Probing Pathogenic Biofilm Mechanics under Host-Like Conditions

Chronic infections are predominantly associated with biofilm-forming bacteria and immune cell clearance of the infection depends on the mechanical properties of the biofilm extracellular polymeric substance (EPS) matrix. Despite the importance of biofilm mechanical properties in mediating host-pathogen interactions, mechanical characterization of pathogenic biofilms remains challenging due to the inherent fragility of biofilms. Here, using a custom-built mechanical tester, The Uniaxial Tensile Tester for UltraThin films (TUTTUT), we directly measure how the complete uniaxial stress-strain relationship of surface-grown Vibrio cholerae biofilms changes in response to host factors. From our measurements, we determine host factors which can alter the mechanical behavior of biofilms.  Overall, this work provides a framework for studying pathogenic biofilm mechanics and fundamental knowledge on the impact of the surrounding host environment on biofilm mechanical properties.