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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?