ARS | Publication request: Oxygen - Enemy or Friend for Microbial Fuel Cell Anode Performance?

Submitted to: Institute of Biological Engineering Meeting Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: March 6, 2010
Publication Date: N/A

Technical Abstract: Until recently, scientists and engineers have held a strong belief that oxygen intrusion into the anode chamber of a bioelectrochemical system (BES) is detrimental to microbial fuel cell (MFC) performance because oxygen acts as an alternate electron acceptor. This would, according to recent beliefs, reduce the electron flow to the anode electrode, and therefore electrical current generation. However, our recent research with two very different model anode-respiring bacteria – the direct-electron-transfer bacterium Shewanella oneidensis and the phenazine-producing bacterium Pseudomonas aeruginosa – has shown that the microbial current production can be significantly enhanced in the presence of oxygen. What are the reasons for this controversial observation? We found that S. oneidensis is able to use its substrate lactate more completely and efficiently, and therefore oxygen intrusion results in higher growth rates and higher overall activity of the culture. Although a higher percentage of electrons is dissipated to oxygen, the total current production increases. For P. aeruginosa, we found a double benefit of oxygen in the BES system. Again, the growth rate of the organism is higher, resulting in increased phenazine production, and thus current generation. But oxygen also increases the selection pressure of P. aeruginosa on the microbial community because phenazines bring about their antibiotic action by producing super oxide ions and hydrogen peroxide from oxygen. If these model anode-respiring microorganisms can be positively affected by oxygen, can we also apply this knowledge to design more robust and more efficient, oxygen tolerant mixed anodic microbial communities? Or, what other possible bioelectrochemical applications besides the generation of power in an MFC can be developed with this new knowledge. With this presentation, we want to shed light on these new discoveries and aim to initiate some "out of the box" thinking on traditional MFC functions.