Using Bacteria to Dig for Gold
Today, gold miners use mercury to bind gold and extract it from hard-to-access places. But the metal is toxic, and so, scientists are searching for a new method for extracting the hard-to-access gold. And now, they might have found a solution.
The C. metallidurans bacterium has found its own way of handling heavy metals, enabling it to live in places from which other organisms keep away. Without competition from other microbes, it thrives in soil layers that are rich in heavy metals. Unlike other bacteria, C. metalli
durans has a faculty for getting rid of the metals, so they will not accumulate in the organism.
Scientists from Germany and Australia have found out, how it is done. It's all thanks to a complex interaction between the bacterium’s special enzymes and the metals of copper and gold.
Like other creatures, the bacterium needs the copper to survive, but in large quantities, the metal is toxic. When a certain quantity of copper has entered the bacterium, it will pump it out again by means of a special enzyme. But if gold atoms are also present, the bacteria react differently. The gold and copper combination is more toxic than the individual metals, so another enzyme takes over, changing the way in which the metals behave, so they become less toxic and are prevented from entering deeply into the bacterium. Instead, the copper is immediately pumped out, taking the gold with it. In the process, the gold is accumulated into tiny, extractable lumps on the surface of the bacterium.