Mechanical Principles of Biofilm Formation*

Biofilms are surface-associated bacterial communities embedded in an extracellular matrix. Biofilms are a major problem in the context of chronic infections, because biofilm dwelling cells have increased antibiotic resistance compared to their planktonic counterparts. In this talk, I will discuss about our recently progress in using Vibrio cholerae as a model biofilm former to reveal the mechanical principles behind biofilm formation. I will first present a new methodology to image living, growing bacterial biofilms at single-cell resolution, and demonstrate how cell-cell adhesion and cell-surface adhesion balance each other to cause V. cholerae to form an ordered three-dimensional biofilm. Next, I will demonstrate how matrix production enables biofilm cells to establish an osmotic pressure differential between the biofilm and the external environment, and use this osmotic pressure to facilitate biofilm expansion. Finally, I will present various mechanical instabilities that take place when biofilms grow on soft substrates.