Investigator: Laura Williams, Providence College
Scientific Theme: Molecular Toxicology
Abstract: Predatory bacteria are bacteria that attack and digest other bacteria. For example, the predator Bdellovibrio bacteriovorus invades and digests Gram-negative prey such as Pseudomonas species. Predation has evolved independently multiple times in bacteria, but only a few species of predatory bacteria are well characterized. Pilot studies suggest that these species are effective in control and eradication of pathogenic bacteria such as Salmonella. To develop predatory bacteria as an alternative to antibiotics and to understand the evolution of this parasitic lifestyle, it is essential to investigate both prey range (what bacterial species are targeted as prey?) and predation efficiency (how quickly and effectively are prey are killed?). Additionally, it is important to explore whether these traits can be manipulated by directed evolution in the laboratory to evolve predators that specialize on particular prey species and/or demonstrate more efficient predation. To this end, the proposed project has two specific aims. Aim 1 (Year 1): isolate predatory bacteria from soil and water and characterize prey range and predation efficiency. Candidate prey bacteria will be isolated from sample sites and identified by 16S rRNA gene sequencing. These potential prey will then be used in a double layer agar technique to isolate predatory bacteria. Recovered predators will be tested against the range of possible prey. Predation efficiency will be measured using a luminescence assay, in which prey are transformed with a plasmid carrying lux genes. Aim 2 (Year 2): test evolvability of prey range and predation efficiency using experimental evolution. Selected predatory bacteria isolates from Aim 1 will be grown in the laboratory for hundreds of generations under two conditions: (1) a single prey species or (2) a mix of prey species. Phenotypic changes in prey range and predation efficiency will be assayed using techniques described above. Genotypic changes will be identified by whole genome sequencing. Outcomes of this project will inform our understanding of naturally occurring variation in prey range and predation efficiency and assess the feasibility of developing predatory bacteria as alternatives to antibiotics.
Human Health Relevance: Antibiotic resistance is a serious challenge facing public health, and new strategies to control and eradicate pathogens are desperately needed. Predatory bacteria are bacteria that attack and digest other bacteria, including pathogens. This project investigates the prey range and predation efficiency of different predatory species and explores the feasibility of developing predatory bacteria as alternatives to antibiotics.