Public good diffusion limits microbial mutualism

TL;DR

This paper extends game theory to model microbial mutualism mediated by diffusible molecules, revealing that increased sharing can weaken cooperation and cause species extinction, with analytic insights into critical diffusion parameters.

Contribution

It introduces a game-theoretic framework with renormalized parameters to describe microbial interactions via diffusion, uncovering counterintuitive effects of metabolite sharing.

Findings

Greater sharing of metabolites reduces cooperation strength.

Identified critical diffusivity leading to species extinction.

Fitness nonlinearities influence mutualism stability.

Abstract

Standard game theory cannot describe microbial interactions mediated by diffusible molecules. Nevertheless, we show that one can still model microbial dynamics using game theory with parameters renormalized by diffusion. Contrary to expectations, greater sharing of metabolites reduces the strength of cooperation and leads to species extinction via a nonequilibrium phase transition. We report analytic results for the critical diffusivity and the length scale of species intermixing. We also show that fitness nonlinearities suppress mutualism and favor the species producing slower nutrients.