Self-organization of bacterial colonies through quorum sensing and motility regulation

Equilibrium statistical mechanics predicts how the self-assembly of a passive material emerges from the competition between energy and entropy. Out of equilibrium, no such principle applies and generic self-organization mechanisms are scarce. In this talk I will discuss how the regulation of motility allows bacterial colonies to self-organize in space and time. I will show how reciprocal control may lead to static phase separation with colocalization or demixing between competing strains [1], but also how non-reciprocal interactions may lead to travelling waves and dynamic patterns. For a precise type of reciprocal interactions, I will show that bacterial mixtures can be mapped onto passive colloidal systems. This mapping shows that passive self-assembly is embedded into the phenomenology accessible to bacterial suspensions. It also provides powerful principles to account for---and control---the organization of bacterial ecosystems.

[1] A. I. Curatolo, N. Zhou, Y. Zhao, C. Liu, A. Daerr, J. Tailleur, J.-D. Huang, "Cooperative pattern formation in multi-species bacterial colonies", Nature Physics 16, 1152-1157 (2020)