The report, published in the December 12th issue of Science, found that the bacterium a member of a family of organisms that can remove dissolved uranium from groundwater possesses extraordinary capabilities to transport electrons and "reduce" metal ions as part of its energy-generating metabolism. The authors conclude that Geobacter "clearly has potential for bioremediation of radioactive metals and electricity generation."

Reduction is a chemical process during which electrons are added to metal ions. As a result, the metals become less soluble (dissolvable) in water and precipitate into solids, which are more easily removed. Small charges of electricity are also created through the reduction process.

Geobacter's capacity for reduction is enhanced by more than 100 of its genes that appear to encode for various forms of c-type cytochromes. Those are proteins which facilitate electron transfers and metal reduction during the organism's energy metabolism. The presence of those c-type cytochrome genes the most and the greatest variety found so far in a bacterial species are thought to give G. sulfurreducens a significant capacity and flexibility to reduce metals or create electricity.

By analyzing the genome, scientists discovered that the microbe has genes that give it the capacity to move towards metallic compounds. In addition, G. sulfurreducens which scientists had previously regarded as an anaerobic organism (living in environments without oxygen) also has genes that could allow it to function in the presence of oxygen under certain conditions.

"We've provided a comprehensive picture that has led to fundamental
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Contact: Robert Koenig
rkoenig@tigr.org
301-838-5880
The Institute for Genomic Research
11-Dec-2003