Washington State University CAREER:Electrochemically Active Biofilms 0954186
Electrochemically active biofilms (ECABs) where microorganisms are grown through the direct electrochemical stimulation via electrodes, as opposed to being exposed to chemicals that serve as electron donors and acceptors, are widely used in bioremediation, wastewater treatment, biofuel and biochemical production, microbial fuel cells, corrosion studies, and in sensor development. The electron transfer processes between biofilm cells and the solid electrodes, however, are poorly understood. This research quantifies redox-mediated electron transfer rates with the goal of determining fundamental scientific understandings of how to stimulate or, depending on the application, limit electrochemically-induced cell growth rates and/or product formation. The work will also create a quantitative, mechanism-based, mathematical model that can be used to predict rates of biofilm cell growth and product formation using electrochemical, diffusion-reaction, and genome-scale constraint-based models to predict electron transfer rates and their impact on microbial metabolic processes. Research will involve experiments with three model organisms: Geobactor sulfurreducens, Zymonmonas mobilis, and Acinetoobater baumanii. Experiments will be carried out in flat-plate reactors and constant-depth film fermentors. Critical aqueous phase characteristics and electron transfer rates will be measured using innovative voltammetric techniques, microsensors that can measure local chemistry, and the electrochemical activities of the biofilms. Biofilm structure will be examined via confocal scanning laser microscopy. Broader impacts of the work are far-reaching and include potential societal and economic implications related to microbial fuel cells, biofuels, bioremediation, and biomedical applications. The project will produce the first mathematical model for predicting electron transfer rates and their correlation to microbial metabolic reactions, which can be used to predict metabolic reactions and cell growth and biofilm production rates. In addition, the project demonstrates the strong integration of education and research that includes creation of a novel, hands-on, microbial fuel cell education module for college undergraduates and another for high school students. High school teachers and students from schools in Idaho and Washington State with high Hispanic and Native American enrollments will be engaged in the project to try and broaden participation of minority students in STEM fields.
