Emergent pattern formation in an interstitial biofilm

TL;DR

This study uses an individual-based model to show how substratum stiffness influences pattern formation in interstitial biofilms, revealing environmental conditions can induce organized bacterial structures with potential fitness benefits.

Contribution

The paper demonstrates that substratum stiffness controls emergent pattern formation in biofilms, highlighting environmental influence on bacterial self-organization.

Findings

Substratum stiffness affects biofilm pattern morphology.

Subtle environmental changes induce highly ordered bacterial arrangements.

Ordered patterns may confer fitness advantages.

Abstract

Collective behavior of bacterial colonies plays critical roles in adaptability, survivability, biofilm expansion and infection. We employ an individual-based model of an interstitial biofilm to study emergent pattern formation based on the assumptions that rod-shaped bacteria furrow through a viscous environment, and excrete extracellular polymeric substances which bias their rate of motion. Because the bacteria furrow through their environment, the substratum stiffness is a key control parameter behind the formation of distinct morphological patterns. By systematically varying this property (which we quantify with a stiffness coefficient {\gamma}), we show that subtle changes in the substratum stiffness can give rise to a stable state characterized by a high degree of local order and long-range pattern formation. The ordered state exhibits characteristics typically associated with bacterial fitness advantages, even though it is induced by changes in environmental conditions rather than changes in biological parameters. Our findings are applicable to broad range of biofilms and provide insights into the relationship between bacterial movement and their environment, and basic mechanisms behind self-organization of biophysical systems.