Mechanically-driven spreading of bacterial populations

TL;DR

This study models how mechanical interactions, specifically cell exclusion effects, influence the spreading speed of bacterial populations, revealing that physical cell interactions can significantly accelerate population expansion.

Contribution

It introduces a continuum-mechanics model incorporating cell exclusion effects to explain bacterial spreading dynamics, highlighting the role of mechanical interactions in population propagation.

Findings

Exclusion effects increase front propagation speed.

Cell packing fraction influences spreading dynamics.

Model aligns qualitatively with experimental observations.

Abstract

The effect of mechanical interactions between cells in the spreading of bacterial populations was investigated in one-dimensional space. A continuum-mechanics approach, comprising cell migration, proliferation, and exclusion processes, was employed to elucidate the dynamics. The consequent nonlinear reaction-diffusion-like equation describes the constitution dynamics of a bacterial population. In this model, bacterial cells were treated as rod-like particles that interact with each other through hard-core repulsion, which introduces the exclusion effect that causes bacterial populations to migrate quickly and at high density. The propagation of bacterial density as a traveling wave front over extended times was also analysed. The analytical and numerical solutions revealed that the front speed was enhanced by the exclusion process, which depended upon the cell-packing fraction. Finally, we qualitatively compared our theoretical results with experimental evidence.