Date of Award

Summer 2019

Degree Type

Masters Thesis

Degree Name

Master of Science (MS)

School

Biological, Environmental, and Earth Sciences

Committee Chair

Dmitri Mavrodi

Committee Chair School

Biological, Environmental, and Earth Sciences

Committee Member 2

Janet Donaldson

Committee Member 2 School

Biological, Environmental, and Earth Sciences

Committee Member 3

Mohamed Elasri

Committee Member 3 School

Biological, Environmental, and Earth Sciences

Abstract

Burkholderia encompass a group of ubiquitous Gram-negative bacteria that include numerous saprophytes, as well as several species that cause infections in animals, immunocompromised patients, and plants. Some species of Burkholderia produce colored redox-active secondary metabolites called phenazines (Phz). In the model opportunistic pathogen Pseudomonas aeruginosa, phenazines strongly contribute to the competitiveness, formation of biofilms, and virulence in multiple models of infection. Similar depth of knowledge on the diversity, biosynthesis, and biological functions of phenazines in Burkholderiais missing. This project aimed to bridge this gap in knowledge by focusing on phenazine pathways of B. lata and closely related species. My results revealed that phzgenes are present in genomes of many Burkholderiathat have a worldwide origin and belong to different species of the genus. Most Phz+ strains were in the Bcc group, but the capacity to synthesize phenazines was also found in some isolates of the B. pseudomalleiclade and the plant pathogen B. glumae. My findings also suggest that the phenazine biosynthetic pathway of Burkholderiahas a complex evolutionary history, which likely involved horizontal gene transfers among several distantly related groups of producing organisms. I also analyzed isogenic mutants and plasmid deletion derivatives of Burkholderia lata, which helped to identify phenazines produced by species of the ubiquitous B. cepacia(Bcc) group and characterize the role of phenazine-modifying genes in the synthesis of 4,9-dihydroxyphenazine-1,6-dicarboxylic acid dimethylester.My functional studies failed to link the production of phenazines with the capacity of Burkholderiato kill fruit flies and rot onions, but other experiments revealed a link between the presence and amount of phenazines and the dynamics of biofilm growth flow in the flow cell and static experimental systems.

Available for download on Sunday, August 01, 2021

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