As sustainability and resource efficiency become global priorities, bio-based oxalic acid production has emerged as a promising innovation for the recovery of rare earth elements (REEs). A recent study published in the journal Nature Communications examined the use of the yeast Issatchenkia orientalis for oxalic acid production, a key reagent in REE leaching and extraction.
Oxalic acid. Image Credit: spline_x/Shutterstock.com
This microbial approach offers an environmentally responsible alternative to conventional chemical synthesis, reducing energy use and emissions. It supports the increasing demand for REEs, which are essential for renewable energy systems, electronics, and advanced technologies. The findings demonstrate how biotechnological processes can be integrated into mineral extraction, offering a more sustainable pathway for rare-earth recovery.
Innovations in Microbial Production of Organic Acids
The production of organic acids using microorganisms presents a sustainable alternative to traditional chemical synthesis.
Oxalic acid, a dicarboxylic acid widely used in metal leaching and textile processing, is usually produced through energy-intensive methods that rely on non-renewable resources. Biotechnological approaches convert renewable substrates into valuable compounds through microbial fermentation.
This study highlights the metabolic engineering of Issatchenkia orientalis, a yeast capable of efficiently producing oxalic acid. This organism can utilize diverse feedstocks, including agricultural and industrial waste, reducing production costs and supporting circular economy principles.
Methodological Framework for Optimizing Production
Researchers developed and optimized a bioprocess for oxalic acid production using Issatchenkia orientalis to support sustainable REE recovery. They selected I. orientalis for its ability to metabolize various carbon sources, including sugars and agricultural residues. Key pathways involved in oxalic acid biosynthesis were enhanced to improve yield.
Fermentation conditions were optimized by adjusting substrate concentration, pH (potential of hydrogen ions), temperature, and nutrient levels. The engineered strain produced 39.53 g/L of oxalic acid at pH 4.0 in fed-batch fermentation. Recovery methods, including precipitation and crystallization, were used to isolate and purify the acid efficiently. The leaching efficiency of bio-based oxalic acid on rare-earth minerals demonstrated its efficacy.
Significant Outcomes of the Research
Issatchenkia orientalis proved effective in producing oxalic acid under optimized conditions. The engineered strain achieved a concentration of 39.53 g/L, comparable to conventional chemical synthesis but with a significantly lower environmental impact. This confirms the feasibility of microbial fermentation as a viable alternative for oxalic acid production.
Beyond production efficiency, the study demonstrated that bio-based oxalic acid enhances REE recovery, with leaching experiments showing extraction rates exceeding 99 % for neodymium (Nd), dysprosium (Dy), and lanthanum (La) from individual REE chloride solutions. Economic advantages were also noted: using low-cost substrates, including agricultural by-products, reduces production costs while supporting waste valorization. The competitive production cost of $1.79/kg further strengthens the viability of this approach.
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Implications for Sustainable Mining Practices
This research has significant implications for the mining sector. The biological production of oxalic acid offers a sustainable way to enhance REE recovery, critical for electronics, renewable energy, and electric vehicles. By integrating bio-based oxalic acid into mineral processing, mining operations can reduce reliance on harsh chemical reagents, improve extraction efficiency, and lower carbon dioxide (CO2) emissions.
Improved leaching performance translates to higher recovery yields and reduced waste generation, supporting the industry’s transition toward cleaner technologies. Beyond rare earth extraction, bio-based oxalic acid has broader applications in hydrometallurgy, textile processing, agriculture, soil management, and potential roles in bioremediation.
Conclusion Future Directions
In summary, the development of bio-based oxalic acid production using Issatchenkia orientalis represents a significant advancement in sustainable mining. This approach offers an efficient, environmentally responsible pathway for rare-earth element recovery.
The study demonstrates how biotechnology can reduce reliance on energy-intensive chemical synthesis while improving extraction efficiency. As global demand for rare earth elements continues to grow, integrating microbial production systems into mining operations could strengthen supply chain sustainability and reduce environmental impact.
Future work should scale up fermentation processes, refine genetic modifications to maximize yield, and explore alternative low-cost substrates to enhance economic feasibility.
By advancing these areas, bio-based oxalic acid production can transition from the laboratory to industry. This research highlights how biotechnology can reshape traditional industries, making them more resilient and aligned with long-term sustainability goals.
Journal Reference
Lu, J., Guo, W., Dong, Z. et al. (2026). Bio-based oxalic acid production in Issatchenkia orientalis enables sustainable rare earth recovery. Nat Commun. DOI: 10.1038/s41467-026-68957-5, https://www.nature.com/articles/s41467-026-68957-5
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