Collective Motion and Nonequilibrium Cluster Formation in Colonies of Gliding Bacteria

Fernando Peruani (1) , Joern Starrus (2) , Vladimir Jakovljevic (3) , Lotte Sogaard-Andersen (3) , Andreas Deutsch (2) , Markus Baer (4)

1 LJAD - Laboratoire Jean Alexandre Dieudonné
2 Center for Information Services and High Performance Computing
3 Max Planck Institute for Terrestrial Microbiology
4 PTB

We characterize cell motion in experiments and show that the transition to collective motion in colonies of gliding bacterial cells confined to a monolayer appears through the organization of cells into larger moving clusters. Collective motion by nonequilibrium cluster formation is detected for a critical cell packing fraction around 17%. This transition is characterized by a scale-free power-law cluster-size distribution, with an exponent 0.88±0.07, and the appearance of giant number fluctuations. Our findings are in quantitative agreement with simulations of self-propelled rods. This suggests that the interplay of self-propulsion and the rod shape of bacteria is sufficient to induce collective motion.

Domaines: Biophysique [physics.bio-ph]

Fernando Peruani, Joern Starrus, Vladimir Jakovljevic, Lotte Sogaard-Andersen, Andreas Deutsch, et al.. Collective Motion and Nonequilibrium Cluster Formation in Colonies of Gliding Bacteria. Physical Review Letters, 2012, 108, pp.098102. ⟨10.1103/PhysRevLett.108.098102⟩. ⟨hal-00905217⟩