Effects of Overexpressing a CType Cytochome Gene on Current Production of Geobacter Sulferreducens i

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Effects of Overexpressing a C-Type Cytochome
Gene on Current Production of Geobacter
Sulferreducens in a Microbial Bio-fuel Cell

• Student 1, Student 2, Student 3

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What is a Microbial Bio-Fuel Cell?

• Powered by bacteria that give off electrons
• Bacteria consume organic matter, and converts
  that matter into electrical energy
• The electrons are channeled to an electrode made
  of graphite

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Our Goal

• Optimize current production of the bacteria
  called Geobacter Sulfurreducens
• This will be done by means of genetically
  engineering the bacteria
• Independent Variable Over-expression of the
  C-Type Cytochrome gene GSU1176.
• Dependent Variable Current Production.

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Snapshot of Our Progress

• We have successfully grown fifteen cultures of
  Geobacter
• We have built one fuel cell that is currently
  operating (producing voltage and current)
• The genetic phase will be complete by the end of
  next quarter

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Overview

• How to culture Geobacter
• How to build a microbial bio-fuel cell
• Our results
• What still needs to be done

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Culturing Bacteria

• Ordered Geobacter from ATCC (American Type
  Culture Collection)
• Followed the included guidelines from ATCC for
  creating the bacterial media
• After five weeks, we grew sufficient cell mass to
  build the fuel cell

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Building the Fuel Cell

• The anode chamber is the positive pole
• The cathode chamber is the negative pole
• The bacteria dwell within the anode chamber, and
  the cathode chamber remains sterile

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Production of Electricity
This graph shows the changes in voltage about
three days after inoculation. The voltage is
expected to drop as soon as the bacteria consumes
all the organic material (aka food).
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Conclusions

• Geobacter can adjust to changes in solution
  density between itself and its environment.
• Voltage production does not follow an exponential
  curve. Instead, it follows a logistic curve.

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Connections

• Microbial bio-fuel cells are currently used for
  powering deep-sea sensors
• Geobacter is also used for cleaning toxic
  materials from ground water
• Our project is focused on enhancing the bacteria
  to be more efficient in electrical production
• Geobacter may one day power many common
  electronic devices such as calculators

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Next Steps

• This is just a snapshot.
• We will perform the genetic manipulations and
  examine their results on current production on a
  similar fuel cell.

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Acknowledgements

• Oregon State University Department of
  Microbiology
• Dr. Luis Sayavedra-Soto
• Dr. Walt Ream
• Dr. Dan Arp