What determines phage-mediated control of microbial communities?

Objetivo

Bacteriophage (phage) are ubiquitous viruses of microbes that can both rapidly kill their hosts and transfer genes between them. Phage are believed to play a major role in all ecosystems because of their potential to regulate the structure of microbial communities and drive evolutionary innovations. While phage can have a major impact on their microbial hosts, existing experimental and correlational approaches make it unclear if they generally do. Here, we aim to understand when and why phage are major players in shaping natural microbial communities as opposed to passive followers.

Previous work strongly suggests that low community complexity, wet environments that promote motility, and high nutrient conditions will all promote increased phage impacts. However, these impacts may be short-lived as a consequence of bacteria having an advantage during rapid coevolutionary arms races between bacterial resistance and phage infectivity. To balance ecological realism with experimental tractability, we will test these predictions using a unique library of 46 characterised soil bacteria isolates and associated phage in soil. While we aim for our findings to be generalisable, we focus on soil because the role of phage in soil communities is particularly unclear. We will integrate phenotypic, genomic and modelling approaches to follow the ecology and coevolution of these complex communities over many months. We will then use these data to identify ecological signatures of when phage are drivers or followers of microbial ecological dynamics, which we will then quantify in real soil communities.

The project will ultimately shed light on the ecological conditions and temporal and spatial scales under which phage are more or less important in shaping microbial ecology and evolution in natural communities. This knowledge will provide broad insights, ranging from improved predictions of ecosystem responses to environmental change to optimization of phage therapy.