Coevolutionary interactions between bacteria and phage in natural environments

Abstract

Bacteria and their viruses (bacteriophage, phage) are the most abundant and diverse taxonomic groups, but ecological and evolutionary research on bacteria-phage interactions has largely focused on studies of simplified communities using a few model organisms. The goal of the thesis is to understand how bacteria and phage interact within natural environments, and how these interactions impact the patterns of phage infectivity and bacterial resistance. Here I investigate the effects of natural environments on the coevolutionary patterns of bacteria (Pseudomonas fluorescens) and phage (SBW25Φ2). In chapter 3 I investigate the effects of nineteen different communities on the coevolutionary interactions of SBW25 and phage, and the degree to which the infectivity of phage to its host, SBW25, changes depending on their local microbial community. Chapter 4 aimed to understand the effects of varying diversities of communities on coevolutionary interactions. In Chapter 5, I looked at how coevolutionary interactions were affected by different communities in different abiotic conditions (pH, temperature and nutrient concentration) and the effect communities had on the ability of SBW25 to adapt to the abiotic conditions. Understanding how biological and physical factors affect coevolutionary interactions in natural environments allows predictions of how phage and bacteria coevolve in natural and unnatural settings.