Abstract
The goal of this study is to enhance the efficiency of bacterial extracellular electron transfer (EET) in Shewanella oneidensis MR-1 by enhancing adhesion to the electrode surface. Our results clearly show a major difference in attachment and behavior of S. oneidensis MR-1 for Ca2+, Pb2+, Cd2+, and Mg2+ compared to the control. The final microbial coverage, as measured by confocal microscopy and cathodic peak charge in cyclic voltammetry (Qpc), increases with increasing metal ion concentrations. We found the cells attached to the electrode increased more with the addition of metal ion concentrations in the following order of metals: Ca2+ > Pb2+ > Cd2+ > Mg2+ compared to the control. The effect of metal ions on metabolism of the bacteria was tested by the riboflavin production and glucose consumption. Metabolic activity mirrored the same order of the activity as the electrochemical results.
Highlights
An interesting field of science and technology is microbial fuel cells (MFC)
The goal of this study is to study whether metal ions enhance the efficiency of bacterial extracellular electron transfer (EET) in S. oneidensis MR-1 by enhancing adhesion to the electrode for improving the current output of microbial fuel cells
Bacteria samples were injected into the electrochemical cell for a two-hour anodic loading period at the potential of +0.2 V vs. Ag/AgCl
Summary
An interesting field of science and technology is microbial fuel cells (MFC). MFC use bacteria as the catalysts to convert the chemical energy of fuel (such as organic compounds) to electrical energy [1] [2]. This affects the various uses of MFC (electricity generation, wastewater treatment, biosensor, and hydrogen production) [3]. Different mechanisms for electron transfer from the microbe to the electrode surface have been proposed. Direct electron transfer can be via either direct contact between outer membrane cytochromes (MtrC and OmcA) with electrodes or through extracellular conductive connections called bacterial nanowires [7] [8]. Mediated electron transfer via soluble redox mediators (such as flavin and riboflavin) carries charge to the electrode [9] [10]
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