Movie S1.

Growth of the Rg V. cholerae biofilm cluster from one founder cell to 8,500 cells. Imaging began 1 h after attachment; total duration is 20 h with 30-min time steps. The cluster first expands with a branched morphology, and then increases in cell density. Cells at the center reorient in the vertical direction and ultimately pack parallel to one another. Cross-sectional images of the bottom cell layer are shown. The strain constitutively expresses mKO. The field of view is 46.5 μm × 46.5 μm.