Gold prospectors may one day use Petri dishes to help with their quests. A species of bacterium forms nanoscale gold nuggets to help it to grow in toxic solutions of the precious metal, reports a paper published online today in Nature Chemical Biology.
The molecule with which the bacteria create the particles could one day be used to collect gold from mine waste, says Frank Reith, an environmental microbiologist at the University of Adelaide in Australia, who works on gold-processing bacteria but was not involved in the latest study.
Reith found some of the first convincing evidence that bacteria thrive on gold particles about ten years ago. At multiple sites, thousands of kilometers apart, he and his team found the bacterium Cupriavidus metallidurans living in biofilms on gold nuggets. The bacteria detoxify dissolved gold by accumulating it in inert nanoparticles inside their cells; Reith and his colleagues have spent the past decade working out how, but have not yet published their complete conclusions.
Some biofilms also contained a second species of bacterium: Delftia acidovarans. Nathan Magarvey, a biochemist at McMaster University in Hamilton, Canada, and his team grew this species in the presence of a gold solution and discovered that the bacterial colonies were surrounded by dark haloes of gold nanoparticles. The researchers concluded that D. acidovarans was somehow creating gold particles outside its cell wall, instead of inside as C. metallidurans does.