Weak synchronization and macroscopic collective oscillation in dense bacterial suspensions

This real time video uncovers a spectacular form of biological collective motion: Millions of motile cells in dense bacterial suspensions can self-organize into highly robust collective oscillatory motion, while individuals move in an erratic manner. The cells seen here were fluorescent, and they were mixed with non-fluorescent cells at a ratio of 1:99. Red trace indicates the trajectory of a cluster consisting of immotile cells that can serve as a flow tracer to reveal the hidden order in bacterial collective motion. See: Chen et al. Nature (2017) doi:10.1038/nature20817.