Gold producing bacteria

King Midas is remembered in Greek mythology for his ability to turn objects he touched into gold. Surprisingly, his strange ability is shared in reality by a certain species of bacteria called Cupriavidus metallidurans.

Cupriavidus metallidurans strain CH34 (renamed from Ralstonia metallidurans and previously known as Ralstonia eutropha and Alcaligenes eutrophus) is a nonspore-forming, Gram-negative bacterium which is adapted to survive several forms of heavy metal stress. Therefore, it is an ideal subject to study heavy metal disturbance of cellular processes. This bacterium shows a unique combination of advantages not present in this form in other bacteria.

This bacterium extracts gold from heavy metal compounds in the environment, forming tiny gold nano-nuggets. A team of researchers from Germany and Australia led by Frank Reith from the University of Adelaide and Dietrich H. Nies from Martin-Luther-Universistat Halle-Wittenberg identified the enzymes involved in this “gold cycle,” and reported their findings in the journal Metallomics.

C. metallidurans is normally found in industrial sediments or wastes which contain high heavy metal concentrations. C. metallidurans was initially isolated from the wastewater of a zinc factory in Liège, Belgium. Later, this bacterium was found in another unusual place; it was the dominant organism present in biofilms on gold grains found in the Prophet gold mine in Queensland, Australia.

C. metallidurans—whose name means “metal-enduring”—is a unique species of bacteria that survives in environments with high heavy metal concentrations, which would be toxic to other bacteria. C. metallidurans is often found in industrial waste sites or mining locations, and especially in gold nuggets in Australia.

To read more, see Biotechniques

Posted by Dr. Tim Sandle