Motility of \textit{Escherichia coli} in a quasi-two-dimensional porous medium

TL;DR

This study investigates how extit{E. coli} bacteria move in a simulated quasi-2D porous environment, analyzing their trajectories and comparing experimental data with a custom random-walk model to understand the effects of pore size on motility.

Contribution

The paper introduces a novel experimental setup for observing bacterial motility in controlled porous media and develops a phenomenological model to interpret the results.

Findings

Increased latex particle concentration reduces bacterial velocity.

Trajectory analysis reveals more frequent turns in denser media.

The random-walk model successfully replicates experimental movement patterns.

Abstract

Bacterial migration through confined spaces is critical for several phenomena like: biofilm formation, bacterial transport in soils, and bacterial therapy against cancer . In the present work, \textit{E. coli} (strain K12-MG1655 WT) motility was characterized by recording and analyzing individual bacterium trajectories in a simulated quasi-2-dimensional porous medium. The porous medium was simulated by enclosing, between slide and cover slip, a bacterial-culture sample mixed with uniform 2.98 $\mu m$ spherical latex particles. The porosity of the medium was controlled by changing the latex particle concentration. By statistically analyzing trajectory parameters like: instantaneous velocity and turn angle, as well as mean squared displacement, we were able to quantify the effects that different latex particle concentrations have upon bacterial motility. To better understand our results, bacterial trajectories were simulated by means of a phenomenological random-walk model (developed ad hoc), and the simulated results were compared with the experimental ones.