| dc.description.abstract | Swarming bacteria, migrating on the solid surface with lateral flagella, show collective motion and fluid-like behavior. In the swarming bacteria motility, diffusion becomes a main process to deliver cargoes like chemicals or nutrients. Here, we investigate the dynamics of passive tracers in the swarming Vibrio alginolyticus bath, because Vibrio alginolyticus has the particular properties such as the snake-like morphology, and forward and backward motion.
In this work, we build up a two-dimensional swarming Vibrio alginolyticus bath with 1 μm polystyrene beads. From the trajectories of polystyrene beads, we calculate
the mean squared displacement (MSD) and the probability density function (PDF) of the displacement of a single particle at the given time lag. The MSD and PDF reveal that the swarming bath is the source of two noises on passive tracers. One type of the noises, the linear motion, has long persistence length but short correlation time, and the other, the fluctuating motion, has short persistence length
but long correlation time. We model this phenomenon as two combined Ornstein-Uhlenbeck process. Finally, by comparing the particle direction to the averaged long-axis direction of neighbor bacteria, we find that the linear motion is resulted from the direct pushing by the spatially well-aligned bacteria and the fluctuating motion is due to the random orientation of bacteria. | en_US |