Gold-digging bacteria could be high-tech miners

Biochemistry and gold prospecting may have more in common than one might think. A species of bacterium has been identified that can survive in toxic solutions of gold, forming microscopic particles of the precious mineral.

The bacterium -- Delftia acidovarans (D. acidovarans) -- possesses a molecule that extracts and condenses minute pieces of gold. The molecule could one day be used to collect gold from mine waste.

In a study published in Nature Chemical Biology, a team led by Nathan Magarvey, a biochemist at McMaster University in Hamilton, Canada, analyzed D. acidovarans in a gold solution and observed dark halos surrounding the bacteria. The halos were nanoparticles of gold.

Researchers used genome analysis to pinpoint a chemical metabolite and set of genes that were responsible for the halo. They also engineered bacteria lacking those genes, and found that its growth was stunted and no halos formed. The team then isolated a chemical produced by the unengineered bacteria and were able to form gold particles out of a solution. Researchers named the chemical delftibactin.

Researchers suggest D. acidovarans may use this chemical to keep metal from entering its cells.

Frank Reith, a microbiologist at the University of Adelaide in Australia, whose work on gold-processing bacteria was a touchstone for Magarvey's team, told Nature, "The idea could be to use a bacterium or metabolite to seed these waste-drop piles, leave them standing for years, and see if bigger particles form."

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