Topological transition in filamentous cyanobacteria: from motion to structure

TL;DR

This study explores how motility influences pattern formation in filamentous cyanobacteria colonies, revealing a topological transition driven by physical parameters and providing insights into biofilm development.

Contribution

It introduces a model that links motility, interaction strength, and topological transitions in cyanobacteria colonies, capturing both transient and steady-state dynamics.

Findings

Peclet number and interaction strength control topological transition

Structural correlations reveal early biofilm formation stages

Filament length effects are distinct from point-like interactions

Abstract

Many active systems are capable of forming intriguing patterns at scales significantly larger than the size of their individual constituents. Cyanobacteria are one of the most ancient and important phyla of organisms that has allowed the evolution of more complex life forms. Despite its importance, the role of motility on the pattern formation of their colonies is not understood. Here, we investigate the large-scale collective effects and rich dynamics of gliding filamentous cyanobacteria colonies, while still retaining information about the individual constituents' dynamics and their interactions. We investigate both the colony's transient and steady-state dynamics and find good agreement with experiments. We furthermore show that the Peclet number and aligning interaction strength govern the system's topological transition from an isotropic distribution to a state of large-scale reticulate patterns. Although the system is topologically non-trivial, the parallel and perpendicular pair correlation functions provide structural information about the colony, and thus can be used to extract information about the early stages of biofilm formation. Finally, we find that the effects of the filaments' length cannot be reduced to a system of interacting points. Our model proves to reproduce both cyanobacteria colonies and systems of biofilaments where curvature is transported by motility.