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dc.contributor.authorRoach, Dwayne R.
dc.date.accessioned2012-04-04T16:25:47Z
dc.date.available2012-04-04T16:25:47Z
dc.date.issued2012-04-04
dc.identifier.urihttp://hdl.handle.net/10464/3966
dc.description.abstractIt has been proposed that phages can be used commercially as a biopesticide for the control of fire blight caused by the phytopathogen Erwinia amylovora. The aim of these studies was to investigate two common bacterial resistance mechanisms, lysogeny and exopolysaccharide production and their influence on phage pathogenesis. A multiplex real-time PCR protocol was designed to monitor and quantify Podoviridae and Myoviridae phages. This protocol is compatible with known E. amylovora and Pantoea agglomerans rtPCR primers/probes which allowed simultaneous study of both phage and bacterial targets. Using in vitro positive phage selection, bacteriophage insensitive derivatives were isolated within sensitive populations of E. amylovora. Prophage screening with real-time PCR and mitomycin C induction determined that the insensitive derivatives harboured the temperate Podoviridae phage ΦEaTlOO. Lysogenic conversion resulted in resistance to secondary homologous phage infections. Prophage screening of environmental samples of E. amylovora and P. agglomerans collected from various locations in Canada, United States and Europe did not demonstrate lysogeny. Therefore, lysogeny is rare or absent while these bacterial species reside on the plant. Recombineering was used to construct exopolysaccharide deficient E. amylovora mutants. The EPS amylovoran mutants became resistant to Podoviridae and certain Siphoviridae phages. Increasing amylovoran production increased phage population growth, presumably by increasing the total number of bacterial cell surface receptors which promoted increased phage infections. In contrast, amylovoran did not playa role in Myoviridae infections, nor did production of the EPS levan for any phage pathogenesis.en_US
dc.subjectErwinia amylovora -- Biological controlen_US
dc.subjectBacteriophagesen_US
dc.subjectLysogenyen_US
dc.titleErwinia amylovora bacteriophage resistanceen_US
dc.degree.namePh.D. Biological Sciencesen_US
dc.degree.levelDoctoralen_US
dc.contributor.departmentDepartment of Biological Sciencesen_US
dc.degree.disciplineFaculty of Mathematics and Scienceen_US


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