An emergent property of collective migration: spatial organization of motility phenotypes

To invade new territories, groups of bacteria consume and collectively chase nutrients using chemotaxis. Though decades of quantitative studies have elucidated the dynamic of bacterial migration, how non-genetic diversity affects this dynamic is not fully understood. Collective migration requires coordination, but cells within a genetically-homogenous population exhibit diverse motility behaviors. Previous work in our lab demonstrated that how fast bacterial cells climb chemical gradients depends on their swimming phenotypes. As a result, cells are spatially organized based on their chemotactic performances; cells with higher performances lead at the front, where the attractant gradient is low, and cells with lower performances stay at the back, where the attractant gradient is high. While this was demonstrated in liquid, the same principle predicts that spatial organization of phenotypes is different in other environments. Here, we tested this prediction by measuring diffusions, chemotactic performances, and spatial organizations of motility phenotypes in populations that are migrating in porous environments. Our results will demonstrate that populations can leverage non-genetic diversity to migrate through multiple environments by altering their leader-follower structures.