Computational modelling to predict how extracellular polymeric substances production on biofilm mechanics and detachment

A wide range of microorganisms produce extracellular polymeric substances (EPS) that are fundamental for microbial life. EPS provides many functions, such as adhesion to surfaces and cohesion to maintain the mechanical stability of the biofilm system. However, it remains elusive how the extracellular polymeric substances production on biofilm mechanics and detachment. It is difficult to quantify EPS by microscopy or chemistry analysis due to the complexity of the chemistry, as well as extraction and purification techniques. Although EPS is complex, the computational modelling could be simplified to represent its physical function rather than the polymer components, hence, to gain better understanding of the contribution of EPS production to biofilm mechanical properties.

In this study, a three-dimensional individual-based model (IbM) of biofilm was developed by coupling the computational fluid dynamics approach (CFD) with the discrete element method (DEM). We have modelled a bacterial mutant that can produce the same type of EPS at different levels. Different EPS amount can be obtained by varying the relevant kinetic parameters in the model. We predicted the effect of EPS amount on the mechanical properties of biofilms and biofilm detachment.