Scalable and Consolidated Microbial Platform for Rare Earth Element Leaching and Recovery from Waste Sources

Area of Science:

• Biotechnology
• Environmental Science
• Materials Science

Background:

• Traditional rare earth element (REE) extraction is energy-intensive, hazardous, and environmentally damaging.
• Existing biobased methods often use extremophiles and share similar detrimental effects.
• Methylobacterium extorquens AM1 can utilize REEs from electronic waste for its metabolic processes.

Purpose of the Study:

• To develop a scalable and sustainable bioleaching method for REE recovery from electronic waste.
• To investigate and engineer mechanisms for enhanced REE bioaccumulation in M. extorquens.
• To demonstrate the potential of M. extorquens as a versatile platform for critical metal recovery.

Main Methods:

• Cultivating Methylobacterium extorquens AM1 using electronic waste as the sole REE source in scalable bioreactors (up to 10 L).
• Investigating the effects of organic acids on REE leaching and engineered overproduction of lanthanophores and pyrroloquinoline quinone for specific bioleaching.
• Employing genetic engineering to modify exopolyphosphatase activity to enhance intracellular REE accumulation.

Main Results:

• Scalable (10 L) REE recovery from electronic waste using M. extorquens without harsh chemicals or high temperatures, achieving consistent yields.
• Engineered REE-specific bioleaching and highly specific, concentration-dependent bioaccumulation.
• Demonstrated increased REE accumulation through genetic modification of phosphate metabolism and successful growth using pulverized smartphones.

Conclusions:

• Methylobacterium extorquens offers a scalable, environmentally friendly platform for recovering critical rare earth elements from diverse electronic waste sources.
• Engineered enhancements in ligand production and phosphate metabolism significantly improve REE bioaccumulation efficiency.
• This biological approach presents a sustainable alternative to conventional chemical extraction methods for critical metals.