Berlin 2012 – scientific programme

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BP: Fachverband Biologische Physik

BP 11: Focus: Statistics of Cellular Motion (with DY)

BP 11.10: Talk

Tuesday, March 27, 2012, 13:00–13:15, H 1028

Hydrodynamic Simulation of Bacteria Swimming — •Shang Yik Reigh, Roland G. Winkler, and Gerhard Gompper — Theoretical Soft Matter and Biophysics, Institute of Complex Systems and Institute for Advanced Simulation, Forschungszentrum Juelich, 52425 Juelich

Locomotion of bacteria such as E. coli or Salmonella is achieved by rotation of helical flagella, which are randomly distributed on the cell body. A directional running motion is attained by bundle formation of multiple flagella, while tumbling motion is achieved by the reverse rotation of one of the flagella. Alternating running and tumbling phases allow the bacteria to perform a directed random walk, and play an important role in their chemotaxis. During bacterial swimming, the pitch and the radius of flagella are changed (polymorphic transformations) and the cell body counter-rotates against the flagella to conserve angular momentum. To gain insight into the bacterial swimming behavior, hybrid mesoscale simulations are performed, which combine molecular dynamics simulations for the bacterium with the multiparticle collision (MPC) method for the solvent. The flagella are constructed by a sequence of mass points interacting by bond, bending, and torsional potentials. Such a model can efficiently be coupled to the MPC fluids. Results are presented for the synchronization and the bundle formation of several flagella. The synchronization and bundling times are analyzed in terms of the applied torque, the separation distances, and the number of flagella. The role of counter-rotating cell body for synchronization and bundling will be discussed.