Diffusion limited biofilm growth

Abstract

A two-dimensional Monte Carlo-diffusion model is described to model the growth of biofilms of Escherichia coli on different substrates. The model takes into account the diffusion rate of the nutrient solution that covers the biofilm and allows for the bacteria to grow with differing aspect ratios. Parameters are introduced to describe the relative growth and deposition rates and the amount of curvature of the bacteria over the surface. Limiting cases arise when the diffusion is slow, so that growth near existing bacteria is reduced, and when diffusion is fast, so that the available nutrient is uniformly distributed over the surface. The results are compared with experimental light microscopy and scanning force microscopy images of E. coli grown on a variety of different substrates. The parameters in the model are adjusted to show the different growth patterns that can form at different times and coverages.