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)

Examples of Microbial Fuel Cells

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

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

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

Results

• DGGE of dilution to extinction

Results

• Enterobacter cloacae– Gram-negative– Facultative anaerobe– Rod-shaped– Motile by peritrichous flagella

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

Comparison of electricity production

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.

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

Questions?