Dresden 2026 – wissenschaftliches Programm

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BP: Fachverband Biologische Physik

BP 11: Franco-German Session: Bacterial Biophysics I

BP 11.5: Vortrag

Dienstag, 10. März 2026, 10:30–10:45, BAR/0106

Differential pili interactions trigger colony eversion and dissemination of bacteria — Stephan Wimmi¹, •Isabelle Wielert¹, Kai Zhou², Marc Hennes¹, Benedikt Sabass², and Berenike Maier¹ — ¹Institute for Biological Physics, and Center for Molecular Medicine Cologne, University of Cologne, Germany — ²Institute for Infectious Diseases and Zoonoses, Ludwig-Maximilians-Universitaet Munich, Germany

Attractive forces between cells determine the shape and sorting behaviour of bacterial colonies. During colony development, chemical gradients form within the colony but it is unclear how they affect cohesion. Here, we discover global eversion of colonies formed by Neisseria gonorrhoeae. Like a jet, the inner core flows towards the periphery where it is partially dispersed and partially spreads around the core of the colony. Living dispersed cells leading to fast dissemination. The eversion depends on local oxygen depletion that reduces cellular attraction: prior to eversion the colony consists of a weakly cohesive spherical core surrounded by a strongly cohesive shell. A computational model reveals when the thickness of the strongly interacting shell falls below a critical value a non-linear instability initiates colony-wide eversion. Simulations predict that an increase of cohesion forces among the bacteria suppresses colony eversion. This was confirmed experimentally by a genetic modification that increases attractive forces among bacteria. Overall, we conclude that a gradient of oxygen pushes the colony out of its equilibrium state and that non-linear instabilities trigger cellular fluxes during relaxation to a new stationary state.

Keywords: Biophysics; Biofilms; Image analysis; Bacterial mechanics; Confocal images