Grant: Discovery Grants Program - Individual

Microbial diversity and the roles of bacteria in the function of ecosystems are greatly influenced by interactions with bacteriophages. These interactions can be complex but at the most basic level is the ability of an individual bacteriophage to attack and multiply within a single bacterium. This ability is determined by the bacterial genome encoding components such as surface receptors and several defense systems, and by the bacteriophage genome. The proposed research involves investigation of the genes of bacteriophages that attack the bacterial species, Erwinia amylovora and Pantoea agglomerans, for contributions to host pathogenesis. We have recently sequenced the genomes of nineteen bacteriophages that are individually variable in interaction with several host species. Observed interactions between the bacteriophages and E. amylovora include lysis with progeny production that varies over four orders of magnitude, lysogeny, and pseudolysogeny, or no apparent attack whatsoever. This sequence information is a valuable resource for understanding the genetic control of all of this variation in bacteriophage attack. Specific short term objectives of this research will involve: (1) correlation of bacteriophage genes with variation in host attack and annotation of these genes; (2) co-evolution experiments with repeated passages of the bacteriophages through a specific bacterial host to look/select for altered interaction and to observe any mutational changes in the genes identified in (1); and, (3) to artificially induce mutations in bacteriophages that result in altered interaction with the host and to relate these mutations to the genes identified in (1). Long term objectives will include correlation of host-encoded attributes with these bacteriophage components. The expected significance of the proposed research is that we shall identify various molecular mechanisms of bacteriophage attack and ultimately how all of this observed variation impacts on microbial diversity and population dynamics.