Cornell researchers are designing bacteria to solve problems with extracting rare earth elements from ore; the substances are vital to modern life, but their refining after extraction is expensive, harms the environment, and occurs mainly abroad.
The elements – of which there are 15 in the periodic table – are needed for everything from computers, cell phones, screens, microphones, wind turbines, electric vehicles and drivers to radar, sonar, LED lights, and rechargeable batteries.
A new study describes proof-of-principle for the engineering of a bacterium, Gluconobacter oxydans, that takes a big step towards meeting the growing demand for rare earth elements in a way that matches cost and affordability. efficiency of traditional thermochemical extraction and refining methods and is clean enough to meet US environmental standards.
“We are trying to find an environmentally friendly, low temperature, low pressure method to extract rare earth elements from a rock,” said Buz Barstow, lead author of the article and assistant professor of bioengineering. and environmental at the College of Agricultural and Life Sciences.
Alexa Schmitz, postdoctoral researcher at the Barstow laboratory, is the first author of the study “Generation of a Gluconobacter oxydans knockout collection for Improved extraction of Rare Earth Elements”, published November 18 in Nature Communications.
While the United States once refined its own rare earth elements, that production stopped more than five decades ago. However, the refinement of these elements takes place almost entirely in other countries, especially in China.
“The majority of the production and extraction of rare earth elements is in the hands of foreign countries,” said co-author Esteban Gazel, associate professor of earth and atmospheric sciences at the College of Engineering. “So for the security of our country and our way of life, we need to get back on track to control this resource. “
To meet the annual requirements of the United States for rare earth elements, approximately 71.5 million tonnes (~ 78.8 million tonnes) of raw ore would be required to extract 10,000 kilograms (~ 22,000 pounds) of the elements. .
Current methods rely on dissolving rock with hot sulfuric acid, followed by the use of organic solvents to separate very similar individual elements from each other in a solution.
“We want to find a way to create a bug that does this job better,” Barstow said.
G. oxidans is known to make an acid called a biolixiviant which dissolves rock; the bacteria use the acid to extract the phosphates from the rare earth elements. Researchers have started to manipulate the genes of G. oxidans in order to extract the elements more efficiently.
To do this, the researchers used a technology that Barstow helped develop, called Knockout Sudoku, which allowed them to turn off 2,733 genes in the G. oxidans genome one by one. The team organized mutants, each with a specific inactivated gene, so they could identify which genes play a role in extracting elements from the rock.
Schmitz identified genes involved in two systems in G. oxidans; one which slows down acidification and another which accelerates it. “We think this mutant can’t tell when it has had enough phosphate, so it continues to produce an acidic bioleacher to dissolve further,” Schmitz said. The team is also working to find ways to regulate the gene that speeds up acid production. They hope to create a system in which bacteria use cheap cellulose-derived sugars for energy.
In the study, Gazel’s lab helped develop mass spectrometry techniques with support from co-author Matt Reid, assistant professor of civil and environmental engineering, whom Schmitz used to measure concentrations of earth elements. rare from solutions where mutants have been exposed to the ore. “For some mutants, they were able to obtain very high concentrations [of rare earth elements from ore]”Gazel said.
“I am incredibly optimistic,” Gazel said. “We have a process here that will be more efficient than anything that has been done before. “
The study was funded by the Cornell Atkinson Center for Sustainability, the Cornell Energy Systems Institute, the Burroughs Welcome Fund and the Advanced Research Projects Agency-Energy.