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Microbes on the march
When it comes to releasing metals from sulphides, the mining industry has no older and more willing ally than an army of humble bacteria. Chris Morrissey looks at the potential for biotechnology in extracting copper...

Noise is an anathema to the modern mining industry. Noise means wasted energy, and in looking for better ways of winning metals, the industry is increasingly using techniques that involve biological processes. Its most powerful ally is the smallest and most silent of all lifeforms - bacteria.

In using bacteria to extract metals from rocks, miners are taking a leaf out of Nature's book. Bacteria have been doing it since the dawn of life - producing enzymes that speed up the oxidation of mineral sulphides and release their heavy metals into solution.

Prospectors have always recognized the significance of red rivers - rios tintos in Spanish - stained by metals that have been fixed by algae. They use them to find what they call gossans, the rusty outcrops of decomposing sulphide deposits. Inside the gossans, helping the decomposition along, are invisible menageries of hungry bacteria with tongue twisting names like Thiobacillus thiooxidans and Leptospirillum ferrooxidans.

It was not until the early 1950s that the importance of bacteria as natural sulphide destroyers became clear. Since then, many different types with the talent have been identified, with varying tolerances and biochemical roles. Individuals of the most voracious type are a few thousandths of a millimetre in size, rod shaped and able to move around.



Microbes on the march When it comes to releasing metals from sulphides, the mining industry has no older and more willing ally than an army of humble bacteria. Chris Morrissey looks at the potential for biotechnology in extracting copper... Noise is an anathema to the modern mining industry. Noise means wasted energy, and in looking for better ways of winning metals, the industry is increasingly using techniques that involve biological processes. Its most powerful ally is the smallest and most silent of all lifeforms - bacteria. In using bacteria to extract metals from rocks, miners are taking a leaf out of Nature's book. Bacteria have been doing it since the dawn of life - producing enzymes that speed up the oxidation of mineral sulphides and release their heavy metals into solution. Prospectors have always recognized the significance of red rivers - rios tintos in Spanish - stained by metals that have been fixed by algae. They use them to find what they call gossans, the rusty outcrops of decomposing sulphide deposits. Inside the gossans, helping the decomposition along, are invisible menageries of hungry bacteria with tongue twisting names like Thiobacillus thiooxidans and Leptospirillum ferrooxidans. It was not until the early 1950s that the importance of bacteria as natural sulphide destroyers became clear. Since then, many different types with the talent have been identified, with varying tolerances and biochemical roles. Individuals of the most voracious type are a few thousandths of a millimetre in size, rod shaped and able to move around.
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