Biological function of topological defects in swarming Bacillus subtilis

Determine the biological function of topological defects (±1/2 disclinations) in the nematic organization of Bacillus subtilis swarming colonies, specifying the roles these defects play in colony physiology and dynamics.

Background

The paper demonstrates that Bacillus subtilis swarms exhibit active nematic features, including ±1/2 defects whose locations and orientations are strongly coupled across layers, and flow patterns that differ from other active systems (e.g., a distinct influx toward −1/2 defect cores).

Although the authors hypothesize that defects and their self-propulsion may help maintain nematic turbulence leading to well-mixed colonies, they explicitly state that the biological function of these defects in swarming bacteria is still unclear.