Emergence of active nematics in bacterial biofilms

Abstract

Growing tissue and bacterial colonies are active matter systems where cell divisions and cellular motion generate active stress. Although they operate in the non-equilibrium regime, these biological systems can form large-scale ordered structures such as nematically aligned cells, topological defects, and fingerings. Mechanical instabilities also play an essential role during growth by generating large structural folding. How active matter dynamics and mechanical instabilities together develop large-scale order in growing tissue is not well understood. Here, we use chain forming Bacillus subtilis, also known as a biofilm, to study the direct relation between active stress and nematic ordering. We find that a bacterial biofilm has intrinsic length scales above which series of mechanical instabilities occur. Localized stress and friction control both linear buckling and edge instabilities. Remarkably, these instabilities develop nematically aligned cellular structures and create pairs of motile and stationary topological defects. We also observe that stress distribution across the biofilm strongly depends on the defect dynamics which can further initiate the formation of sporulation sites by creating three-dimensional structures. By investigating the development of bacterial biofilms and their mechanical instabilities we are proposing a new type of active matter system which provides a unique platform to study the essential roles of nematics in growing biological tissue.

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Cited by in corpus (30)

• Topological active matter
• Topological defects promote layer formation in Myxococcus xanthus colonies
• Self-organized dynamics and the transition to turbulence of confined active nematics
• The physics of active polymers and filaments
• Bacteria solve the problem of crowding by moving slowly
• Hydrodynamics of Active Defects: from order to chaos to defect ordering
• Morphology of active deformable 3D droplets
• Large-scale orientational order in bacterial colonies during inward growth
• Trade-offs in phenotypic noise synchronize emergent topology to actively enhance transport in microbial environments
• Microbial Active Matter: A Topological Framework
• Fingering Instability of Active Nematic Droplets
• Controlling topological defects and contractile flow in confined nematic cell population
• Exact coherent structures and phase space geometry of pre-turbulent 2D active nematic channel flow
• Phase Separation Driven by Active Flows
• Tilt-induced polar order and topological defects in growing bacterial populations
• Alignment of a topological defect by an activity gradient
• Binding self-propelled topological defects in active turbulence
• Microdomains and Stress Distributions in Bacterial Monolayers on Curved Interfaces
• Active nematics with quenched disorder
• Phase behaviour and dynamics of three-dimensional active dumbbell systems
• Characteristic features of self-avoiding active Brownian polymers under linear shear flow
• Coupling Turing stripes to active flows
• Density and inertia effects on two-dimensional active semiflexible filament suspensions
• Active Polymer Behavior in Two Dimensions: A Comparative Analysis of Tangential and Push-Pull Models
• Stress and Alignment Response to Curved Obstacles in Growing Bacterial Monolayers
• Anti-hyperuniform Critical States of Active Topological Defects
• Strain rate controls alignment in growing bacterial monolayers
• Aspect-ratio-dependent void formation in active rhomboidal and elliptical particle systems
• Sensitive particle shape dependence of growth-induced mesoscale nematic structure
• Riding the Wave: Polymers in Time-dependent Nonequilibrium Baths