Tiny Bacterium Turns Heavy Metal into Gold
Cupriavidus metallidurans, a bacterium found in soil rich in toxic elements, can absorb compounds rich in toxic metals and extract gold from them, producing tiny gold nuggets. The bacterium has evolved to need copper to survive and can activate a special enzyme, called CupA, which can pump out all the excess copper and keep the bacterium healthy. When gold is present, the CupA is made inactive and a different enzyme, CopA, is made active, which transforms the copper and gold compounds into forms that are difficult to absorb, resulting in harmless gold nuggets only a few nanometres in size.