Biomineralization of gold: Biofilms on bacterioform gold

Abstract

<jats:p> Bacterial biofilms are associated with secondary gold grains from two sites in Australia. 16 <jats:italic>S</jats:italic> ribosomal DNA clones of the genus <jats:italic>Ralstonia</jats:italic> that bear 99% similarity to the bacterium <jats:italic>Ralstonia metallidurans</jats:italic> —shown to precipitate gold from aqueous gold(III) tetrachloride—were present on all DNA-positive gold grains but were not detected in the surrounding soils. These results provide evidence for the bacterial contribution to the authigenic formation of secondary bacterioform gold grains and nuggets. </jats:p>