Miniscule single cells of bacteria are the masters of our world. They play many different roles in life on earth, with one of the most surprising being that some of them can actually purify precious metals.
An international team of researchers have discovered that a particular species of bacteria, Cupriavidus metallidurans, can actually ingest toxic metallic compounds and still thrive. What’s more is that the bacteria can actually produce tiny gold nuggets as a side-effect.
Gold moves through a process that’s called the biogeochemical cycle, just as many other earth elements do. This process sees elements being dissolved, shifted around and eventually re-concentrated in the Earth’s sediment.
Seeing as microbes are involved at every step of this process, scientists have long wondered how the microbes don’t get poisoned by the highly toxic compounds formed by gold ions in the soil.
Cupriavidus metallidurans, which is a rod-shaped bacteria species, was first found to excrete gold nuggets back in 2009 when scientists discovered that it’s capable of ingesting toxic gold compounds and converting them into the element’s metallic form without endangering or harming itself.
After many years of investigation, scientists now know how the bacteria are capable of this amazing feat. It thrives in soils containing both hydrogen and a range of toxic heavy metals, meaning that it has little to no competition from other organisms that would easily be poisoned in such an environment.
This means that any organism choosing to live in such an environment has to have a way of protecting itself from all of the toxicity surrounding it. It turns out that this particular bacterium has an ingenious protective mechanism that involves both gold and copper.
Compounds containing both of these elements can easily be ingested by the bacteria, and copper ions and gold complexes get transported deep inside. Then, the bacteria use enzymes to shift offending metals out of their cells, allowing them to dispose of them unimpeded. Not only does this process allow the bacteria to shed all of the unwanted copper – It also results in tiny gold nugget nanoparticles on its surface.
The new research that has resulted in these findings builds on previous research conducted by the same team is a fascinating insight into the weird talents of this particular bacteria, which could potentially be put to good use.
The significance of the findings is that scientists are now a huge step closer to unlocking the biogeochemical cycle of gold. Understanding this process could lead to gold refining from ores that only contain very small amounts of the precious metal, which is something that’s extremely tricky to do at present.
