Large-scale orientational order in bacterial colonies during inward growth

Abstract

During colony growth, complex interactions regulate the bacterial orientation, leading to the formation of large-scale ordered structures, including topological defects and microdomains. These structures may benefit bacterial strains, providing invasive advantages during colonization. Active matter dynamics of growing colonies drives the emergence of these ordered structures. However, additional biomechanical factors also play a significant role during this process. Here we show that the velocity profile of growing colonies creates strong radial orientation during inward growth when crowded populations invade a closed area. During this process, growth geometry sets virtual confinement and dictates the velocity profile. Herein, flow-induced alignment and torque balance on the rod-shaped bacteria significantly differed, resulting in new stable orientational equilibrium in the radial direction. Our analysis revealed that the dynamics of these orientational defects depend on bacterial length and can promote the survival of the longest bacteria around localized nutritional hot spots. The present results indicate a new mechanism underlying structural order and provide mechanistic insights into the dynamics of bacterial growth on complex surfaces.

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Cited by in corpus (9)

• Topological active matter
• Molecular-scale substrate anisotropy and crowding drive long-range nematic order of cell monolayers
• Collective mechano-response dynamically tunes cell-size distributions in growing bacterial colonies
• Phase behaviour and dynamics of three-dimensional active dumbbell systems
• Stress and Alignment Response to Curved Obstacles in Growing Bacterial Monolayers
• Strain rate controls alignment in growing bacterial monolayers
• Motility and self propulsion of active droplets
• Sensitive particle shape dependence of growth-induced mesoscale nematic structure
• Biofilm self-patterning: mechanical forces drive a reorientation cascade