Synthetic biology-enabled green production of rare earth elements

Rare earth elements (REEs) play an irreplaceable strategic role in emerging materials, energy technologies, and national defense. However, conventional hydrometallurgical processes rely on strong acids, strong bases, and organic solvents, leading to high energy consumption and severe environmental pollution. The development of synthetic biology has opened new avenues for green REE manufacturing. This review systematically summarizes the mechanisms by which microorganisms and biomacromolecules participate in REE leaching, enrichment and fine separation, and highlights recent advances in synthetic-biology-driven REE biomanufacturing: (i) rewiring microbial metabolic pathways to achieve efficient REE leaching; (ii) engineering or displaying functional moieties on cell surfaces to enhance the selectivity and loading capacity of bioadsorbents; and (iii) biosynthesizing REE-binding proteins that enable fine separation of REEs in fully aqueous systems. Compared with conventional chemical processes, REE biomanufacturing offers shorter process chains, lower energy consumption, and high programmability, but still faces challenges such as limited production throughput, insufficient selectivity, and inadequate stability of chassis cells. By constructing and screening efficient synthetic biology tools, optimizing engineered chassis strains, and integrating continuous and automated process control, REE biomanufacturing is expected to evolve into a green, cost-effective, and scalable technology for industrial applications.