RT Journal Article
SR Electronic
T1 A Thin-Film Lubrication Model for Biofilm Expansion Under Strong Adhesion
JF bioRxiv
FD Cold Spring Harbor Laboratory
SP 2021.11.16.468738
DO 10.1101/2021.11.16.468738
A1 Alexander K. Y. Tam
A1 Brendan Harding
A1 J. Edward F. Green
A1 Sanjeeva Balasuriya
A1 Benjamin J. Binder
YR 2021
UL http://biorxiv.org/content/early/2021/11/19/2021.11.16.468738.abstract
AB Understanding microbial biofilm growth is important to public health, because biofilms are a leading cause of persistent clinical infections. In this paper, we develop a thin-film model for microbial biofilm growth on a solid substratum to which it adheres strongly. We model biofilms as two-phase viscous fluid mixtures of living cells and extracellular fluid. The model tracks the movement, depletion, and uptake of nutrients explicitly, and incorporates cell proliferation via a nutrient-dependent source term. Notably, our thin-film reduction is two-dimensional and includes the vertical dependence of cell volume fraction. Numerical solutions show that this vertical dependence is weak for biologically-feasible parameters, reinforcing results from previous models in which this dependence was neglected. We exploit this weak dependence by writing and solving a simplified one-dimensional model that is computationally more efficient than the full model. We use both the one and two-dimensional models to predict how model parameters affect expansion speed and biofilm thickness. This analysis reveals that expansion speed depends on cell proliferation, nutrient availability, cell–cell adhesion on the upper surface, and slip on the biofilm–substratum interface. Our numerical solutions provide a means to qualitatively distinguish between the extensional flow and lubrication regimes, and quantitative predictions that can be tested in future experiments.Competing Interest StatementThe authors have declared no competing interest.