Speaker
Description
The immense diversity observed in natural microbial communities is surprising in light of the competitive exclusion principle and the numerous weapons microbes have evolved to inhibit each other's growth. In this work, we study patterns of antibiotic-mediated interactions between microbes using classical models from theoretical ecology. Building on previous work, we analyse the ecological dynamics induced by a wide range of interaction patterns that involve antibiotic production, resistance, and degradation. For some simple cases, we give exact rules for the strain phenotypes required for the existence of a stable, steady-state of the community dynamics. Sufficient conditions are obtained for more complex cases limited by computational power. These results agree with and strengthen an observation that has already been made in previous studies of similar systems - a particular producer-sensitive-degrader (PSD) motif is potentially important for community stability. As an extension of these rules to structured populations, we also analyse in greater detail the simplest instance of the PSD motif - a pattern that gives rise to an unstable community in a well-mixed setting. Using individual-based simulations, we show robust co-existence for a large range of values of the diffusivities of the antibiotic and degrader molecules, explicitly showing the effect of spatial structure. In summary, this work extends our understanding of which (and how) patterns of biotic interactions are essential for stability in both structured and unstructured microbial communities.
