Geobacter sulfurreducens, among other bacteria, are used in microbial fuel cells. Recent progress in fuel cell development using bacterial biofilms has been limited by a lack of understanding regarding the mechanisms that affect current production. One proposed mechanism is electron-hopping, which involves the transport of electrons through the biofilm by a sequence of redox reactions.
Sebastian Bonanni and co-workers, Lab de Bioelectroquimica, Mar del Plata, Argentina, have developed a kinetic mathematical model to understand the respiration process within bacteria. This model can reproduce experimental data and has identified the limiting step for current production within a Geobacter biofilm under a range of experimental conditions. This model can predict the fundamental electrochemical activity that produces current in Geobacter biofilms.
Metabolic activity, redox gradients, and finite thicknesses in the biofilm are shown to be accounted for by electron-hopping. Bonanni and team also suggest that the conductive nature of the biofilm is not representative of the actual electron transport pathway. This insight is expected to aid future development of this class of fuel cells.
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