Orientation field model for chiral branching growth of bacterial colonies

TL;DR

This paper introduces a reaction-diffusion model incorporating bacterial orientation to simulate chiral branching and tip-splitting growth in bacterial colonies, capturing complex morphological transitions.

Contribution

The model uniquely combines a density field with an orientation scalar to reproduce chiral and tip-splitting growth patterns in bacterial colonies.

Findings

Reproduces chiral branching and tip-splitting growth.

Captures morphological transitions between different growth modes.

Applicable to various bacterial strains with different lengths.

Abstract

We present a new reaction-diffusion model for chiral branching growth of colonies of the bacteria Paenibacillus dendritiformis. In our model the bacteria are represented by a density field with non-linear diffusion and a complex scalar field which represents bacterial orientation. The orientation field introduces anisotropy into the flux of bacteria, representing self-propulsion along their long axes. The model can also reproduce tip-splitting growth of other strains (shorter bacteria) of the same species. The model can capture changes of small number of bacteria, thus it can be used to study the open question of transitions between tip-splitting and chiral dendritic growth.