Quantifying interactions in a small bacterial community

Speaker: PI Sara Mitri, Département de Microbiologie Fondamentale (DMF), Université de Lausanne

Host: Associate Professor Mette Burmølle, Section for Microbiology

Abstract
Microbial communities in our guts, on our skin or in our soil are vital to our health and economy. These communities may consist of hundreds of co-existing and interacting species that affect each other’s growth and survival, which may in turn affect the functioning of the community as a whole. Because monitoring and understanding population dynamics within these communities is extremely challenging, we prefer to first start by disentangling interactions in smaller and simpler ecosystems. To this end, we have recently developed a model system consisting of four bacterial species that were combined due to their ability to degrade pollutants in industrial waste water. Our first analysis of this simple ecosystem has shown that these species can co-exist in a stable manner, and that all four species grow better in the presence of at least one other member of the community compared to alone. Interestingly, preliminary data suggest that these interactions are context-dependent: adding in rich nutrient sources decreases positive interactions between them. In this talk, I will address the experimental and theoretical approaches we are developing to identify and compare different interactions, and the challenges associated with them. I will also present data regarding how these effects change in a spatial setting with the four species growing on agar surfaces.