Close-range microbial interactions and how they shape a developing colony Microbes live in densely populated and ecologically mixed communities. The spatially structured nature of these communities mean that close-range interactions - social, chemical or mechanical - are important for shaping its development. Using individual-based simulations and experiments we show how spatial structure is essential for the survival of cooperators in the presence of cheaters in a cross-feeding consortium. Our simulations revealed the time it takes for cooperators to meet to be the most accurate predictor of cooperator success. We then went on to show how this could be due to different mixing dynamics in mutual cooperation and one-way interactions, causing cheaters to isolate themselves in a surface-attached setting. This provides a simple and generalizable framework for understanding and designing cooperative interactions in microbial communities as well as teaching us about the benefits of reciprocity. This article was published on Tuesday 3 November 2026
