Heterogeneous dispersion of individual bacteria in micropillar arrays

Transport through complex environments is paramount to microorganism propagation and survival. At the scale of a single bacterium, there can be environmental physical features that dramatically alter transport properties at the population level. In this work, we study the transportation of individual bacteria, here Escherichia coli (E. coli), through a lattice of micropillars which serve as structured obstacles with well-defined geometries. To fully account for single cell kinematics, we employ a 4D (3D+time) tracking microscope while imaging in the micropillar environment. Interestingly, we found that the micropillar arrays promote the dispersal of bacteria rather than serving as simple obstacles. We explore the mechanisms of such enhanced transport by studying the spatial dependence of the run-and-tumble statistics of E. coli, in part due to the hydrodynamic interactions between the bacteria and solid surfaces.