Uranium immobilization by Brevundimonas vesicularis LWG1: A synergistic approach via biomineralization, biosorption, and bioreduction

With the growing demand for uranium (U) resources, the development of efficient and economical methods for treating U mine wastewater is critical for environmental and human health protection. Biomineralization of stable U phosphate minerals offers a promising remedial approach. In this study, Brevundimonas vesicularis strain LWG1, a U-resistant bacterium capable of secreting phosphatase, was isolated from real U mine wastewater. LWG1 achieved over 90 % U removal at concentrations exceeding 100 μM and maintained high performance across varying U concentrations, biomass dosages, bicarbonate levels, pH values, and in real U mine wastewater. Its exceptional efficiency was due to the synergetic effect of biomineralization, biosorption and bioreduction. Phosphatase secretion of LWG1 promoted extracellular precipitation of U-phosphate minerals such as metanatroautunite, as evidenced by X-ray diffraction (XRD) and high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM). Fourier transform infrared spectroscopy (FTIR) revealed that biosorption was facilitated by functional groups (carboxyl, hydroxyl/amine, phosphate) on the cell surface. X-ray photoelectron spectroscopy (XPS) indicated partial reduction of U(VI) to U(IV) by LWG1, likely facilitated by localized reductive environments and mediated by reducing metabolites. Importantly, non-targeted metabolomics analysis further revealed significant metabolic adjustments related to phosphate metabolism, membrane restructuring, and redox activity, supporting the involvement of the three U immobilization pathways. Altogether, this study demonstrates the remarkable U removal capacity of LWG1 and provides mechanistic insights to support its application in U wastewater bioremediation.