Team:Korea U Seoul/Demonstrate
Demonstrate
Demonstrate
Our project is about creating an Enzymatic Microbial Fuel cell that uses agar as its energy source. We designed the battery device this way.
First, E.coli that displays agar degrading enzymes degrade agar to produce galactose and NADH. Galactose is then used by E.coli to produce lactate and formate which shewanella oneidensis can use to generate electricity. NADH is used by diaphorase to generate electricity as well.
This is how we made the prototype.
Shewanella oneidensisMR-1, BW25113 with displayed agar degrading enzymes, cell lysate of diaphorase expressed BL21(DE3), and cell lysate of TEV expressed BL21(DE3) was put into the anode chamber. (The function of TEV is explained in the Experiment section.) Agar was used as the substrate. The battery device without agar was set as the control.
As you can see in the graph above, the battery with agar generated more electricity than the control. The voltages the control generate is nearly 0, while our prototype EMFC generates 0.1V of electricity. Our prototype EMFC apparently works as expected.
However, the voltage generated is not very high. This was expected due to some reasons. First, our battery device was not designed to generated high electricity. To get high yield, you need electrodes with large surface area but the electrodes of our device has small surface area since it is only a thin carbon paper with coated back. We designed our device this way for precise comparison. Second, our added diaphorase was in free state which means the majority of the diaphorase was not doing much to generate electricity. A lot of EFC relate theses fixes diaphorase onto the electrode for higher yield, and stabilization of the enzymes.
Since we succeeded in operating the prototype EMFC we designed, our next goal is to improve electricity yield. This includes improving the battery device with better electrodes, optimizing the amount of reagents and cells in the device, and purifying diaphorase to get rid of useless materials.
