The influence of acidity on microbial fuel cells containing Shewanella oneidensis

Authors

• Justin C. Biffinger, US Naval Research LaboratoryFollow
• Jeremy Pietron, US Naval Research Laboratory
• Orianna Bretschger, University of Southern California
• Lloyd J. Nadeau, Air Force Research Laboratory
• Glenn R. Johnson, Air Force Research Laboratory
• Cynthia C. Williams, US Naval Research Laboratory
• Kenneth H. Nealson, University of Southern California
• Bradley R. Ringeisen, Naval Research LaboratoryFollow

Date of this Version

2008

Comments

Published in Biosensors and Bioelectronics 24 (2008) 900-905; doi:10.1016/j.bios.2008.07.034

Abstract

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, to electrodes has not been examined. Miniature MFCs using bare graphite felt electrodes and nanoporous polycarbonate membranes with MR-1 or DSP10 cultures generated >8W/m³ and ∼400μA 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. S. oneidensis MR-1 was determined to be more suitable than DSP10 for MFCs with elevated acidity levels. The concentration of riboflavin in the bacterial cultures was reduced significantly at pH 5 for DSP10, as determined by high performance liquid chromatography (HPLC) of the filter sterilized growth media. In addition, these results suggest that mediator biosynthesis and not solely bacterial concentration plays a significant role in current output from S. oneidensis containing MFCs.