Back in the Middle Ages, long before the existence of the periodic table, scientists practiced alchemy – the relentless and fruitless effort to produce gold from ordinary metals. Today, more than 600 years later, alchemy lives, thanks to special bacteria that loves to feed on a corrosive, toxic liquid called gold chloride.
In lab experiments, what starts off as a useless heavy metal is transformed almost magically, as the bacteria – called Cupriavidus metallidurans – consumes the gold chloride and excretes pure 24-karat gold nuggets.
The revelation that certain bacteria can make pure gold in this unusual way is credited to professors Kazem Kashefi and Adam Brown of Michigan State University.
“Microbial alchemy is what we’re doing,” Kashefi told Forbes magazine. “The bacteria are capable of breathing gold, just like people breathe oxygen.”
In their research, the professors took a vessel and filled it with about a liter and a half of water. Then they removed the oxygen and added the bacteria and gold chloride. Slowly, they added more and more gold chloride to the water to see how much the bacteria could process, eventually peaking at about 25 times higher than what was believed to be the limit. In about a week, the bacteria produced about 60 milligrams (.002 ounces) of gold.
Although this process has proven to work in a lab environment, it's very unlikely to be used commercially because the technique is not cost effective, according to the researchers.