For most organisms, complex gold salts in combination with copper ions are poison. The bacterium Cupriavidus metallidurans is capable of reducing toxic Au(I/III)-complexes into metallic gold (Au) nano-particles, thereby mediating the (trans)formation of Au nuggets in Earth surface environments. The metallophilic bacterium C. metallidurans can live in the presence of a mixture of toxic transition metal ions, which occur also in auriferous soils. In a recent study, a group of German and Australian biologists described a molecular mechanism that provides such unusual properties for a bacterium, and identified a key enzyme. Due to these molecular mechanisms and key enzyme, this permits C. metallidurans to thrive in Au-rich environments and biomineralise metallic Au.
These are the "invisible heroes"!