Vahid Nourian | Applied Math, University of Waterloo
Modeling of monotrichous and peritrichous bacterial locomotion in a viscous fluid
Many types of bacteria use flexible thin filaments attached to the cell body and driven by independent rotary motors to induce locomotion. In monotrichous (uni-flagellar) bacteria, a relatively flexible hook transmits the motor torque to the filament. Despite their simple mechanism, they exhibit both straight and also more complex curved trajectories. Many types of peritrichous (multi-flagellar) bacteria (such as E. coli) have different swimming mechanisms in which very flexible hooks allow the flagella to come closer together and form a helical bundle. A rotating bundle generates a propulsive force which pushes the swimmer on a relatively straight trajectory. By mathematical modeling and numerical simulations, we analyze the motion of the both monotrichous and peritrichous bacteria in bulk fluid and near a solid surface. A combination of boundary integral technique and Kirchhoff rod theory can be employed to calculate the hydrodynamic and elastic forces/torques on the cell body and also the flexible hook/flagella. The model can be used to determine the behavior of the bacteria near a particle, a solid surface or other micro-swimmers and also understand more details about the bundling and tumbling process in the peritrichous bacteria. This study can not only lead to the understanding of differences in the bacterial morphology but also contribute to the design of artificial micro-swimmers.