Modeling branching and chiral colonial patterning of lubricating bacteria

TL;DR

This paper explores how lubricating bacteria develop complex branching and chiral patterns through communication and cooperative behavior, using generic models to reveal survival strategies and the influence of chemotactic signaling.

Contribution

It introduces a new model of chiral growth incorporating chemotactic signaling and a measure for weak chirality, linking micro-level interactions to macro-level pattern formation.

Findings

Communication leads to self-organization of bacterial colonies.

Chiral growth patterns are influenced by chemotactic signaling.

Model simulations align with experimental observations of bacterial patterns.

Abstract

In nature, microorganisms must often cope with hostile environmental conditions. To do so they have developed sophisticated cooperative behavior and intricate communication capabilities, such as: direct cell-cell physical interactions via extra-membrane polymers, collective production of extracellular "wetting" fluid for movement on hard surfaces, long range chemical signaling such as quorum sensing and chemotactic (bias of movement according to gradient of chemical agent) signaling, collective activation and deactivation of genes and even exchange of genetic material. Utilizing these capabilities, the colonies develop complex spatio-temporal patterns in response to adverse growth conditions. We present a wealth of branching and chiral patterns formed during colonial development of lubricating bacteria (bacteria which produce a wetting layer of fluid for their movement). Invoking ideas from pattern formation in non-living systems and using ``generic'' modeling we are able to reveal novel survival strategies which account for the salient features of the evolved patterns. Using the models, we demonstrate how communication leads to self-organization via cooperative behavior of the cells. In this regard, pattern formation in microorganisms can be viewed as the result of the exchange of information between the micro-level (the individual cells) and the macro-level (the colony). We mainly review known results, but include a new model of chiral growth, which enables us to study the effect of chemotactic signaling on the chiral growth. We also introduce a measure for weak chirality and use this measure to compare the results of model simulations with experimental observations.