An Ancient Bug Makes Electricity

It's a lofty new role for a microbe that has remained basically unchanged for billions of years. Lovley's early research, published in Nature in 1987, revealed that geobacter was the force behind the creation of magnetite, an important iron ore that is strongly attracted by a magnet. It was formed in rocks deposited billions of years ago, so geobacter was in on the ground floor.

"It's very likely that microbes growing on iron may have been the first form of life on earth," Lovley said. All this praise for a bug that isn't much to look at. Geobacter is covered with tiny hairs, 20,000 times finer than a human hair, called pili. The hairs are quite strong, and apparently play a key role in the microbe's ability to produce an electric current.

That fact is well known to hundreds of students who have built their own little microbial generator for a science fair. Stick an electrode into slime containing a whole bunch of geobacters, and electrons flow to the anode and can be easily measured.

Geobacter has had that ability throughout it's lifetime, but it's doubtful that it knew it. It had never seen an electrode, but apparently iron oxide fulfilled that function.

Unknown Potential

And over the course of billions of years, it probably had never seen a "pushback" current. Yet it knew what to do - turn up the juice and make Lovley a very happy man.

"Each step along the way has been astonishing," he said. "We started out just trying to understand the processes" by which geobacter devoured the sediments in the Potomac River. "But then we found that geobacter could grow on a variety of radioactive and toxic metals, like uranium."

That has led to a "technically simple and quite inexpensive strategy for cleaning up a lot of contaminated sites."

And that would have been enough to mark this research very successful, but then Lovley pushed geobacter a little harder, making it swim upstream, at least electronically.

It came through like a trooper, and this is still just the beginning.

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