The influence of acidity on microbial fuel cells containing Shewanella oneidensis.
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/m(3) and approximately 400muA 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.
Biffinger
Justin C
JC
Chemistry Division, US Naval Research Laboratory, 4555 Overlook Avenue, SW, Washington, DC 20375, USA.
Pietron
Jeremy
J
Bretschger
Orianna
O
Nadeau
Lloyd J
LJ
Johnson
Glenn R
GR
Williams
Cynthia C
CC
Nealson
Kenneth H
KH
Ringeisen
Bradley R
BR
D001674:Bioelectric Energy Sources; D019149:Bioreactors / Q000382:microbiology*; D004579:Electron Transport; D004867:Equipment Design; D019544:Equipment Failure Analysis; D006863:Hydrogen-Ion Concentration; D020592:Shewanella / Q000737:chemistry* / Q000502:physiology*