"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. ... 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. " Kazem Kashefi, assistant professor of microbiology and molecular genetics at Michigan State University 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.
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http://www.forbes.com/sites/kitconews/2012/10/05/focus-microbial-alchemy-produces-gold-from-toxic-chemical/