The Midas Effect in Real Life – Bacterial Gold
Recently, scientists have discovered that certain bacteria have the ability to ‘absorb’ dissolved gold and turn it into solid, 24 carat gold. Researchers have been reporting the presence of bacteria on gold surfaces. Normally, gold is highly toxic to micro-organisms, as other heavy metals are. However, the bacterium Cupriavidus metallidurans (formerly known as Ralstonia metallidurans) is able to withstand living in surroundings that have high concentrations of heavy metals.
This discovery was first made in Australia, where the C. metallidurans was found on gold grains from two different sites in Australia which were 3500 kilometres apart. The fact that the bacteria were able to live in soil that contained high concentrations of gold alerted the researchers. The researchers were determined to find out why the bacteria would live in an environment that had high levels of gold. They isolated the bacteria in a lab and put them in a solution that contained gold. They found that the solution induced gold toxicity in the bacteria, which made them activate certain genetic clusters in order to withstand the gold toxicity. The bacteria basically detoxified the gold solution in order to survive, transforming the dissolved gold into solid, metallic gold.
It is now thought that many of the gold deposits in the world owe their existence to C. metallidurans. It has also been identified in other sites apart from Australia, including one of the biggest gold deposits in the world, the Witwaterstrand deposit in South Africa. The discovery of this bacterial mechanism has led to more understanding of how gold moves around in the environment and how certain gold deposits form.
Two scientists, Frank Reith and Gregor Grass, have developed a genetically modified version of C. metallidurans which produces a signal when the gold detoxification genes are in use. They do this by flashing a light which can be detected using a hand-held photometer. This would mean that gold prospectors would be able to take soil samples and test for gold content by adding these genetically modified bacteria to the sample.
Replacing traditional mining techniques with bacteria may not happen for a while, because the bacteria produce only small amounts of gold. But considering that gold mining is a strain on the environment because of the use of dangerous and toxic chemicals such as cyanide, there is still more research being done on C. metallidurans and its remarkable Midas effect. For now, we’ll have to stick to traditional goldmines and the recycling of scrap gold for our gold needs.
