Utilization of Aspergillus niger strain to leach rare earth elements based on untargeted metabolomics analysis

With the continuous improvement in technology, the potential of rare earth elements (REEs) is constantly being tapped. Some of these REEs are valuable additives in the high-tech field. Bioleaching is an effective and clean method for extracting REEs from ion-adsorption type rare earth ore. In this study, the effect of non-contact bioleaching of REEs by Aspergillus niger strain was investigated, and the optimal culture conditions of strain and the optimal leaching conditions of rare earth ore were investigated. In addition, untargeted metabolomics was used to explore the differential metabolites produced by the strain before and after leaching and to verify the metabolites affected during leaching. The results showed that the REEs leaching efficiency was indeed improved by changing the temperature, pH, shaking speed and liquid–solid ratio. Metabolomic experiments showed that organic acids and their derivatives played important roles, and most of them were down-regulated after leaching.