Buried deep within a copper mine in Brazil, a team of scientists has uncovered a new microorganism that could transform the dangerous way that metals, like copper, are mined around the world.
This new strain of Bacillus bacteria quite literally eats copper ions for breakfast while creating highly prized and stable single-atom copper in its place, which can be used to create antimicrobial coatings for medical equipment or powering electronics like superconductors, among a multitude of other applications.
These microbes may even turn out to be multi-talented, the study’s senior author and professor of civil and environmental engineering, Debora Rodrigues, tells Inverse. Meaning that microbes burping out rare earth metals used in electronics, like lanthanum, might be just around the corner as well.
“This finding opens new doors for investigations in the biosynthesis of this and other monoatomic metals as a new green chemistry route,” says Rodrigues.
The findings were published Friday in the journal Science Advances.
What’s new — Copper, the same metal that gives a shiny, amber hue to pennies (if only on the outside) is a huge mining business across the world, with some of the largest mines residing in Chile and Peru. But the raw metals extracted from these mines are not necessarily ready for their commercial debut the moment it makes it above ground. Instead, these metals often go through a toxic synthesis process that helps convert them into more usable forms, such as single-atom copper.
“Copper has been demonstrated to kill viruses in less than 4 hours.”
The discovery in this study of an environmental microbe that can complete this synthesis process without toxic chemicals could play a huge role in promoting the safety and abundance of this type of stable copper, Rodrigues says.
“We believe this study is a breakthrough in the (green) chemistry and materials sciences fields since the currently available approaches to synthesize monoatomic metallic copper is chemically unfavorable,” she says.
“In addition, the current process to synthesize this kind of atom requires inert or reductive conditions as well the use of toxic reagents by synthetic means. In contrast, in the biosynthesis of these particles, the microorganism can produce relatively large amounts of monoatomic zero-valent copper ... quickly and easily while growing under aerobic conditions.”
Why does it matter — Having an easier and more sustainable way to process copper will send ripples through both public health and consumer products alike, says Rodrigues.
In addition to having applications in solar cells, superconductors, and even conductive ink, Rodrigues says that anti-bacterial copper coatings could also play a big role in the next pandemic.
“Engineers and environmental scientists will be able to use the copper retrieved by these microorganisms for antimicrobial processes, such as prevention of viral and bacterial infections, including prevention of the Covid-19 pandemic, by creating new coatings for masks [or] surfaces or anti-microbial products,” she says. “Copper has been demonstrated to kill viruses in less than 4 hours.”
Here’s the background — When it comes to fighting bacteria or viruses that might get us sick, copper is great at stopping many of these offenders in their tracks — punching holes through their cell walls and making it so they can’t easily mutate by destroying their DNA and RNA.
The exact reason for this property is still under investigation, but antimicrobial properties have been known for some time, even before we knew what a microbe was. Copper has been used historically by ancient Egyptians and Babylonians and is still used today in medical devices like IUDs.
What they did — To figure out whether the copper synthesis process they observed in the Brazillian mines could be reliably replicated, the team exposed the bacteria to a growth medium (essentially, a bacteria-sized swimming pool) of copper sulfate for 48 hours.
The authors write that the transformation from copper sulfate’s typical green color into amber with the introduction of the bacteria was evidence that the bacteria had successfully transformed the sulfate into just copper atoms. Rodrigues explains that these desirable copper atoms were then held “everywhere inside the bacterial cells.”
To check whether these resultant copper atoms were up to snuff with theoretical expectations of their size, the team studied 13,000 atoms under the close eye of a Transmission Electron Microscopy (a microscope that uses electrons to image extremely tiny things, like atoms.)
In addition to finding that all atoms’ size was on par with theoretical expectations, the team was also able to pin down 11 individual proteins — out of 102 unique protein found from the reaction — in the bacteria that were responsible for the “biosynthesis and stabilization” of the copper atoms.
Narrowing in on these particular proteins could help researchers better replicate this reaction on a larger scale as well, potentially even in mass production bioreactors, Rodrigues says.
What’s next — This discovery is only just the beginning of what these bacteria-created copper atoms can do, Rodrigues says. In the future, these bacteria could play an eco-friendly role in the “bioremediation of heavy metal contaminated sites” and even possibly be used to synthesize other materials as well.
“It is quite possible that they might work on other metals, including rare earth metals. It is not uncommon for microorganisms to have versatile metabolisms and to be able to biotransform more than one type of metal,” she says. “However, we have not investigated that yet.”
Abstract: The chemical synthesis of monoatomic metallic copper is unfavorable and requires inert or reductive conditions and the use of toxic reagents. Here, we report the environmental extraction and conversion of CuSO4 ions into single-atom zero-valent copper (Cu0) by a copper-resistant bacterium isolated from a copper mine in Brazil. Furthermore, the biosynthetic mechanism of Cu0 production is proposed via proteomics analysis. This microbial conversion is carried out naturally under aerobic conditions eliminating toxic solvents. One of the most advanced commercially available transmission electron microscopy systems on the market (NeoArm) was used to demonstrate the abundant intracellular synthesis of single-atom zero-valent copper by this bacterium. This finding shows that microbes in acid mine drainages can naturally extract metal ions, such as copper, and transform them into a valuable commodity.