When thinking of a gold prospector, most of us conjure up a wizened old character leading a mule that carries his pick, gold pan, and rusty coffee pot. Nowadays, think of bacteria instead. Specifically, picture the bacterium Cupriavidus metallidurans (formerly Ralstonia metallidurans), which carries out the biomineralization of gold. It transforms toxic gold compounds into their metallic form via an active mechanism.
The leader of a large international research group working on this subject, Frank Reith of the University of Adelaide, explains: A number of years ago we discovered that the metal-resistant bacterium Cupriavidus metallidurans occurred on gold grains from two sites in Australia. The sites are 3500 km apart, in southern New South Wales and northern Queensland, so when we found the same organism on grains from both sites we thought we were onto something. It made us wonder why these organisms live in this particular environment. The results of this study point to their involvement in the active detoxification of Au complexes leading to formation of gold biominerals.(Science News)