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Researchers Find Mechanism for Bacterial Production of Electricity
4 March 2008
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| Combined electron shuttling and chelator (shelator) activity by FMN or riboflavin (abbreviated as vitamin B2). |
Researchers at the University of Minnesota that are studying bacteria that are able to transfer electrons to metals have discovered that riboflavin (commonly known as vitamin B2) is responsible for much of the energy produced by these organisms.
The bacteria, Shewanella, are commonly found in water and soil and are of interest because they can convert simple organic compounds such as lactic acid into electricity, according to Daniel Bond and Jeffrey Gralnick of the University of Minnesota’s BioTechnology Institute and department of microbiology, who led the research effort.
This is very exciting because it solves a fundamental biological puzzle. Scientists have known for years that Shewanella produce electricity. Now we know how they do it.
—Daniel Bond
The interdisciplinary research team, which included several students, showed that bacteria growing on electrodes naturally produced riboflavin. Because riboflavin was able to carry electrons from the living cells to the electrodes, rates of electricity production increased by 370% as riboflavin accumulated.
In this work, we adapted electrochemical techniques to probe intact biofilms of Shewanella oneidensis MR-1 and Shewanella sp. MR-4 grown by using a poised electrode as an electron acceptor. This approach detected redox-active molecules within biofilms, which were involved in electron transfer to the electrode. A combination of methods identified a mixture of riboflavin and riboflavin-5’-phosphate in supernatants from biofilm reactors, with riboflavin representing the dominant component during sustained incubations (>72 h). Removal of riboflavin from biofilms reduced the rate of electron transfer to electrodes by >70%, consistent with a role as a soluble redox shuttle carrying electrons from the cell surface to external acceptors.
The discovery means Shewanella can produce more power simply by increased riboflavin levels. Also, the finding opens up multiple possibilities for innovations in renewable energy and environmental clean-up. The research is published as an open access article in the 3 March issue of the Proceedings of the National Academy of Sciences.
Scaled-up microbial fuel cells using similar bacteria could generate enough electricity to clean up wastewater or power remote sensors on the ocean floor. But more ambitious applications, such as electricity for transportation, homes or businesses, will require significant advances in biology and in the cost-effectiveness of fuel cell materials.
Bacteria have been changing the chemistry of the environment for billions of years. Their ability to make iron soluble is key to metal cycling in the environment and essential to most life on earth.
—Jeffrey Gralnick
The process could be reversed to prevent corrosion of iron and other metals on ships. Bond and Gralnick were each recently awarded funding from the US Navy to explore this and other potential applications.
This research was funded by the Initiative for Renewable Energy and the Environment, the National Science Foundation, the National Institutes of Health and Cargill. The university’s BioTechnology Institute is co-sponsored by the College of Biological Sciences and the Institute of Technology.
Resources
Enrico Marsili, Daniel B. Baron, Indraneel D. Shikhare, Dan Coursolle, Jeffrey A. Gralnick, and Daniel R. Bond. Shewanella secretes flavins that mediate extracellular electron transfer. PNAS published March 3, 2008, 10.1073/pnas.0710525105
March 4, 2008 in Biotech, Power Generation | Permalink | Comments (2) | TrackBack (0)
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Comments
What advancement! Let's hope that some of those big scientific ambitions are not that far away.
Also, do you know of any copyright or patents on these findings? I am a big believer in open source; it would be a shame to lose progress due to red tape.
z
Posted by: zoe | Mar 4, 2008 11:09:27 AM
A lot of University work is patented but available for license at a reasonable fee. If you look at most Universities, they have Technology Transfer centers that are there to assist the private sector in gaining license rights very easily at a fair price.
Posted by: sjc | Mar 6, 2008 10:42:37 AM
