An Ancient Bug Makes Electricity

Aug. 5, 2009 — -- The star of the show in Derek Lovley's lab at the University of Massachusetts is a hairy microbe that has been around since the earliest stages of life on earth, but now it has a new task. Geobacter, as the tiny bug is known, could play a leading role in removing toxic wastes and cleaning up polluted waters around the planet, but that's only part of the story.

Geobacter, it turns out, likes a hot lunch. So it produces electricity to help digest iron oxide, and therein lies an astonishing tale. It doesn't make enough power to do much other than dine on sludge and the contaminated waters of the Potomac River, where Lovley and his colleagues discovered it a couple of decades ago.

For years now Lovley, director of environmental biotechnology on the Amherst campus, has tried all sorts of sophisticated tampering, including genetic engineering, in an effort to get the bug to increase its output. The best he could get was a doubling of the current, better, but not good enough.

But recently Lovley's team practically blew their socks off when they came up with a new strain of geobacter that produces eight times the electricity of its predecessor. How did they bring that off?

They just made life a little more difficult for the bug, and it tried a whole lot harder, thus an enormous improvement in yield. By introducing a tiny "pushback" current to the microbe's environment, the bugs adapted to the new challenge, evolving the more productive strain.

The progress, described in the August issue of the journal Biosensors and Bioelectronics, moved microbial fuel cells a significant step closer to mainline electronics. A number of companies are already involved in the technology, because it could potentially solve a wide range of very different problems.

For example, "you need to put in a lot of electricity to treat waste water," Lovley said in a telephone interview, and that makes it almost impossible to clean up water resources in many areas of the world, especially Africa.

But stand back while zillions of geobacters get to work, cleaning up the water while producing enough electricity to power a light bulb or recharge a battery. Two problems, one solution.