Motility deactivation causes dissolution of vortex lattice pattern

Motility deactivation causes dissolution of vortex lattice pattern in quasi-2D dense active fluids comprising S. marcescens. Left, phase-contrast video. Middle, spatial distribution of instantaneous collective velocity associated with the phase-contrast video. Arrows represent velocity direction; the colour map at right indicates velocity magnitude (μm s−1). Right, spatial distribution of instantaneous vorticity associated with the phase-contrast video and plotted in the same manner as for the right panel of Supplementary Video 1. The vortex lattice was illuminated by violet light at T = 35.5 s, and the motility of all cells in the entire field of view was suppressed by violet light illumination (Extended Data Fig. 5). This video is played at 50 frames s−1 with real elapsed time indicated in the time stamp. All panels share the same scale bar, 200 μm. See: Xu et al., Nature 627, 553–558 (2024).