A three-phase model for biofilm formation on a porous solid surface

We investigate the growth kinetics of bacterial biofilms on porous substrates. A three-phase model is developed, which accounts explicitly for the cell phase, extracellular matrix (ECM), and nutrient-rich aqueous phase. We use the thin-film approximation as the characteristic height of the biofilm is much smaller than its characteristic radius. We use the 2D axisymmetric model to capture biofilm growth on a porous agar substrate. Our model accounts for osmotic flux and predicts the spatiotemporal variations of the volume fractions of the different phases and the nutrient concentrations in the biofilm and the substrate. An increase in surface tension helps redistribute biomass radially. Our model captures the behavior of different kinds of biofilms: films characterized by low (yeast) and high (bacterial) ECM content. The predictions of our model are quantitatively validated with the experimental data from the literature. Our model provides insights on the role of different parameters on biofilm growth, which can be used to develop strategies to prevent or accelerate biofilm formation on surfaces.