Metal-eating bacteria could clean up mining waste


A unique metal-eating microorganism ate a fingernail in just three days. Now they could be given a huge mission: to clean up mining waste.

In addition, the bacteria have another talent: they can make a by-product that helps to extract copper. This means that the microorganism could help to prevent mine waste in the first place.

Living on the edge: Chilean biotechnologist Nadac Reales works with creatures that can survive in extreme conditions, called extremophiles. They thrive in unusually hot or cold environments, acidic habitats, or areas of high chemical concentrations.

Extremophiles thrive in unusually hot or cold environments, acidic habitats, or areas of high chemical concentrations.

Metal-eating microbes fit this profile because, well, they eat metal, so they thrive naturally in environments with high chemical concentrations.

Reale extracted the bacteria, called Leptospirillum, from Tatio geysers in the Andes Mountains – a very acidic environment, Newsweek reports.

At first, it took a few months for the bacteria to bite a nail, which is not very practical for real applications.

So Reales tried to speed up the process.

She did this by starving the bacteria – which essentially caused them to remove as many nutrients as possible when food was available. The fastest eaters survived and reproduced. Then, as each generation of bacteria starved, they evolved to eat faster. Eventually, after a few years and several generations, the bacteria could tear off a nail in just a few days. Reales believed that this could be a viable solution to Chile’s mining waste problem.

“I realized that there were various needs in the mining industry, for example what happened with the scrap metal,” Reales told AFP.

The need for green mining: The extraction of minerals from nature frequently causes imbalances, which have a negative impact on the ecosystem. Mining can damage air and water supplies, destroy animals and their habitat, and permanently alter natural landscapes. Sinkholes, erosion, polluted waterways and deforestation are all possible consequences.

The liquid byproducts that microbes produce when they devour the metal can be used to extract copper using a method known as hydrometallurgy.

There are different types of mining pollution, depending on the type of mining, such as surface mining, brine mining or underground mining. But none of them are exempt from environmental consequences. The smelting process (applying heat to extract metal from the ore) can produce giant chunks of metal, Popular Mechanics reports. This is where Reale’s approach could prove to be successful. When Reales was looking for microbes to extract copper, she realized that the tiny bacteria could be used to clean up mining waste, which is a major source of pollution in Chile – it is the world’s largest producer of copper and the world’s second largest lithium producer. Throughout history, mining has been an important industry in Chile, generating 200,000 jobs and accounting for 12% of Chile’s GDP last year.

Additionally, the liquid byproducts that microbes produce when they devour the metal can be used to mine copper using a method known as hydrometallurgy. Typically, mining can release metal particles into the air, explosions and tunneling can weaken the soil, and mercury and other contaminants can seep into the water table. Using hydrometallurgy to extract copper could reduce these negative impacts. This would give the bacteria a dual role: cleaning up mining waste and playing an essential role in more environmentally friendly copper mining.

“We have always seen a lot of potential in this project which has already passed a major laboratory test,” microbiologist and team member Drina Vejar told Newsweek. “It is really necessary at this time when we need to plan for more sustainable development, especially in all these cities with so many polluting industries.

Eating a nail is just the start. Reale hopes that one day an army of these bacteria will make a real difference in cleaning up mine waste, consuming an entire hopper full of ore.

Reale’s company, Rudanac Biotec, strives to harness the unique talent of the bacteria and transform it into a viable product for the mining industry.

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