Nature: Gold that is dissolved in solution is toxic to many species of bacteria. However, two species have been found that convert the dissolved gold into inert nanoparticles. One of the bacteria species creates the nanoparticles internally, while the other, Delftia acidovarans, deposits them externally. A team of researchers led by Nathan Magarvey of McMaster University in Hamilton, Canada, has determined the set of genes and the chemical metabolite responsible. The researchers engineered the bacteria to remove the genes they thought were involved and found that the bacteria’s growth was significantly stunted. They believe the genes were responsible for creating a chemical—which they dubbed delftibactin—that caused the gold to precipitate out of solution and for pushing the gold out of the cell. Magarvey says there may be other mechanisms involved as well. The researchers believe that delftibactin or the bacteria themselves could be used to produce gold nanoparticles industrially or to precipitate gold out of wastewater from mines.