Pattern formation by bacteria-phage interactions

Spatially structured environments strongly impact the coexistence and evolutionary dynamics of bacteria and phage—viruses that infect bacteria—resulting in prolonged co-evolutionary cycles and rich spatio-temporal dynamics; however, the mechanisms underlying such dynamics remain largely unexplored. To address this gap of knowledge, we study a two-dimensional spatial model of motile, growing bacteria that aggregate via motility-induced phase separation (MIPS) and phage that infect and lyse the bacteria. We find that bacteria-phage non-reciprocal predator-prey interactions have a strong impact on MIPS. In particular, the presence of phage can limit bacterial aggregation, giving rise instead to a broad range of finite-scale static and dynamic patterns in which bacteria and phage coexist. This study may provide insights into the spatio-temporal organization of bacteria and phage in structured environments, as well as into a broader range of self-organized active and living systems whose constituents exhibit predator-prey or other non-reciprocal interactions.