Dynamics of bacteria scanning a porous environment

TL;DR

This paper investigates how bacteria navigate porous environments, revealing that local geometry influences their motion, leading to optimized paths and a significant acceleration of their dynamics, with a transition related to obstacle density and reorientation rate.

Contribution

It introduces a strategy where reorientation suppression or intensification based on local density enhances active particle navigation in disordered media.

Findings

Reorientation behavior varies with local density of obstacles.

Diffusion coefficient shows non-monotonic dependence on tumbling rate.

A localisation transition occurs with increased obstacle density or decreased reorientation rate.

Abstract

It has recently been reported that bacteria, such as E.coli and P. putida, perform distinct modes of motion when placed in porous media as compared to dilute regions or free space. This has led us to suggest an efficient strategy for active particles in a disordered environment: reorientations are suppressed in locally dilute regions and intensified in locally dense ones. Thereby the local geometry determines the optimal path of the active agent and substantially accelerates the dynamics for up to two orders of magnitude. We observe a non-monotonic behavior of the diffusion coefficient in dependence on the tumbling rate and identify a localisation transition, either by increasing the density of obstacles or by decreasing the reorientation rate.