Scientists put germs to work

Bacteria: Some microorganisms can neutralize toxic waste or generate a tiny amount of electricity.

Medicine & Science

July 26, 2004|By Robert S. Boyd | Robert S. Boyd,KNIGHT RIDDER/TRIBUNE

Geobacter, a class of bacteria, is tiny and yet so talented that it can turn deadly uranium waste into harmless muck, generate electricity from rust and garbage, and even run a toy car.

It's a lot to expect from an invisible bug less than a thousandth of an inch long. But the Energy Department, the Pentagon and the National Science Foundation are exploring the potential of geobacter and related microorganisms to perform useful work.

"Geobacter gives us a cheap and simple alternative to a cleaner, safer environment and the generation of cleaner forms of energy," said Derek Lovley, the biologist who discovered the bacteria in 1987 at the muddy bottom of the Potomac River. Lovley heads the 50-member Geobacter Project, based at the University of Massachusetts.

So far, 20 species of the geobacter genus have been recognized, plus 30 in closely related families. Scientists have identified the genes of several of these species and figured out their inner workings.

The first big job for the clever little microbes is to help clean up billions of gallons of deadly radioactive uranium waste left over from the Cold War at an old waste field in Rifle, Colo.

In the test, geobacter acts like a tiny deliveryman, shuttling electrons from atoms in a harmless organic substance, such as vinegar, to highly radioactive uranium-6. Compounds containing uranium-6 dissolve easily in water, contaminating ground water and sickening animals and people.

The addition of two new electrons reduces an atom of uranium-6 to a safer version called uranium-4, a solid material similar to natural uranium ore. It sinks to the bottom of the water, where it can be extracted or left safely in place.

Lovley called this technique "simpler, cheaper and more environmentally friendly" than digging or pumping up contaminants and trucking them elsewhere, which can take decades and cost billions of dollars.

If geobacter passes its tests, the Energy Department must decide whether and where to begin large-scale application.

Geobacter also can be used to turn toxic petroleum byproducts, such as benzene, into inoffensive carbon dioxide.

Geobacter's ability to make electricity from rust is generating interest. It removes electrons from one type of iron atom, known as Fe-2, and converts it into another form, Fe-3, the basis of ordinary rust. The electrons zip along a wire, from a positive to a negative pole, as in a miniature battery.

Lovley's lab has exploited this bit of energy to light electric bulbs, operate a calculator and power a toy car. In the future, he predicted, bacteria power could be used in less developed countries to charge batteries; run radios, TVs or computers; light a small hut. You might be able to use it at home to generate electricity from garbage, he said.

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