Exploring the responses of individual bacteria to micropillar arrays*

Mechanosensing is an emergent field of interests in bacterial studies due to its close relevance to their adaption to natural habitats and many pathogenic processes. Here, we studied the mechanosensing of bacteria to an array of micro-pillars fabricated through photolithography. Using a 3D tracking microscope, we extended the tracking of motile Escherichia coli and captured their individual interactions with multiple pillars. We analyzed the run-and-tumble statistics of E. coli as they interacted with these micro-pillars, which show no significant differences from the non-pillar cases. We also obtained the spatial dependency of the run-and-tumble statistics by mapping the individual bacterial movements in an extended lattice of micro-pillars into a single lattice unit cell. Through this analysis, we have shown that the bacterial movement is highly confined to the proximity near the solid surfaces, suggesting a passive response of E. coli to their mechanical interactions with the micro-pillars.