Occurring with associated minerals in the Earth’s crust, lanthanum is one of the most important members of the lanthanides that share similar physicochemical properties and have a variety of industrial applications. Aspergillus niger is widely used in industrial fermentations due to its production of multiple secondary metabolites including enzymes and organic acids. It is a ubiquitous soil inhabitant, and since it produces geoactive agents such as citric and oxalic acid, it can play a role in the biotransformation of metal-containing minerals. The aim of this project was to explore the mechanisms and factors involved in the interactions between lanthanum and oxalate-producing strains of A. niger. As shown in previous studies, A. niger has significant properties of mineral solubilization and secondary mineral formation, many of them being precipitated as metal oxalates. However, there is little or no information on the possible formation of lanthanum oxalates mediated by fungi. In this study, fungal growth under conditions of lanthanum stress was investigated, and it was found that crystalline deposits were formed around fungal colonies in the presence of LaCl3. The biogenic crystals were recovered and subjected to examination for their elemental composition, morphological features and mineral phases using energy dispersive X-ray analysis (EDXA), scanning electron microscopy (SEM) and X-ray crystallography (XRD) respectively. These confirmed the production of lanthanum oxalate (La2(C2O4)3·xH2O). This work sheds light on lanthanum-A. niger interactions and potential applications in biorecovery of this precious element.
Full conference title:
- MS 2017