It will take years before bacteria can generate enough energy to generate electricity for transportation, homes or businesses, but researchers at the University of Minnesota studying bacteria have found a way to convert waste into electricity. They've discovered that riboflavin (also known as vitamin B-2) is responsible for much of the energy produced by a bacteria named Shewanella, which is commonly found throughout aquatic environments from the Arctic to the Antarctic. As said one of the researchers, '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.' But read more...
The Shewanella oneidensis is well known. You can see above an "AFM topograph of the metal reducing bacterium Shewanella oneidensis strain MR-1 cultivated under electron acceptor limitation to induce the production of electrically conductive appendages known as bacterial nanowires" (Credit: M. El-Naggar, USC and Y. Gorby, J. Craig Venter Institute, via this page on Asylum Research website, a company developing atomic force microscopes).
It's the third time that this Shewanella oneidensis appears on my blog. Here are the links to two previous posts, "Bacteria can build nanowires" (July 11, 2006) and "Cleaning uranium waste with bacteria" (August 12, 2006).
Now, let's go back to the researchers involved in this project. They include assistant professor in the Department of Microbiology, Daniel Bond and the members of his lab, and Jeffrey Gralnick and the members of assistant professor in the Department of Microbiology his lab.
But how these bacteria produce electricity? "In nature, bacteria such as Shewanella need to access and dissolve metals such as iron. Having the ability to direct electrons to metals allows them to change their chemistry and availability. 'Bacteria have been changing the chemistry of the environment for billions of years,' said Gralnick. 'Their ability to make iron soluble is key to metal cycling in the environment and essential to most life on earth.'"
This research work has been published as an open access article in the March 3 issue of the Proceedings of the National Academy of Sciences under the name "Shewanella secretes flavins that mediate extracellular electron transfer." Here is the beginning of the abstract. "Bacteria able to transfer electrons to metals are key agents in biogeochemical metal cycling, subsurface bioremediation, and corrosion processes. More recently, these bacteria have gained attention as the transfer of electrons from the cell surface to conductive materials can be used in multiple applications. 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."
For more information, here is a link to the full article (PDF format, 6 pages, 915 KB).
Sources: University of Minnesota news release, March 3, 2008; and various websites
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