Mechanical resilience of biofilms towards environmental perturbations mediated by extracellular matrix

Biofilms are surface-associated communities of bacterial cells embedded in an extracellular matrix (ECM). Biofilm cells can survive and thrive in various dynamic environments causing tenacious problems in healthcare and industry. Biofilms can be considered as soft, viscoelastic materials and exhibit remarkable mechanical resilience. How biofilms achieve such resilience towards various environmental perturbations remain unclear, although ECM has been generally considered to play a key role. Here, we use Vibrio cholerae (Vc) as a model organism to investigate biofilm mechanics in the nonlinear rheological regime by systematically examining the role of each constituent matrix component. Combining rheological measurements and molecular dynamics simulations, we quantitatively characterize the mechanical behaviors of various mutant biofilms and investigate their distinct mechanical phenotypes including mechanics-guided morphologies, nonlinear viscoelastic behavior, and recovery from large shear forces and heating. Our findings provide physical insights into the structure-property relationship of biofilms, which could be potentially employed to design biofilm removal strategies or, more forward-looking, engineer biofilms as beneficial, functional soft materials in dynamic environments.