Previous Article | Next Article 
Applied and Environmental Microbiology, December 2008, p. 7348-7355, Vol. 74, No. 23
0099-2240/08/$08.00+0 doi:10.1128/AEM.01639-08
Copyright © 2008, American Society for Microbiology. All Rights Reserved.
Comparison of Electrode Reduction Activities of Geobacter sulfurreducens and an Enriched Consortium in an Air-Cathode Microbial Fuel Cell
,
Shun'ichi Ishii,1,4*
Kazuya Watanabe,2,5
Soichi Yabuki,1
Bruce E. Logan,3 and
Yuji Sekiguchi1
Institute for Biological Resource and Functions, National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1 Higashi, Tsukuba, Ibaraki 305-8566, Japan,1 Research Center for Advanced Science and Technology, University of Tokyo, 4-6-1 Komaba, Tokyo 153-8904, Japan,2 Department of Civil and Environmental Engineering, Penn State University, University Park, Pennsylvania 16802,3 JSPS, 1-6 Chiyoda-ku, Tokyo 102-8471, Japan,4 Hashimoto Light Energy Conversion Project, ERATO, JST, Hongo, Bunkyo-ku, Tokyo 113-8656, Japan5
Received 16 July 2008/ Accepted 29 September 2008
An electricity-generating bacterium, Geobacter sulfurreducens PCA, was inoculated into a single-chamber, air-cathode microbial fuel cell (MFC) in order to determine the maximum electron transfer rate from bacteria to the anode. To create anodic reaction-limiting conditions, where electron transfer from bacteria to the anode is the rate-limiting step, anodes with electrogenic biofilms were reduced in size and tests were conducted using anodes of six different sizes. The smallest anode (7 cm2, or 1.5 times larger than the cathode) achieved an anodic reaction-limiting condition as a result of a limited mass of bacteria on the electrode. Under these conditions, the limiting current density reached a maximum of 1,530 mA/m2, and power density reached a maximum of 461 mW/m2. Per-biomass efficiency of the electron transfer rate was constant at 32 fmol cell–1 day–1 (178 µmol g of protein–1 min–1), a rate comparable to that with solid iron as the electron acceptor but lower than rates achieved with fumarate or soluble iron. In comparison, an enriched electricity-generating consortium reached 374 µmol g of protein–1 min–1 under the same conditions, suggesting that the consortium had a much greater capacity for electrode reduction. These results demonstrate that per-biomass electrode reduction rates (calculated by current density and biomass density on the anode) can be used to help make better comparisons of electrogenic activity in MFCs.
* Corresponding author. Mailing address: National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1 Higashi, Tsukuba, Ibaraki 305-8566, Japan. Phone: 81-29-861-6026. Fax: 81-29-861-6400. E-mail: shunichi-ishii{at}aist.go.jp
Published ahead of print on 3 October 2008.
Supplemental material for this article may be found at http://aem.asm.org/.
Applied and Environmental Microbiology, December 2008, p. 7348-7355, Vol. 74, No. 23
0099-2240/08/$08.00+0 doi:10.1128/AEM.01639-08
Copyright © 2008, American Society for Microbiology. All Rights Reserved.
Copyright © 2009 by the American Society for Microbiology. For an alternate route to Journals.ASM.org, visit: http://intl-journals.asm.org | More Info»