Competition for space during bacterial colonization of a surface

Abstract

Competition for space is ubiquitous in the ecology of both microorganisms and macro-organisms. We introduce a bacterial model system in which the factors influencing competition for space during colonization of an initially empty habitat can be tracked directly. Using fluorescence microscopy, we follow the fate of individual Escherichia coli bacterial cell lineages as they undergo expansion competition (the race to be the first to colonize a previously empty territory), and as they later compete at boundaries between clonal territories. Our experiments are complemented by computer simulations of a lattice-based model. We find that both expansion competition, manifested as differences in individual cell lag times, and boundary competition, manifested as effects of neighbour cell geometry, can play a role in colonization success, particularly when lineages expand exponentially. This work provides a baseline for investigating how ecological interactions affect colonization of space by bacterial populations, and highlights the potential of bacterial model systems for the testing and development of ecological theory.

Microbial expansion-collision dynamics promote cooperation and coexistence on surfaces

“…C and D and S3). This tessellation pattern is consistent with expansion–collision colony dynamics (Lloyd and Allen ), thus supporting the fact that our unshaken experimental treatment is in fact a test of expansion–collision dynamics.…”

“…; Van Dyken et al. ; Lloyd and Allen ). Justification for the generalization of our findings to other surfaces requires future empirical work.…”

“…). Here, we investigate a spatial setting that may be common in nature, but which has yet to be investigated in much detail: surface colonization with colony expansion–collision dynamics (Lloyd and Allen ).…”

“…Most previous work on surface-attached microbial growth from an evolutionary and ecological perspective has focused on a setting where microbes live in densely crowded, genetically heterogeneous cell masses such as biofilms (Nadell et al 2010). Here, we investigate a spatial setting that may be common in nature, but which has yet to be investigated in much detail: surface colonization with colony expansion-collision dynamics (Lloyd and Allen 2015).…”

“…In the boundary competition regime, competition favors genotypes that have higher relative fitness in direct encounters. Lloyd and Allen (2015) previously investigated the dynamics of competition between high and low fitness strains in an expansion-collision setting. They showed that a high-fitness strain increases in frequency by taking over more territorial area than the low fitness strain.…”