A review of bioleaching combined with low-cost fermentation and metabolic engineering technology to leach rare earth elements

Rare earth elements (REEs) are important materials for advanced technologies with a wide range of applications. Currently, most physicochemical methods for REEs extraction cause serious environmental damage. Therefore, it is critical to find safe and cost-effective techniques to effectively meet emerging demands. Among the various methods, non-contact bioleaching is being explored. This method uses microbial metabolites (mainly organic acids) to leach rare earth resources. In this process, the exploration of low-cost raw materials for biofermentation and the construction of efficient engineered strains combined with metabolic engineering technology will improve the efficiency and environmental friendliness of the method. This study reviews the organic acids used to extract REEs and emphasizes the advantages of bioleaching over other hydrometallurgical processes. It also discusses future progress and the major limitations of the approach. Based on the literature analysis, it can be concluded that the bioleaching method has great significance for extracting REEs.