Fig. 4: A-motile cells drive collective cell movement along trails.

a Example of scout cells (red line) traveling away from an E. coli island (bright field) followed by swarms (purple lines). b–d Trail maps of scout (left) and swarm (middle) cells and similarity index map (right) for wild type (b), A-S+ (c), and A+S- cells (d). Yellow lines delimitate the predation front. Scalebars = 100 µm. Scalebars of zoomed areas = 20 µm. e Histogram of the length of overlapping tracks (Similarity track length) for wild type, A-S+ and A+S-. Shaded areas highlight the standard deviations from the mean (solid line) of six experimental replicates for the wild-type and four replicates for each mutant strains (see Fig. S4d for single replicate examples). f–h Overlays of all trajectories for wild type (f), S-motile (A-S+) cells (g), and A-motile (A+S-) cells (h) color-coded by time. Green arrows indicate the predation direction, yellow lines delimitate the predation front. White arrows in the zoom of the boxed areas point to examples of trails. i Histogram of movement directionality of swarm cell classes for wild type, A-motile (A+S-) and S-motile (A-S+) communities with directionality lower than 1 being confined motion, equal to 1 being Brownian motion and higher than 1 being directed motion. Shaded areas highlight the standard deviations from the mean (solid line) of six experimental replicates for the wild type and four replicates for each mutant strains (see Fig. S4h for single replicate examples).