Increasing Cell Potential of a Microbial Fuel Cell Using Enzyme Modification
Eric Moore and Andrew Piefer
Chemistry Hartwick College Oneonta NY United States.
Microbial fuel cells are a useful means of utilizing the energy extracted from substrates during the metabolism of microorganisms. During this process a fuel source is oxidized and high energy electrons are transferred from the fuel source to NAD+ to form the electron carrier NADH. In a microbial fuel cell NADH electrons are used to power an external circuit that is placed between an anode and cathode chamber. Because of the dependence of this process on current-inducing electrons from NADH, we believe that maximizing the microbial production of NADH will make the bacteria more electrochemically active. To do this, we can overexpress enzymes in the glycolysis pathway that allosterically regulate substrate flux such phosphofructokinase and to a lesser extent, pyruvate kinase. Alternatively, we can potentially inhibit enzymes that catalyze the oxidation of NADH during microbial fermentation, such as acetaldehyde dehydrogenase, D-lactate dehydrogenase, and fumarate reductase. All three of these enzymes catalyze the oxidation of NADH to form fermentation products that receive electrons that would otherwise be used to power the circuit. The differences in cell potential between control and modified E. coli will reflect any changes in the capabilities of these bacteria to transfer electrons in a fuel cell environment. This project was funded by NSF Award #0966085 awarded to Hartwick College and the Hartwick College Department of Chemistry.