Non-equilibrium nucleation in antagonistic microbial communities

Nucleation, the emergence of a new phase within a surrounding medium, is a fundamental process across the physical sciences, but its role in shaping biological systems remains underexplored. This project investigates nucleation in microbial communities where antagonistic interactions, such as toxin production, create ecological analogs of surface tension and energy barriers. These interactions can give rise to critical inoculum sizes below which invading strains fail to establish, a clear signature of nucleation dynamics. By combining mathematical modeling with synthetic microbial ecosystems, the project will study how nucleation barriers and metastable states emerge from microbial interactions. We will examine how the critical inoculum size depends on interaction strength, diffusion, and growth rates, and explore nucleation behavior in communities with more than two antagonistic strains. The work will also incorporate engineered systems that combine antagonism with cross-feeding, enabling controlled exploration of richer, non-classical nucleation dynamics. This project aims to develop microbial nucleation as a tractable model system for studying non-equilibrium phenomena in biology, and to advance mathematical understanding of out-of-equilibrium systems where no underlying free energy function governs the dynamics. The results have the potential to deepen our understanding of ecological pattern formation, stability, and control.