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These Bacteria Convert Heavy Metals Into Gold

Kitco News

These Bacteria Produce Gold By Digesting Heavy Metals

(Kitco News) - While alchemy might hold the secrets to turning lead into gold or finding an elixir of immortality, a group of scientists discovered real-life magic — tiny bacteria that can convert toxic heavy metals into gold nuggets.

The phenomenon was first observed in 2009 when researchers proved that the bacterium Cupriavidus metallidurans, which is found in heavy metal-filled soil, can digest the toxic compounds and produce microscopic gold nuggets as a byproduct.

Usually, heavy metals and living organisms do not mix, yet Cupriavidus metallidurans is able to interact with copper and gold elements at a toxic level, according to the scientists, by first absorbing and then transforming them into non-poisonous forms.

Scientists said that the bacteria use an enzyme called CopA that coverts gold and copper compounds into their solid forms, which are safe to hold and even digest.

“This assures that fewer copper and gold compounds enter the cellular interior. The bacterium is poisoned less and the enzyme that pumps out the copper can dispose of the excess copper unimpeded. Another consequence: the gold compounds that are difficult to absorb transform in the outer area of the cell into harmless gold nuggets only a few nanometres in size,” said professor Dietrich H. Nies, a microbiologist at Martin Luther University Halle-Wittenberg (MLU).

“Once the metallic gold nanoparticles [are] formed in the periplasm, they are immobilized and less toxic,” Nies added.

The gold nuggets produced are just micrometers in size, which is one-millionth of a meter, according to the study.

This has great implications for future mining as this process could potentially be recreated to extract gold from ores that have a very low percentage of gold, increasing the global supply of the yellow metal as well as the ease with which it can be extracted.

The research findings were published in the Metallomics journal in January by scientists from Martin Luther University Halle-Wittenberg (MLU), the Technical University of Munich (TUM) and the University of Adelaide in Australia. 

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