Anisotropic nutrient transport in three-dimensional single species bacterial biofilms

• Published in: Biotechnology and bioengineering Vol. 109; no. 5; pp. 1280 - 1292
• Main Authors: Van Wey, A.S., Cookson, A.L., Soboleva, T.K., Roy, N.C., McNabb, W.C., Bridier, A., Briandet, R., Shorten, P.R.
• Format: Journal Article
• Language: English
• Published: Hoboken Wiley Subscription Services, Inc., A Wiley Company 01.05.2012; Wiley Subscription Services, Inc; Wiley
• Subjects: Agricultural sciences; Anisotropy; Bacteria; Bacteria - chemistry; Bacteria - growth & development; Bacterial Physiological Phenomena; Biofilms; Biofilms - growth & development; Diffusion; fermentation; Life Sciences; Mathematical models; Metabolism; Models, Statistical; monod kinetics; Monte Carlo simulation; Organic Chemicals - analysis; diffusion; CONFOCAL MICROSCOPY; EXTRACELLULAR POLYMERIC SUBSTANCES; HETEROGENEOUS BIOFILMS; INTESTINAL MICROFLORA; EFFECTIVE DIFFUSIVITIES; NUCLEAR-MAGNETIC-RESONANCE; DIFFUSION-COEFFICIENTS; MASS-TRANSPORT; FLUORESCENCE CORRELATION SPECTROSCOPY; PHYSICAL-CHARACTERISTICS; fermentation; model; metabolism; monod kinetics
• ISSN: 0006-3592; 1097-0290
• DOI: 10.1002/bit.24390

The ability for a biofilm to grow and function is critically dependent on the nutrient availability, and this in turn is dependent on the structure of the biofilm. This relationship is therefore an important factor influencing biofilm maturation. Nutrient transport in bacterial biofilms is complex; however, mathematical models that describe the transport of particles within biofilms have made three simplifying assumptions: the effective diffusion coefficient (EDC) is constant, the EDC is that of water, and/or the EDC is isotropic. Using a Monte Carlo simulation, we determined the EDC, both parallel to and perpendicular to the substratum, within 131 real, single species, three‐dimensional biofilms that were constructed from confocal laser scanning microscopy images. Our study showed that diffusion within bacterial biofilms was anisotropic and depth dependent. The heterogeneous distribution of bacteria varied between and within species, reducing the rate of diffusion of particles via steric hindrance. In biofilms with low porosity, the EDCs for nutrient transport perpendicular to the substratum were significantly lower than the EDCs for nutrient transport parallel to the substratum. Here, we propose a reaction–diffusion model to describe the nutrient concentration within a bacterial biofilm that accounts for the depth dependence of the EDC. Biotechnol. Bioeng. 2012; 109:1280–1292. © 2011 Wiley Periodicals, Inc. The ability for a biofilm to grow and function is critically dependent on the structure of the biofilm. The authors showed that diffusion within bacterial biofilms was anisotropic and depth dependent. In biofilms with low porosity, diffusion perpendicular to the substratum was significantly lower than that parallel to the substratum.