Oxygen exposure promotes fuel diversity for Shewanella oneidensis microbial fuel cells

Miniature microbial fuel cells (mini-MFCs) were used to monitor the current generated by Shewanella oneidensis DSP10 under both anaerobic and aerobic conditions when exposed to glucose as a potential electron donor. In addition to glucose, other carbon fuels including fructose, sucrose, acetate, and ascorbic acid were also tested. When the anolyte containing S. oneidensis was grown in the presence of oxygen, power densities of 270 ± 10, 350 ± 20, and 120 ± 10 W/m 3 were recorded from the mini-MFC for glucose, fructose, and ascorbic acid electron donors, respectively, while sucrose and acetate produced no response. The power produced from glucose decreased considerably (≤100 W/m 3) if strictly anaerobic conditions were maintained. Based on the previously published proteomic and genomic literature on S. oneidensis, this reduction in power output is most likely due to the differential expression of proteins by these bacteria when grown under oxygen-rich or anoxic conditions. The power densities generated from the mini-MFC exposed to oxygen led to significant changes in current production over time with repeated feedings of these carbon nutrients. This work expands the breadth of potential electron donors for S. oneidensis MFCs and demonstrates the importance of studying microbial anolytes under diverse environmental conditions.