Geobacter bacteria (Microbes, nuclear waste and power)

• With implications that could eventually benefit sites forever changed by nuclear contamination, researchers at Michigan State University have unravelled the mystery of how microbes generate electricity while cleaning up nuclear waste and other toxic metals.Details of the process, which can be improved and patented, are published in the current issue of the Proceedings of the National Academy of Sciences.
• "Geobacter bacteria are tiny micro-organisms that can play a major role in cleaning up polluted sites around the world," said Gemma Reguera, who is an MSU AgBioResearch scientist. "Uranium contamination can be produced at any step in the production of nuclear fuel, and this process safely prevents its mobility and the hazard for exposure."
• The ability of Geobacter to immobilize uranium has been well documented. However, identifying the Geobacters' conductive pili or nanowires as doing the yeoman's share of the work is a new revelation, according to a Michigan State University press release. Nanowires, hair-like appendages found on the outside of Geobacters, are the managers of electrical activity during a cleanup.

Geobacter is a genus of proteobacteria. Geobacter are an anaerobic respiration bacterial species which have capabilities that make them useful in bioremediation. The geobacter was found to be the first organism with the ability to oxidize organic compounds and metals, including iron, radioactive metals and petroleum compounds into environmentally benign carbon dioxide while using iron oxide or other available metals as electron acceptor.

Research on the potential of Geobacter is underway and on-going. Geobacter's ability to consume oil-based pollutants and radioactive material with carbon dioxide as waste byproduct has already been used in environmental clean-up for underground petroleum spills and for the precipitation of uranium out of groundwater. Geobacter metabolize the material by creating pili between itself and the food material.

It has been shown that species of Geobacter are able to cooperate in metabolizing a mixture of chemicals that neither could process alone. Provided with ethanol and sodium fumarate, G. metallireducens broke down the ethanol generating an excess of electrons which were passed to G. sulfurreducens via "nanowires" grown between the species, enabling G. sulfurreducens to break down the fumarate ions.

The production of electricity during this process has also led scientists to theorize that Geobacter could act as a natural battery. This natural battery could use renewable biomass such as compost materials, or be used to convert human and animal solid waste into electricity. There are also potential applications in the field of nanotechnology for the creation of microbial nanowires in very small circuits and electronic devices. The nanowires could also be connected, creating a microscopic power grid.