Microbial response to environmental gradients in a ceramic-based diffusion system

• Published in: Biotechnology and bioengineering Vol. 100; no. 1; pp. 141 - 149
• Main Authors: Wolfaardt, G.M, Hendry, M.J, Birkham, T, Bressel, A, Gardner, M.N, Sousa, A.J, Korber, D.R, Pilaski, M
• Format: Journal Article
• Language: English
• Published: Hoboken Wiley Subscription Services, Inc., A Wiley Company 01.05.2008; Wiley; Wiley Subscription Services, Inc
• Subjects: Antimicrobial agents; antimicrobial testing; biofilm; Biofilms; Biofilms - growth & development; Biological and medical sciences; Bioreactors - microbiology; Biotechnology; Cell Culture Techniques - instrumentation; Cell Culture Techniques - methods; Cell Proliferation; Ceramics; Computer Simulation; enrichment of degradative communities; Environmental gradient; environmental gradients; Flow Injection Analysis - instrumentation; Flow Injection Analysis - methods; Fundamental and applied biological sciences. Psychology; Microbial activity; Microbiology; Microfluidic Analytical Techniques - instrumentation; Microfluidic Analytical Techniques - methods; Microscopy; Models, Biological; Nutrient concentrations; Porous media; Solid modeling; Solutes; Ultrafiltration - instrumentation; Ultrafiltration - methods; Gradient; enrichment of degradative communities; Biofilm; antimicrobial testing; Microorganism; Ceramic materials; Antimicrobial agent; environmental gradients
• ISSN: 0006-3592; 1097-0290; 1097-0290
• DOI: 10.1002/bit.21736

A solid, porous matrix was used to establish steady-state concentration profiles upon which microbial responses to concentration gradients of nutrients or antimicrobial agents could be quantified. This technique relies on the development of spatially defined concentration gradients across a ceramic plate resulting from the diffusion of solutes through the porous ceramic matrix. A two-dimensional, finite-element numerical transport model was used to predict the establishment of concentration profiles, after which concentration profiles of conservative tracers were quantified fluorometrically and chemically at the solid-liquid interface to verify the simulated profiles. Microbial growth responses to nutrient, hypochloride, and antimicrobial concentration gradients were then quantified using epifluorescent or scanning confocal laser microscopy. The observed microbial response verified the establishment and maintenance of stable concentration gradients along the solid-liquid interface. These results indicate the ceramic diffusion system has potential for the isolation of heterogeneous microbial communities as well as for testing the efficacy of antimicrobial agents. In addition, the durability of the solid matrix allowed long-term investigations, making this approach preferable to conventional gel-stabilized systems that are impeded by erosion as well as expansion or shrinkage of the gel. Biotechnol. Bioeng. 2008;100: 141-149.