(323e) Microstructure and Mechanical Properties of Bacterial Biofilms

Biofilms, a mass of biological material containing a large fraction of living microorganisms attached to a surface, are found on nearly every surface where nutrients are available. Although persistence of biofilms is necessary for many life processes, they can also cause significant technological or medical complications. A fundamental understanding of live microbial biofilm microstructure and mechanical properties and their interactions with the underlying substrate can lead to the development of new remedial strategies and/or materials. Here we report mechanical properties of dental pathogenic Streptococcus mutans biofilms, investigated using shear rheology. Biofilms were grown in physiologically relevant conditions − by developing a custom bioreactor that acts as a stand-alone, environmentally controlled culturing system − directly on the polystyrene coated bottom plate of the rheometer. Variation in the amount of extracellular polymeric compounds in the biofilms resulted in change of elastic modulus. Biofilm microstructure was studied by using confocal microscopy and it was found that the change of elastic modulus was caused by the change in extracellular polymeric substance (EPS) chemistry, biofilm microstructure, and water content. This simple but robust experimental technique presented here provided a valuable insight into the pathogenic properties of S. mutans biofilms and this technique us can easily be extended to other biofilm-material systems.