Influence of cell-cell distance on the ecology and evolution of microbial communities.

Microorganisms assemble into spatially structured communities in which neighboring cells are separated by highly heterogeneous cell-cell distances. These spatial distances are not merely geometric features but key ecological variables that determine whether cells can exchange metabolites, compete through toxins, sense one another, or transfer genes, thereby profoundly influencing community assembly, productivity, and the evolution of microorganisms residing in communities. In this review, we synthesize recent progress on how cell-cell distance in microbial communities is determined, as well as how it modulates microbial interactions that lead to diverse ecological and evolutionary consequences. Specifically, we propose several testable conceptual frameworks that help quantify complicated distance-interaction relationships. We discuss emerging imaging, automated analysis, and spatial engineering approaches that now make it possible to quantify and manipulate cell-cell distance with increasing precision. Viewing microbial communities through the lens of cell-cell distance provides a unifying framework for linking microscale spatial organization to microbiome function, offering new opportunities to predict and engineer microbial communities.