Phylogenetic Analysis and Characterization of Plant, Environmental, and Clinical Strains of Pantoea

Nadarasah, Geetanchaly
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Faculty of Graduate Studies and Research, University of Regina

Multihost bacterial pathogens are an increasing concern as more bacterial species are found to cause harm to humans. Pantoea is recognized as a multihost pathogen, colonizing various hosts including plants, insects, and humans; however it is unknown how these strains are related, and the extent of their specific host ranges. Multilocus sequence analysis (MLSA) on six housekeeping genes of Pantoea revealed that some species are mixed, and contain plant, clinical, and environmental strains, while other species groups are composed of only plant or only clinical strains. Comparative growth assays in maize, onion, and fruit flies revealed that all plant, clinical, and environmental strains are capable of colonizing both plant and animal hosts. Pantoea clinical strains had an overall greater growth rate within fruit flies in comparison to either plant hosts. The results of this work have shown that some Pantoea strains have a broad host range, while others are more host specific. The close relationship of plant and environmental strains to clinical strains and their ability to colonize plants and fruit flies with equal efficiency, highlights the potential for these strains to cause human infections. This work also suggests that strains causing human infections likely originate from the general environment.

A Thesis Submitted to the Faculty of Graduate Studies and Research In Partial Fulfillment of the Requirements for the Degree of Master of Science in Biology, University of Regina. ix, 162 l.