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DY: Fachverband Dynamik und Statistische Physik
DY 5: Active Biological Matter I (joint session BP/CPP/DY)
DY 5.1: Invited Talk
Monday, March 22, 2021, 09:00–09:30, BPb
The tortoise and hare: how moving slower allows groups of bacteria to spread across surfaces — Oliver Meacock1,2, Amin Doostmohammadi3, Kevin Foster1, Julia Yeomans1, and •William Durham1,2 — 1University of Oxford, United Kingdom — 2University of Sheffield, United Kingdom — 3University of Copenhagen, Denmark
Bacteria use tiny grappling hook like appendages called pili to pull themselves across solid surfaces. While pili-based motility has been widely studied in solitary Pseudomonas aeruginosa cells, this species also uses pili to collectively migrate across surfaces when they are densely packed together in a colony. Interestingly, we find genotypes that individually move slower can collectively migrate faster as a group. Using theory developed to study liquid crystals, we demonstrate that this effect is mediated by the physics of topological defects, points where cells with different orientations meet one another. Our analyses reveal that when defects with a topological charge of +1/2 collide with one another, the fast-moving mutant cells rotate vertically and become trapped. By moving more slowly, wild-type cells avoid this trapping mechanism, allowing them to collectively migrate faster. Our work suggests that the physics of liquid crystals has played a pivotal role in the evolution of collective bacterial motility by exerting a strong selection for cells that exercise restraint in their movement.
Full paper in Nature Physics available free of charge at: https://rdcu.be/cbcgc