Influence of Acidity on Microbial Fuel Cells Containing Shewanella Oneidensis (PREPRINT); Journal article

摘要

Microbial fuel cells (MFCs) traditionally operate at pH values between 6 and 8. However, the effect of pH on the growth and electron transfer abilities of Shewanella oneidensis MR-1 (wild-type) and DSP10 (spontaneous mutant), bacteria commonly used in MFCs, has not been characterized. Miniature MFCs using bare graphite felt electrodes and nanoporous polycarbonate membranes with MR-1 or DSP10 cultures generated > 8 W/cu m and approximately 400 microA between pH 6- 7. The DSP10 strain significantly outperformed MR-1 at neutral pH but underperformed at pH 5. Higher concentrations of DSP10 were sustained at pH 7 relative to that of MR-1, whereas at pH 5 this trend was reversed indicating that cell count was not solely responsible for the observed differences in current. The presence of autologous mediators in the cultures was reduced significantly at pH 5 for DSP10, as determined by physical and electrochemical measurements of the filter sterilized growth media. Overall, MR-1 was found to be more suitable for MFCs when low pH-operation was desired. These results suggest that proton concentration plays an integral role in the biosynthesis of mediators and that the current produced by S. oneidensis MFCs is aided by the presence of these electron shuttles in the anolyte.