Diffusion of magnetotactic bacterium in rotating magnetic field

Swimming trajectory of a magnetotactic bacterium in a rotating magnetic field is a circle. Random reversals of the direction of the bacterium motion induces a random walk of the curvature center of the trajectory. In assumption of the distribution of the switching events according to the Poisson process the diffusion coefficient is calculated in dependence on the frequency of the rotating field and the characteristic time between the switching events. It is confirmed by the numerical simulation of the random walk of the bacterium in the rotating magnetic field.

Research highlights
► Random switching of the flagella leads to diffusion of a bacterium in the field.
► Mean square displacement of the curvature center is proportional to time.
► Diffusion coefficient depends on the period of a rotating field.
► At zero frequency diffusion coefficient is the same as for a tumbling bacterium.