A species of bacterium forms tiny nuggets of gold to combat the toxic effects of the dissolved form of the element.

The bacterium Delftia acidovorans lives in extensive communities — known as biofilms — that coat gold nuggets. A team led by Nathan Magarvey at McMaster University in Hamilton, Ontario, exposed the microbe to a gold solution and discovered that gold particles formed outside the bacterial membrane. Genomic and biochemical analysis revealed that the microbe secretes a peptide, called delftibactin, that binds to gold ions to form gold particles. Strains in which the genes involved in producing delftibactin were inactivated showed decreased growth in the presence of soluble gold, suggesting that the peptide detoxifies gold ions.

Nature Chem. Biol. http://dx.doi.org/10.1038/nchembio.1179 (2013)