Investigator: Laura Williams, Providence College

Mentor: Christopher Lane, University of Rhode Island

Scientific Theme: Molecular Toxicology

Abstract: The proposed project investigates the arsenal of hydrolytic enzymes produced by predatory bacteria, which are bacteria that attack and digest other bacteria, including animal and plant pathogens. Lytic enzymes play key roles in bacterial cell killing during the predatory life cycle, and they and the predatory bacteria that deploy them constitute a largely unexplored resource for novel biomedical and biotechnological tools. In particular, predatory bacteria and their lytic enzymes are promising alternatives to traditional antibiotic therapies, which are losing effectiveness as antibiotic resistance increases worldwide. Analyzing sequence variation within lytic enzyme gene families and assessing their molecular evolution in response to different selective pressures will inform ongoing development of these molecules as biocontrol agents.

In Aim 1, we will sequence and annotate predatory bacteria genomes from our collection of isolates obtained from different environments in and around Rhode Island. This collection represents three different families of predatory bacteria and provides a broader view of the diversity of lytic enzyme gene content. We will identify and classify genes encoding lytic enzymes and analyze sequence variation within gene families. In Aim 2, we will perform experimental evolution to understand how exposure to particular prey species affects molecular evolution of lytic enzyme genes and overall genome evolution. We will evolve selected predatory bacteria isolates over hundreds of generations in the presence of one prey species or a mix of prey species. Using genome sequencing and phenotype assays, we will reconstruct the evolutionary pathways of evolved lines, identifying stepwise changes in genotype and correlating mutations with changes in prey range and predation efficiency. This aim evaluates the feasibility of directed evolution of specialist predatory bacteria that preferentially attack particular bacterial pathogens. The proposed project will inform development of predatory bacteria and their lytic enzymes as novel tools in healthcare and industry. More broadly, outcomes of this research will contribute to our understanding of the evolutionary trajectories that led to predation as a bacterial lifestyle.

Human Health Relevance: Antibiotic resistance is a serious threat to healthcare, and alternatives to traditional antibiotic therapies are desperately needed. This project investigates the diversity and evolution of lytic enzymes, which play key roles in bacterial cell killing during the life cycle of predatory bacteria. These enzymes and the predatory bacteria that produce them are a promising resource for novel biomedical and biotechnological tools.