Formation, collective motion, and merging of macroscopic bacterial aggregates
Fig 6
Computational Model: Spatial Structure and Merging.
A)- D) Spatial Structure of Aggregates. (A) The simulated spot area distribution has an average of 0.97mm2and a standard deviation of 0.38 mm2. (B) The simulated nearest neighbor distribution has an average of 3.30mm and a standard deviation of 2.49 mm. (C) The spatial correlation function of the simulated aggregates mirrors the saturation of the experimental structure, with saturation to 1 at 3.50 mm. (D) Snapshots before (T = 5.0 h) and after (T = 46.5 h) the merging of two segmented aggregates (see Materials and Methods for segmentation details). E)-H) Merging dynamics in the simulations. (E) Relative distance vs. time for all merging processes, color coded with total aggregate area. (F) The acceleration is not found to be correlated with aggregate size (spearman’s rho 0.01 and a p-value of 0.962). (G) Distribution of aggregate speed for two-spot mergers and non-merging spots. The average (shown by a dashed line) illustrates that mergers, on average, move faster. The speeds of the simulated aggregates are on the same order of magnitude as found in the experiments. (H) Distribution of the ratio of trajectory distance divided by displacement for two-spot mergers and non-merging spots. On average, the paths taken by spots that merge are more direct. Non-merging spots follow a less direct path as compared to the experiments.