Comparative Analysis of Flagellotropic Agrobacterium Phages

Abstract

The planetary microbiome is dominated by bacteriophages, the viruses of bacteria. Bacteriophages utilize various means to infect their bacterial hosts, but all phages require receptors on the host surface. Flagellotropic bacteriophages involve an actively rotating bacterial flagellum to attach and initiate the infection process. Flagellotropic bacteriophages are poorly studied compared to their non-flagellotropic counterparts. It is important to research the relationship between these phages and their hosts to elucidate the mechanisms behind the attachment and infection process. It is imperative that we expand the knowledge on these mechanisms due to the increase in potential phage applications both medically and environmentally. This study investigates three flagellotropic phages and their bacterial hosts: Milano and host Agrobacterium tumefaciens str. C58, OLIVR4 and host Agrobacterium Biovar 1 str. ST15.13/040, and 7-7-1 and host Agrobacterium sp. H13-3. Chapter 1 is a literature review. Chapter 2 discusses the identification of the bacterial lipopolysaccharide as a secondary receptor for bacteriophage Milano, and the cross infectivity of the three bacteriophages with the three host bacteria. We quantified infectivity of the three bacterial host strains with the three bacteriophages by performing Efficiency of Plating assays (EOPs) and observed interesting relationships between the phages and host strains. We were also able to further support the hypothesis that OLIVR4, a recently discovered Agrobacterium phage, is indeed flagellotropic by infecting a host mutant with non-rotating flagella with OLIVR4. Overall, this research will help expanding the knowledge of this special class of bacteriophages, opening the door for their further applications in medicine and environmental sciences.