3/16/2026 Lois Yoksoulian
Written by Lois Yoksoulian
There is a new, U.S.-based, environmentally friendly method for mining rare-earth elements used in consumer electronics, clean energy, defense and biomedical imaging. By using oxalic acid made by sugar-eating engineered yeast, the new technique can extract almost all the rare-earth elements from low-grade ore.
China currently dominates the market in both REE and oxalic acid, and orders for the conventionally produced acid can take up to six months to be fulfilled. In response to a Defense Advanced Research Projects Agency Environmental Microbes as a Bioengineering Resource solicitation, a team at Lawrence Livermore National Laboratory identified this bottleneck and discussed it with colleagues at the University of Illinois Urbana-Champaign — who have been working with engineered yeast strains to produce similar products for years — to explore potential U.S.-based bioengineered alternatives.
Additionally, conventional methods for producing oxalic acid employ other strong acids during processing, thereby generating byproducts that pose environmental challenges. “Our bio-engineered process uses the oxidizer produced from glucose, directly from the yeast organism,” said Jingxia Lu, a postdoctoral researcher at Illinois and study co-author.
The new proof-of-concept study, led by scientists from the U. of I., LLNL, and the University of Kentucky, uses the yeastIssatchenkia orientalis to produce oxalic acid and to leach REE from ore.
The study findings are published in the journal Nature Communications.
“Biomanufacturing oxalic acid by engineering the low-pH-tolerant yeast Issatchenkia orientalis greatly simplifies the process, making the entire REE recovery process potentially economically viable,” said Huimin Zhao, a professor of chemical and biomolecular engineering at the U. of I. “By leveraging our expertise in metabolic engineering of this low-pH-tolerant yeast for organic acid production, we were able to quickly create a yeast strain capable of producing more than 40 grams per liter of oxalic acid and use the fermentation broth directly for rare earth element precipitation with over 99% efficiency.”
Oxalic acid binds to rare-earth elements and selectively transforms them from a solution to a solid. In doing so, it separates them from other “junk” metals like zinc, which stay dissolved in the solution.
“What’s especially powerful about this approach is that it turns a long-standing supply-chain vulnerability into a domestic biomanufacturing opportunity,” said Yongqin Jiao at LLNL. “By coupling low-pH yeast bioproduction with selective rare earth precipitation, this work points to a scalable, sustainable pathway for REE purification.”
The team verified this process using real-world ore samples provided by the University of Kentucky and lab analyses performed at Kentucky and the U. of I.
“This step provides a crucial validation of bio-oxalic acid under realistic ore-processing conditions and establishes a strong foundation for its integration into industrial rare earth extraction and purification flowsheets,” said Rick Honaker of the University of Kentucky.
Although the researchers have demonstrated that their bio-oxalic acid is highly effective at selectively separating REE from ore, they acknowledge that the new process currently yields only a small amount of acid relative to the sugar it consumes. To make the entire process more commercially viable, the yield will need to increase. The team is currently working on improvements to do so.
“This work is a great example of what becomes possible when synthetic biology and chemical process engineering are tightly integrated,” said Dan Park at LLNL. “Illinois’ metabolic engineering expertise and LLNL’s rare earth separation and validation capabilities came together as a truly multidisciplinary team, enabling an end-to-end solution — from biological production to materials recovery.”
The DARPA Environmental Microbes as a Bioengineering Resource program supported this research. Zhao also is affiliated with bioengineering, biomedical and translational sciences and the Carl R. Woese Institute for Genomic Biology, DOE Center for Advanced Bioenergy and Bioproducts Innovation, and director of NSF Molecule Maker Lab Institute, NSF iBioFoundry, and NSF Global Center for Biofoundry Applications at Illinois.
Editor's note:
To reach Huimin Zhao, email zhao5@illinois.edu.
The paper “Bio-based oxalic acid production in Issatchenkia orientalis enables sustainable rare earth recovery“ is available online. DOI: 10.1038/s41467-026-68957-5.
Bioengineering is part of The Grainger College of Engineering at Illinois.