Interactions between envelope stress responses, bacteriophages and the environment

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Like animals and plants, bacteria are subject to viral infections. Bacterial viruses are called bacteriophages and they are thought to inhabit all environments on Earth in concentrations much higher than those of the bacteria they infect. One reason for this is that a type of bacterial viruses called temperate bacteriophages can infect bacteria and integrate into their chromosomes, where they can live quiescently for many generations before becoming active again. Most bacteria are thought to contain temperate bacteriophages in their genomes. The liberation of temperate bacteriophages from the bacterial chromosome results in the production of many new viruses and the infection and killing of neighbouring susceptible microbes, thus providing a competitive advantage to bacterial populations harbouring such viruses. This is important, since most bacteria live in surface-associated communities with many other microbes where they compete for space and resources and are exposed to environmental stressors that threaten their livelihoods. This is true for Escherichia coli, an inhabitant of the large intestine of animals. En route to, and within the intestine, E. coli must withstand many potentially lethal conditions, including toxic antimicrobial substances produced by our bodies and bacteriophages produced by resident commensal microbes. In order to survive, E. coli uses multiple envelope stress responses to detect and respond to these potentially lethal substances. I hypothesize that bacterial envelope stress responses are sensitive to bacteriophage and that they alter the microbial cell in ways that impact the course of bacteriophage infection and/or the ability to survive stress. I further predict that bacteriophages interact with and alter the E. coli envelope and its genetic network to impact stress adaptive functions. My lab discovered and characterized a new temperate bacteriophage called Kapi1 in a recently isolated "wild" strain of E. coli from a mouse digestive tract. We will use our expertise in bacterial genetics and the study of envelope stress responses to initiate a new research program to investigate how bacteriophages and bacteria interact with each other to influence microbial fitness and stress adaptation. Our work will inform future efforts to control and harness bacteria in the environment, for industrial use, and to improve human and animal health.