Transition of global motion modes in bacterial active solids controlled by bacterial activity

Transition of global motion modes in bacterial active solids controlled by bacterial activity. A circular disk-shaped bacterial active solid derived from early-stage P. mirabilis biofilms was initially undergoing global oscillatory translation. Stating from T = 50 s, it was continuously illuminated by 406 nm violet light and as the cell activity was decreased by violet light, the motion of the bacterial active solid transited to oscillatory rotation mode. The entire field of view is located at the centre of the biofilm. This phase-contrast video is played at 50 frames per second with the real elapsed time indicated in the time stamp. The activity (that is, the average collective speed) of the active solid is shown below the time stamp. Scale bar, 200 μm. See: Xu et al., Nature Physics 19, 46–51 (2023).