To visualize the bacteria, we used an E. coli MG1655 strain that constitutively expresses the gene for green fluorescent protein mNeonGreen. The gene was inserted into the ydgH gene locus of the chromosome resulting in strain bBPL227. We examined fluorescent E. coli cells under a fluorescence microscope with 470/40nm excitation and 525/50nm emission bandpass filters. To prepare bacteria for experiments, 3 mL of Lysogeny Broth (LB) (Becton Dickinson) was inoculated with bBPL227 from a cryostock and grown overnight in a shaking incubator (Multitron Pro, INFORS HT) at 37 • C and 200 rpm, until the culture reached the stationary phase. We added glycerol to a final concentration of 15% (vol/vol), split the culture into 100 µL aliquots and stored them at -80 • C. For each experiment, an aliquot of stock solution was thawed and transferred to 25 mL LB in a 250 mL Erlenmeyer flask and incubated in a shaking incubator at 37 • C and 200 rpm. The cell culture was grown for 2 -3 hours until mid-exponential phase (typically at an optical density at 600 nm of 0.5). The cells are then harvested and put onto ice for the experiments.