Flagellated bacteria swim by rotating one or several flagella; motility alone results in a random walk, but the flagella’s rotation can be influenced by an intracellular sensory system that enables cells to climb or descend chemical gradients, in a process called chemotaxis. Altogether, motility and chemotaxis allow bacteria to navigate their environment, a critical ability from the level of host-pathogen interactions to geochemical fluxes.

While navigation abilities have been studied extensively in liquid for E. coli, much less attention has been devoted to the diversity of bacteria with different flagella, or to motility in viscous or porous environments that more closely mimic the complexity of natural habitats.

During this seminar, I will present a simple yet powerful chemotaxis assay that I developed in the Taute Lab, combining a recent high-throughput 3D tracking method with microfluidically created chemical gradients. We can directly quantify how well a population of bacteria climbs a gradient, in diverse environments, while simultaneously resolving individual 3D motility behaviors. This assay therefore enables an unprecedented access to a mechanistic understanding and quantitative comparison of navigation strategies. I will highlight its use in various projects, interrogating how different bacteria navigate different environments.

Finally, I will delve into my broader research interest, where I see such an assay as a first step into a multiscale understanding of bacterial pathogens navigation in the human host during early infection processes.