A notably innovative approach toward increasing the microbial production of an end product is electrostimulation. Electrical stimulation of microbial metabolite production is based on the use of an artificial electron carrier such as neutral red, allowing an electric current to indirectly supply the electron-driving force needed to generate a proton-motive force for energy conservation and the electrons needed for growth and end product production (24).
The system involves the use of an electrochemical bioreactor utilizing an anodic chamber and a cathodic chamber divided by a cation selective membrane (24). The cathodic chamber is used as the fermentation vessel. The neutral red serves as a reduced electron carrier and migrates from the anode to the cathode where it enters the cells and couples to a suitable redox enzyme system which accepts the electrons. Electrostimulation has been used to increase l-glutamic acid production by Brevibacterium flavum (25), and shows promise with other fermentation processes (26).
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