2024-09-21 19:13:28
The bacteria that defecates gold
In an environment that could be deadly for most living beings, C. metallidurans has developed a mechanism that allows it to survive and, as a consequence, generates the expulsion of gold nuggetsresearchers revealed in a study published in the journal Metallomics.
“Apart from toxic heavy metals, the living conditions in these soils are not bad. There is enough hydrogen to conserve energy and there is almost no competition. If an organism decides to survive here, it has to find a way to protect itself from these toxic substances,” the microbiologist explained. Dietrich H. Niesfrom the Martin Luther University of Halle-Wittenberg.
From various studies, it was discovered that C. metallidurans has a protection mechanism which, in addition to gold, also includes copper. The microorganism’s cells allow the compounds to enter. Once the metals are inside, various enzymes intervene, which, after an ingenious process, culminate in the expulsion of the gold particles.
Bacteria play a major role in the formation of gold nuggets in Australia. Photo: CSIRO
To gather evidence, the international team of scientists conducted experiments with C. metallidurans in the European Synchrotron Radiation Facility (ESRF). He observed how the bacteria reacted to toxic gold complexes in a solution prepared in the laboratory.
“The results of this study point to their involvement in the active detoxification of Au (gold) complexes, leading to the formation of gold biominerals,” said Frank Reith, leader of the research, in an official ESRF statement.
According to experts, this discovery provides important information that in the future could allow the gold production from minerals that contain a small amount of this element, without the need for the intervention of other toxic bonds, such as mercury, which was previously used.
How are metals transformed into gold?
After several years of research, Reith and his team are able to describe the mechanism by which Cupriavidus metallidurans transforms toxic metals from its environment into gold.
To do this, it must be taken into account that copper is a vital element for bacteria, but it is toxic when present in large quantities. Also, this component, together with gold (in its contaminated version), are easier to absorb and reach the interior of the microorganism.
So when too much copper builds up inside the bacteria, an enzyme called copper is activated inside the bacteria. Cupwhich pumps the metals out. However, another enzyme known as CopA which transforms compounds into forms that are more difficult to absorb.
In this way, C. metallidurans ensures that it reduces the poisoning it is exposed to, while releasing the gold nuggets after the process of transforming the toxic metals. According to Niels, each of the particles produced is just a few nanometres in size.