Crop Systems Engineering Seminar Event

Abstract: Many microorganisms live in dynamic fluid environments, yet the impact of flow on microbial ecology often remains unresolved. In this talk, I present laboratory experiments and mathematical models that illustrate how hydrodynamics shape the ecology of bacteria that colonize porous substrates. When we inoculate bacterial cells into patterned microfluidic devices that simulate soil, they form biofilm patches that undergo a self-organization mediated by the interaction of growth and flow. At intermediate flow rates this interaction triggers the formation of preferential flow channels, which severely limit biofilm productivity.  A simple network model, which captures the underlying physics, corroborates our experimental results.  We then use this system to determine how porous media flow impacts the competition between bacterial genotypes that grow at different rates. Using game theory, we predict that porous environments select for bacteria with an ‘evolutionarily stable' growth rate, which outcompete cells that grow either more quickly or more slowly. Our findings stand in sharp contrast to the commonly held assumption that a bacterial genotype's fitness increases monotonically with its intrinsic growth rate.