The collective movement of chemotactic bacterial cells along self-generated gradients

Many cell populations actively move depending on environmental conditions which they shape themselves. Populations of chemotactic bacteria, for example, commonly coordinate their movement to reach new nutrient sources. The movement is driven by a combination of flagella-driven propulsion along sensed gradients in nutrient availability and the consumption of nutrients which shape these gradients. I discuss in this talk recent progress in understanding this navigated migration process and the cell-physiological and environmental factors which shape it. First, I present theory and experiments with the model organism E. coli which show how bacterial populations can utilize chemotaxis and substrate consumption to rapidly migrate into nutrient-rich territory. I contrast these migration dynamics to those modeled by the Fisher-Kolmogorov-Petrovsky-Piskunov equation which which do not include chemotaxis and are canonically used to describe the migration of motile organisms into new territories. Second, I discuss how E. coli cells tightly couple the synthesis and activity of their motility machinery with biomass accumulation and cell size to ensure efficient swimming and rapid migration across a wide range of environmental conditions. Third, I outline how E. coli might utilize chemotaxis and navigated migration via self-generated nutrient gradients to thrive within their native habitat of the mammalian intestine. Finally, I argue why the discussed navigated form of migration, enabled by chemotaxis and a strong impact of cells on their local environment, could be ubiquitous and drive the collective movement of many cell types across biological domains.