Microbes have Midas touch

NewScientist.com

Biologists have long observed that bacteria such as Cupriavidus metallidurans are associated with gold-rich deposits. And researchers have recently discovered why. They found that dissolved gold is harmful to the bacterium's metabolism, so it produces enzymes to convert the toxic gold compounds in soil into metallic gold particles.

With some genetic manipulation, these bacteria can be engineered into gold detectors. When added to soil samples, they could give off a visible signal when their gold-detox genes are switched on, indicating that there's gold in them there samples.