The propagation of active-passive interfaces in bacterial swarms

Abstract

Propagating interfaces are ubiquitous in nature, underlying instabilities and pattern formation in biology and material science. Physical principles governing interface growth are well understood in passive settings; however, our understanding of interfaces in active systems is still in its infancy. Here, we study the evolution of an active-passive interface using a model active matter system, bacterial swarms. We use ultra-violet light exposure to create compact domains of passive bacteria within Serratia marcescens swarms, thereby creating interfaces separating motile and immotile cells. Post-exposure, the boundary re-shapes and erodes due to self-emergent collective flows. We demonstrate that the active-passive boundary acts as a diffuse interface with mechanical properties set by the flow. Intriguingly, interfacial velocity couples to local swarm speed and interface curvature, suggesting that an active analogue to classic Gibbs-Thomson-Stefan conditions controls boundary propagation. Our results generalize interface theories to mixing and segregation in active systems with collective flows.

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Cited by in corpus (26)

• Active Turbulence
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• Dynamics of active liquid interfaces
• Trade-offs in phenotypic noise synchronize emergent topology to actively enhance transport in microbial environments
• Morphological transitions of active Brownian particle aggregates on porous walls
• Fingering Instability of Active Nematic Droplets
• Microbial Active Matter: A Topological Framework
• Propagation of active nematic-isotropic interfaces on substrates
• Active nematic-isotropic interfaces in channels
• Dispersion of activity at an active-passive nematic interface
• Scaling regimes of active turbulence with external dissipation
• Director alignment at the nematic-isotropic interface: elastic anisotropy and active anchoring
• Inter-particle adhesion regulates the surface roughness of growing dense three-dimensional active particle aggregates
• Self-assembly of active core corona particles into highly ordered and self-healing structures
• Stability of the interface of an isotropic active fluid
• Equilibrium morphology of tactoids in elastically anisotropic nematics
• Nonlinear spontaneous flow instability in active nematics
• Interface dynamics of wet active systems
• Active-passive mixtures with bulk loading: a minimal active engine in one dimension
• Deep Learning-based Detection of Bacterial Swarm Motion Using a Single Image
• Dynamics and rupture of doped Motility Induced Phase Peparation
• Conservation laws and slow dynamics determine the universality class of interfaces in active matter
• A Data-Driven Statistical Description for the Hydrodynamics of Active Matter
• Density Fluctuations and Energy Spectra of 3D Bacterial Suspensions
• Irreversibility in scalar active turbulence: The role of topological defects
• Dynamical arrest in active nematic turbulence