Extracellular polymers control bacterial biofilm expansion and material properties

Biofilms, surface-attached communities of bacterial cells, are a concern in health and in industrial operations because of persistent infections, clogging of flows, and surface fouling. In this talk, I will explore the consequences to biofilm growth and robustness when the biofilm matrix functions as a material that is responsive to environmental perturbations such as changes in osmotic pressure. Using Vibrio cholerae as the model organism, we showed that matrix production enables biofilm-dwelling bacterial cells to establish an osmotic pressure differential between the biofilm and the external environment. The pressure difference promotes colony biofilm expansion on nutritious surfaces, controls growth of submerged biofilms, and enables matrix-producing cells in biofilms to exclude non-matrix-producing cheaters and to resist invasion by planktonic cells. Furthermore, we discovered how extracellular polysaccharides, proteins, and cells function together to define biofilm mechanical and interfacial properties.