Geobacter Project

Geobacter species are of interest because of their novel electron transfer capabilities, impact on the natural environment and their application to the bioremediation of contaminated environments and harvesting electricity from waste organic matter. The first Geobacter species (initially designated strain GS-15) was isolated from the Potomac River, just down stream from Washington D.C. in 1987. This organism, known as Geobacter metallireducens,

G. metallireducens [larger image]
© 2005 eye of science

was the first organism found to oxidize organic compounds to carbon dioxide with iron oxides as the electron acceptor. In other words, Geobacter metallireducens gains its energy by using iron oxides (a rust-like mineral) in the same way that humans use oxygen. As outlined in the publication links, Geobacter metallireducens and other Geobacter species that have subsequently been isolated provide a model for important iron transformations on modern earth and may explain geological phenomena, such as the massive accumulation of magnetite in ancient iron formations.

Geobacter species are also of interest because of their role in environmental restoration. For example, Geobacter species can destroy petroleum contaminants in polluted groundwater by oxidizing these compounds to harmless carbon dioxide. As understanding of the functioning of Geobacter species has improved it has been possible to use this information to modify environmental conditions in order to accelerate the rate of contaminant degradation. As outlined under the Bioremediation link, Geobacter species are also useful for removing radioactive metal contaminants from groundwater.

Geobacter species also have the ability to transfer electrons onto the surface of electrodes. As outlined under the Microbial Fuel Cell link, this has made it possible to design novel microbial fuel cells which can efficiently convert waste organic matter to electricity.

As outlined under the Genomics and Systems Biology link, the genomes of several Geobacter species have been sequenced and are being incorporated into a computer model that can predict Geobacter metabolism under different environmental conditions. This systems biology approach is greatly accelerating the understanding of how Geobacter species function and the optimization of bioremediation and energy harvesting applications.