence factors help the bacteria persist in the host during infection. However, few of these factors have been described. In this work, we characterized a putative virulence factor that was first identified through an onion infection forward-genetic screen. A mutation in the rfbB gene led to structural differences in the lipopolysaccharide composition, specifically in the O-antigen subunit. While this mutation does not affect normal growth in nutrient-rich media, we demonstrate that biofilm formation and adhesion to the 5637 human epithelial cell line are reduced, leading to diminished virulence. Further characterization of this mutant, among others, aims to better understand necessary virulence factors and the mechanisms required for pathogenicity in both plant and human hosts.

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