"Mining" bacteria turn toxic copper ions into useful metal

"Mining" bacteria turn toxic copper ions into useful metal
Researchers have isolated a bacterium that can convert toxic forms of copper into useable metallic copper
Researchers have isolated a bacterium that can convert toxic forms of copper into useable metallic copper
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Researchers have isolated a bacterium that can convert toxic forms of copper into useable metallic copper
Researchers have isolated a bacterium that can convert toxic forms of copper into useable metallic copper

Copper is one of the most widely used metals, but extracting and refining it into a useful form can be energy intensive and requires harsh chemical treatments. But now, researchers at the University of Houston have discovered bacteria that naturally convert toxic copper ions into metallic copper.

No matter how inhospitable an environment seems to us, chances are high that some form of life will find a way to thrive there. Copper mines are one such example – copper ores can be toxic – but certain species of bacteria have been found living there. And in the new study, researchers investigated what they’re actually doing in these mines.

Using an electron microscope, the team examined a species of Bacillus that had been isolated from a copper mine in Brazil. They found that the bacteria were able to survive by converting toxic copper sulfate ions into a stable, single-atom form known as zero-valent copper. This is the handy metallic copper that we’re most familiar with.

“The microbes utilize a unique biological pathway with an array of proteins that can extract copper (II) (Cu2+) and convert it into single-atom zero-valent copper (Cu0),” says Debora Rodrigues, co-author of the study. “The aim of the microbes is to create a less toxic environment for themselves by converting the ionic copper into single-atom copper, but at the same time they make something that is beneficial for us too.”

This find is particularly interesting because our own industrial processes for this conversion are quite environmentally unfriendly, requiring toxic solvents and producing dangerous gases like sulfur dioxide. It’s also labor intensive and can be expensive, the team says.

“In terms of chemistry, this is extremely difficult to derive,” says Francisco Robles Hernandez, co-author of the study. “Typically, harsh chemicals are used in order to produce single atoms of any element. This bacterium is creating it naturally, that is very impressive.”

Harnessing bacteria to convert copper into useful forms could end up being safer and more efficient, the team says, and they could allow mines to extract valuable materials from waste streams, such as acid mine drainages. Other species might be performing similar functions too – after all, other bacteria have been found to convert toxic metals into tiny gold nuggets.

However, as usual, there’s the question of just how scalable the process might be for industrial use. The next steps in the study will be to investigate that aspect, and harvest the copper from the bacteria.

The research was published in the journal Science Advances.

Source: University of Houston

Chris Coles
having once worked to remover ten slabs of copper from a 40 foot freight container that had, during heavy weather, slipped out of the top container in the hold of a container ship ricocheted off ballast pipes at the bottom, into the bottom containers, and thus have some idea of what bulk copper looks like, it will take a truly massive quantity of such bacteria to produce ~40 tons of copper, and that was just one container load . . .
To counter Chris Cole's comment, even if it's not used to produce tons of copper, it could be very useful for cleaning copper out of the environment. It doesn't take much copper leaching out of a tailings pile to harm life around it. If this technique could trap the toxic waste and produce some usable copper, that's better than just temporarily trapping the toxins.
Carlos Robles

You are underestimating the potential of bacteria. You can find tens, if not hundreds, of patents in the field. The process is 100% commercial and as TechGazer says tailings are very toxic, just treating the tailings justify the research. This bacteria survives the acidity and other toxic environments such as cyanide that is very common in copper mining to collect gold. Imagine that you have a mountain of tailings (typical in any mine) and you add the bacteria on the surface, then thousands of feet (or meters) below you make a collection system for the bacteria. Arguably, to saturate the mountain with bacteria, you may need to invest and spend days or months. But once it is saturated, you will have a constant yield for years producing at a decent peace. It may not compete with hydrometallurgical processes, but in copper mining people say that if you save 1 penny per ton of mineral extracted, you are millionaire at the end of the day. Not at the end of the week or at the end of the month or the year, only one day. So 40 tons is nothing compared to what you can do and people do in many countries to mine copper using different methods including bacteria. Just for curiosity, I suggest you to look at the size of a copper mine. You could make a city and locate hundreds of thousand of people if not millions in and out of it. Next time you have a container with 40 tons of copper use a crane because this bacteria unfortunately does not eat copper, eats sulfates (including coper). Yet, it was possible that your 40 tons were mined with bacteria.