Tuesday, October 30, 2012

'Microbial Alchemy' Produces Gold From Toxic Chemical

FOCUS: 'Microbial Alchemy' Produces Gold From Toxic Chemical

***Correcting fourth paragraph to say gold is found naturally
in seawater, not gold chloride
5 October 2012, 10:18 a.m.
By Debbie Carlson
Of Kitco News http://www.kitco.com/

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(Kitco News) - The ability to create gold from base materials has eluded alchemists since the Middle Ages, but two U.S. university professors have found a way to produce small amounts of gold using metal-loving bacteria to make the magic.
By combining an artist and scientific quest, the two professors at Michigan State University found that a certain type of metal-loving bacteria can transform high amounts of the toxic chemical compound gold chloride from a liquid into solid 24-karat gold. Their method is unlikely to create a 21st century microbial gold rush as the technique is not cost-effective, one said.
“Microbial alchemy is what we’re doing,” said Kazem Kashefi, assistant professor of microbiology and molecular genetics at Michigan State University.
He and Adam Brown, associate professor of electronic art and intermedia at Michigan State, found that the bacteria, Cupriavidus metallidurans, can withstand concentrations of gold chloride 25 times higher than previously reported by scientists. Gold is found naturally in oceans, on average there is about 5 parts per million dissolved gold in seawater, Kashefi said.
In their research, the two professors used a chemostat, which is a continuous cell culture. To describe simplistically, the researchers said they took a vessel and filled it with about a liter and a half of water. The oxygen was removed and the bacteria and gold chloride were added. They kept adding gold chloride to the water to see how much the bacteria could handle, eventually stopping at 25 times higher than previously researched concentrations. In about a week, the bacteria produced about 60 milligrams of gold.
While the professors haven’t created gold out of thin air, in its liquid form gold chloride is a heavy metal and essentially useless. By using the bacteria, the two men have found a way to change the liquid into a solid, and to do it at the ambient temperature. “The bacteria are capable of breathing gold, just like people breathe oxygen,” Kashefi said.
Not having to use high heat to remove the oxygen was critical, Brown said. Boiling the water would remove the oxygen and concentrate the gold chloride, but that’s a great amount of energy used. By using bacteria, any energy used is low because the microbes do all the bio-remediation, he said.
Brown’s interest came after researching extremophiles, which are microbes that live in extreme environments, for an art project. That led him to work with Kashefi, whose research focuses micro organisms, specifically metal-reducing organisms. “I asked him, what would it take to put a gold nugget in my hand? That question had not been asked before. That’s where art leads the science,” Brown said.
His artwork using the microbes to turn chemical into gold is called “The Great Work of the Metal Lover.” In alchemy, the “magnum opus,” or great work, was the elusive quest to discover the philosopher’s stone that could turn base metals into gold, while the last name of the bacteria, Cupriavidus metallidurans, means “metal lover.”
In addition to using the living system as artwork, Brown made a series of images with a scanning electron microscope, and using the techniques to create illuminated manuscripts, he applied gold leaf to the regions of the prints where the bacterial gold deposits were found.
The artwork was selected for exhibition and received an honorable mention at the cyberart competition, Prix Ars Electronica, in Austria, where it’s on display until Oct. 7. The art installation is a portable laboratory made of 24-karat gold-plated hardware, a glass bioreactor and the bacteria, a combination that produces gold in front of an audience.
Brown said while their research proves that solid gold can be made out of the liquid gold chloride found in water, it also brings up questions. “What if we could take all the gold out of the oceans? Would we destroy the ecosystem? What economic impact would that have?” he asked.
That question may not need to be answered, as Kashefi said the method isn’t cost effective. “You would put so much money into putting in gold chloride and you’d get very little gold. But what’s interesting is to see that these bacteria can do it in their natural environment,” he said.
People’s reaction to learning about turning gold chloride into 24-karat gold has been eye-opening, Brown said. “Being involved in this project, what amazes me is that you can see people’s true colors. You can see that they’re trying to figure out how they can make gold. People see this and think they can make gold and want to get involved. It’s like a microbial gold rush. Of course, that’s the artist in me talking,” he said.
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By Debbie Carlson of Kitco News dcarlson@kitco.com
A bioreactor uses a gold-loving bacteria to turn liquid gold into usable, 24 karat gold. Photo by G.L. Kohuth, Michigan State University

Adam Brown, MSU associate professor of electronic art and intermedia. Photo by G.L. Kohuth, Michigan State University

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