Survivial Strategies in Bacterial Range Expansions

Bacterial communities represent complex and dynamic ecological~systems. Different environmental conditions as well~as bacterial~interactions determine the establishment and sustainability of bacterial diversity. In~this talk we discuss the~competition of three Escherichia coli~strains during range expansions on agar plates. In this bacterial model~system, a~colicin E2 producing strain C competes with a colicin~resistant strain R and with a colicin sensitive strain S for new~territory. Genetic engineering allows us to tune the growth rates of the~strains and to study distinct ecological scenarios.~These scenarios may~lead to either single-strain dominance, pairwise coexistence, or to the coexistence of~all three~strains. In order to elucidate the survival mechanisms of the~individual strains, we also developed a stochastic agent-based model to~capture the ecological scenarios in silico. In a combined theoretical and~experimental approach we are~able to show that the level of~biodiversity depends crucially on the composition of the inoculum, on~the relative growth~rates of the three strains, and on the effective reach~of colicin toxicity.