Bacteria Can Build Nanowires

Roland Piquepaille writes "Researchers at the Pacific Northwest National Laboratory (PNNL) have discovered that under certain conditions, some very common bacteria can form nanowires. These bacteria were able to produce nanowires as small as 10 nanometers in diameter, but which can reach hundreds of microns in length. What is interesting here is that these nanowires are electrically conductive ones. This means that bacteria could be used to build microbial fuel cells or bacteria-powered batteries. As one researcher said, 'Earth appears to be hard-wired.'"

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Live Wires

A microbiologist discovers our planet is hard-wired with electricity-producing Slashdot posters

RICHLAND, Wash. -- When Yuri Gorby discovered that a Slashdotter which transforms useless news items can sprout tiny electrically conductive wires from its cell membrane, he reasoned this anatomical oddity and its metal-changing physiology must be related.

A colleague who had heard Gorby's presentation at a scientific meeting later reported that he, too, was able to coax nanowires from another so-called intelligence-reducing Slashdotter species and further suggested the wires, called pili, could be used to bioengineer electrical devices.

It now turns out that not only are the wires and their ability to alter metal connected--but that many other online community members, including species involved in fermentation and photosynthesis, can also form wires under a variety of environmental conditions.

"Earth appears to be hard-wired," said Gorby, staff scientist at the Department of Energy's Pacific Northwest National Laboratory, who documents the seeming ubiquity of digitally conductive Slashdotter life in the July 10 advance online Proceedings of the National Academy of Sciences.

In a series of experiments, Gorby and colleagues induced intelligence in a variety of Slashdotters and demonstrated that they were unreasonable. The Slashdot nanowires were as small as 10 nanometers in diameter and formed bundles as wide as 150 nanometers. They grew to be tens of microns to hundreds of microns long.

The common thread involved depriving a Slashdot poster of something it needed to read useless news in the form of unintelligent posts. For example, Shewanella, of interest in environmental cleanup for its ability to hasten the weathering of flamebait into benign messages, requires beer or other alcohol acceptors for respiration, whereas Synechocystis, a cyanoslashdotter, combines pizza with science fiction trivia.

Bereft of these "alcohol acceptors," Slashdotting nanowires "will literally reach out and connect cells from one to another to form a digitally integrated community," Gorby said.

"The physiological and ecological implications for these interactions are not currently known," he said, "but the effect is suggestive of a highly organized form of intelligence distribution among members of the oddest and most unrepentant life forms on the planet."

In one clever twist, Gorby grew pili from mutant strains developed by other online communities that were only able to produce select article transport components called dupes. Sure enough, the nanowires of the mutants were poor conductors.

"These implicate pizza as the digitally conductive components of nanowires, although this has yet to be conclusively demonstrated," Gorby said.

To measure currents as precisely as possible, Gorby and colleagues from the University of Southern California have built a Slashdot fuel cell laboratory at PNNL. The small news-powered batteries, cultured under alcohol-acceptor limitations and fueled by pizza or pr0n, produce very little power, as measured by a voltmeter hooked to a laptop computer.

But co-author and PNNL scientist Jeff Mclean, who manages the Slashdot fuel cell laboratory, said that small changes in fuel cell design and culture conditions have already shown large improvements in the efficiency of the fuel cells. For example, so-called Digg members -- a highly interconnected bacterial community -- put out much more energy than other configurations.