A Microfluidic Gradient Mixer-Flow Chamber as a New Tool to Study Biofilm Development under Defined Solute Gradients.

Understanding the dynamics of biofilm development in response to chemical cues and signals is required toward the development of controllable biofilm-mediated bioprocesses. In this study, we report a new biofilm growth system that integrates a microfluidic gradient mixer with a biofilm growth chamber. The biofilm growth system allows biofilms grow under defined solute gradients and enables non-destructively monitor the biofilm development dynamics in response to the defined gradients. The solute gradients generated in the system were simulated and then validated experimentally. We then demonstrated the applicability of the biofilm growth system in studying biofilm development under defined solute gradients. Specifically, we examined biofilm development of Shewanella oneidensis and Comamonas testosteroni under a defined calcium and nitrate gradient, respectively. Using two C. testosteroni strains (WDL7 and I2), we further demonstrated the applicability of our biofilm growth system to study the development of co-culture biofilms under a defined solute gradient. Our results showed that the biofilm growth system we developed here can be a promising tool to reveal the dynamics of biofilm development in response to chemical cues and signals as well as the inter-organism interactions in co-culture biofilms. This article is protected by copyright. All rights reserved.