Mechanical principles of biofilm formation revealed by single-cell resolution imaging

Biofilms are surface-associated bacterial communities embedded in an extracellular matrix. Biofilm cells are more resistant to antibiotics than their planktonic counterparts, which is a major problem in the context of chronic infections. We still lack a fundamental biophysical understanding of how bacteria, in time and space, build these three-dimensional structures that attach to surfaces and resist mechanical and chemical perturbations. During this talk, I will present a technique to image living, growing bacterial biofilms from single founder cells to ten thousand cells at single-cell resolution. Using the human pathogen Vibrio cholerae as a model biofilm former, we discovered that the biofilm develops from a disordered, two-dimensional layer of founder cells into a three-dimensional structure with a vertically aligned core. Using computer simulations, we found that verticalization proceeds through a series of localized mechanical instabilities on the cellular scale. By modulating cell lengths and osmotic conditions, we quantitatively tested the predictions made from the agent-based simulations.