Derek Lovley has done it again. He and his lab at the University of Massachusetts- Amherst have isolated yet another extraordinary microbe. As seems to be the theme of his work, his discovery not only serves to advance the field of microbiology but also serves to the betterment of humanity. This strange new bacterium, Rhodoferax ferrireducens, is capable of reducing normal sugars while at the same time efficiently producing a continuous, usable electrical current.
He and his team found R. ferrireducens eighteen feet deep in the mud at the bottom of Oyster Bay, Virginia. To no surprise, this deep dwelling microbe was found to be a very hardy pyschrotolerant anaerobe (Scholz). When grown in cultures, it thrived in a strict anaerobic environment at approximately 25oC. Nonetheless, R. ferrireducens still showed significant growth at temperatures as low as 4oC, hence pyschrotolerant and not psychrophilic. Cultures were grown in a neutral medium with lactate as the electron source (R. ferrireducens). Later, it was found that a wide range of sugars could be substituted for lactate to produce the same results. These included sucrose, fructose, glucose, acetate, and xylose; and it is speculated that the list of energy sources could be much broader (Touchette).
The most exciting part of R. ferrireducens is not what it consumes though, but instead what it produces. Rather than reducing oxygen as aerobic microbes do, it transfers its electrons to iron (III) and other minerals in its environment (Direct Electricity). This last statement can be applied to many different iron-reducing bacteria; the catch with R. ferrireducens is that it does it with such efficiency. Over 80% of the electrons in its oxidized sugar are transferred directly to the iron “anode” on which it is attached. Compare this with a measly 1-3% efficiency by previously-studied similar bacteria (Touchette). Although the process is slow, it steadily produces a viable current capable of charging batteries or running low-pull electrical devices. Scientists are currently working on ways to further optimize the process so that R. ferrireducens’s electicity producing power may be fully realized (Scholz).
With the world predicted to run out of fossil fuels within the next fifty years, new energy sources are a major concern. After further optimization, this seemingly unlimited microbial power source may be the most economical option in the future. Already the military is looking into microbe full cells capable of powering small remote devices for very long periods of time. In addition, the dairy industry is considering R. ferrireducens as a way to get rid of its waste lactose while making a little extra money on the side. These and other promising applications may make R. ferrireducens Derek Lovley’s most noteworthy discovery. (Direct Electricity)
References:
Scholz, Fritz, et. al., “Bacterial batteries.” Nature Biotechnology October 2003: 1151-1152.
Lovley, Derek. “R. ferrireducens.” International Journal of Systematic and Evolutionary Microbiology 2003: 669-673.
Touchette, Nancy. Bacterial Batteries Yield Sweet Success. 8 September 2003. <http://www.genomenewsnetwork.org/articles/09_03/battery.shtml>.
Lovley, Derek et. al. Direct Electricity Generation from Carbohydrates in Mediatorless Microbial Fuel Cells. 2004 < http://amherst.cvip-umass.net/index.cfm?fuseaction=tech. 20102&item_id=576>
*Disclaimer - This report was written by a student participaring in a microbiology course at the Missouri University of Science and Technology. The accuracy of the contents of this report is not guaranteed and it is recommended that you seek additional sources of information to verify the contents.
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