A purely mechanical model with asymmetric features for early morphogenesis of rod-shaped bacteria micro-colony

TL;DR

This paper introduces a purely mechanical, asymmetric model for early bacterial micro-colony morphogenesis, emphasizing non-overlapping constraints and asymmetries in mass and friction to replicate growth behaviors without attraction forces.

Contribution

The model uniquely incorporates asymmetry and non-overlapping constraints, providing a novel approach to simulate micro-colony shape development without relying on attraction interactions.

Findings

Model reproduces micro-colony growth behaviors without attraction forces

Asymmetry influences friction and mass distribution effects

Systematic comparison with experimental data validates the model

Abstract

To model the morphogenesis of rod-shaped bacterial micro-colony, several individual-based models have been proposed in the biophysical literature. When studying the shape of micro-colonies, most models present interaction forces such as attraction or filial link. In this article, we propose a model where the bacteria interact only through non-overlapping constraints. We consider the asymmetry of the bacteria, and its influence on the friction with the substrate. Besides, we consider asymmetry in the mass distribution of the bacteria along their length. These two new modelling assumptions allow us to retrieve mechanical behaviours of micro-colony growth without the need of interaction such as attraction. We compare our model to various sets of experiments, discuss our results, and propose several quantifiers to compare model to data in a systematic way.