From run-and-tumble to hopping-and-trapping: Bacterial foraging in porous landscapes

Recent studies using porous environments have elucidated an alternative bacterial foraging strategy to the prototypical run-and-tumble dynamics previously believed to be the sole method of foraging in Escherichia coli. Using this ‘hopping-and trapping’ foraging strategy, E. coli traverses patchy landscapes more efficiently by rapidly exploring various cell-body orientations when trapped, allowing it to exploit narrow corridors and escape confined locations. While believed to be a response to a change in porosity, exactly how the cell recognizes when to transition between these two strategies is still unknown. Additionally, it is unclear whether heightened cell density is perceived as a dynamic porous landscape leading to a foraging switch. In this work we investigate these open-ended questions using porous and patchy microfluidic landscapes. Extensions are made of this framework to Pseudomonas aeruginosa, previously characterized swimming in a ‘run-reverse-pause’ strategy using its single flagellum.