A tiny bacterium recovered from sediment may power batteries of the future. In a report published today in Nature Biotechnology, researchers describe a primitive microbial fuel cell that can convert simple sugars into electricity with 81 percent efficiency. Unlike previous attempts to manufacture such batteries, the novel design does not require unstable intermediaries to shuttle electrons and thus holds promise for producing energy from sugar-containing waste materials.

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."