Swades K. Chaudhuri and Derek R. Lovley of the University of Massachusetts used Rhodoferax ferrireducens, a bacterium first isolated from sediments collected from an aquifer in Virginia, for their bacterial battery. When the researchers exposed R. ferrireducens to a solution of glucose in a chamber containing a graphite electrode they found that when the bacterium fed on the sugar, it transferred electrons directly to the electrode, producing a current. In addition, the sugar-fed R. ferrireducens continued to grow, resulting in stable, long-term power production. The scientists also tested the bacterium's ability to convert other sugars, including fructose, sucrose and xylose (present in wood and straw), and found it to be equally efficient.
The new findings should help scientists harness the abundant energy currently stored in waste from agricultural, municipal and industrial sources. The prototype fuel cells have such desirable features as the ability to recharge and minimum loss of energy while idling. Perhaps one day electronics will be sold with the caveat "bacteria not included."