"Effect of topographical steps on the surface motility of the bacterium Pseudomonas aeruginosa"
Y-R Chang, ER Weeks, D Barton, J Dobnikar, & WA Ducker, ACS ACS Biomater. Sci. Eng. 5, 6436-6445 (2019).

Bacteria traverse surfaces as part of colonizing solids, and it is of interest to hinder this motion to potentially thwart infections in humans. Here we demonstrate that topographical steps hinder the ability of a particular bacterium, Pseudomonas aeruginosa PAO1 (P. aeruginosa), to traverse a solidliquid interface. Using time-lapse fluorescence microscopy and image analysis, we analyzed the motion of P. aeruginosa that were challenged with steps ranging in height from 0.4 um to 9.0 um. Bacterial motion is sensitive to the height of the step, the curvature of the step face, and the direction of bacterial motion relative to gravity. When the step height is >= 0.9 ┬Ám, which is similar to the cell diameter (~1 um), there is a reduced probability of the cell crossing the step. Of those that do cross, there is a time penalty for crossing steps of height 2~3 um, which is similar to the length of the bacterium. For higher steps, the bacteria reorient their cell body while traversing the step riser. Our findings elucidate how topography influences the motion of bacteria and inform strategies for hindering bacterial motion at surfaces.