A numerical model of Vibrio fischeri growth and intraspecific competition

E. scolopes squids are colonized with V. fischeri bacteria, and this symbiosis serves as a model system for studying host-microbe interactions. Wild-caught adult squids harbor multiple strains of V. fischeri that engage in intraspecific competition during initial host colonization. However, little is known about how competing strains interact at the single-cell level to influence their spatial structure as they coexist. When grown on agar surfaces, two competing strains form segregated spatial patterns that is dependent on their ability to kill one another. We developed an experimentally informed, multi-agent numerical model of cell growth, division, and death in 2D that can simulate intercellular interactions and environmental factors. In particular, the model accounts for intraspecific competition via mutual killing and differences in growth. This computational model is used to explore conditions that allow a diversity of strains to coexist, as well as investigate the spatiotemporal properties of this coexistence. We present results that demonstrate the method’s ability to capture the segregated patterns and their length scales, and explore parameter space that is hard to access in experiments.