1. Background on Microbial Fuel Cells A bio-electric system –Microbially maintained ion gradient fuels electron flow, generating electricity Two phases of microbial fuel cells –Degradation of organic matter (cellulose) –Electricity generation (transfers ions)

3. Examples of Microbial Fuel Cells

5. Background on MFCs Mixed Cultured MFCs –Advantages: Full, robust utilization of breakdown products Wide range of functionality Single Strain MFCs –Advantages: Simplification of bio-component MFC Better capacity for genetic engineering in MFCs

6. Simultaneous Cellulose Degradation and Electricity Production by Enterobacter cloacae in a Microbial Fuel Cell Authors: Farzaneh Rezaei, Defeng Xing, Rachel Wagner, John M. Regan, Tom L. Richard, and Bruce E. Logan Penn State University

7. Methods Isolation by DTE (dilution to extinction) –Based on exoelectrogenartion and cellulose degradation PCR (polymerase chain reaction), DGGE (denaturing gradient gel electrophoresis), and 16S rRNA sequence comparison Biochemical comparison –Measured growth with various carbon sources

9. Results DGGE of dilution to extinction

10. Results Enterobacter cloacae –Gram-negative –Facultative anaerobe –Rod-shaped –Motile by peritrichous flagella

11. Discussion Enterobacter cloacae MFC is first single strained MFC. This MFC is limited by complete metabolism and toxin accumulation. Measuring exoelectrogeneration potential by Fe(III) reduction is flawed Synergistic effects of mixed culture MFCs are poorly understood

12. Comparison of electricity production

13. Critique Single wastewater source –One source limits the potential microbes. –Researchers should have isolated microbes from several sources. Isolation and characterization was narrow –Other microbes from mixed cultures should have been examined closely to understand the mechanisms behind mixed culture synergy.

14. References Christy, A. D., 2008. Cellulose Conversion to Electricity in Microbial Fuel Cells: Challenges and Constraints. Microbial Fuel Cells First International Symposium Rezaei, Farzaneh, et al. 2009. Simultaneous cellulose degradation and electricity production by Enterobacter cloacae in a Microbial Fuel Cell. Appl. Environ. Microbiol. 75:3673–3678 Zuo, Y., et. al. 2008. Isolation of the exoelectrogenic bacterium Ochrobactrum anthropi YZ-1 by using a U-tube microbial fuel cell. Appl. Environ. Microbiol. 74:3130-3137

15. Questions?