Mathematical Models of Biofilm Deformation and Detachment

Bacterial biofilms are microbial depositions on immersed surfaces and are ubiquitous in natural and engineered environments. For example, they play a significant role in medical applications where they can grow on artificial implants and cause infections; they form dental plaques and contribute to tooth decay; they can be utilized to assist in clean-up of contaminated soils or groundwater aquifers; they accelerate corrosion of metal surfaces; and they are a main culprit behind contamination of drinking water systems and food processing equipment. Two essential aspects in many of the application areas just indicated are the way in which a biofilm deforms in response to shearing forces, and whether it ultimately detaches in response to the applied shear. In food processing plants for example, detached patches of biofilm material enter the production stream and can cause severe (sometimes even fatal) health risks for consumers. The research team will combine techniques from mathematical modelling and analysis, experimentation and computation in order to study the growth, deformation and detachment of biofilms immersed in fluid. A biofilm is a complex viscoelastoplastic material that changes its mechanical behaviour in response to environmental conditions, and suitable rheological constitutive relations will have to be developed in order to capture realistic biofilm behaviours. The research team will not only validate our model results in laboratory experiments, but also develop efficient and accurate numerical algorithms that are capable of simulating realistic 3D scenarios representing the fluid-biofilm interaction. The team expects that these computations will ultimately require the use of parallel computing resources and suitably parallelised versions of the underlying algorithms. Two computational approaches will be utilized: a parallelized implementation of the immersed boundary method (IBAMR) that has been released into the public domain; and a commercial finite element-based fluid-structure interaction code (ADINA-FSI). Initially the focus will be on the application of the model to the solution of problems in the food processing industry, engaging a number of industrial partners in that sector. Future work will concentrate on applying our modelling approach to the study of biofilms to other applications, including possibly the contamination of drinking water processing facilities, wastewater purification, groundwater bioremediation, and biofiltration to name just a few.