Study on bioleaching methods and microbial-mineral interaction of ion-adsorption type rare earth ore

Rare earth elements (REEs) are non-renewable strategic resources that are highly important for national security and development. However, the efficient and environmentally friendly mining and utilization of REEs face major challenges. Bioleaching is a clean process with the potential to replace environmentally hazardous chemical extraction methods. The present study investigated the effects of three bioleaching methods by Aspergillus niger on the extraction of ion-adsorption rare earth ore. In addition, the interaction between strain and minerals was explored by combining various characterization methods (XRD, FT-IR, Raman and SEM-EDS) and untargeted metabolomics. These findings indicated that the three-step bioleaching method was the most effective. Aspergillus niger leaches REEs through both direct action of the strain and indirect action of metabolites without destroying the mineral structure. Direct leaching (one-step and two-step methods) has been demonstrated to affect the cell morphology and structure of Aspergillus niger. Furthermore, Aspergillus niger had a certain adsorption capacity for REEs. Metabolomics analysis revealed that Aspergillus niger exhibited a regulatory response to environmental stresses during direct bioleaching, modulating tryptophan metabolism (one-step method) and the biosynthesis of secondary metabolites (two-step method). Bioleaching enables the recovery of REEs through environmentally friendly (readily biodegradable and non-toxic) metabolites produced by microbial growth, providing a green pathway for the sustainable mining of ion-adsorption rare earth ores.