Enhanced uranium immobilization from carbonate-rich water by Bacillus pasteurii via protein-induced phosphate...

Biomineralization offers a sustainable strategy for uranium (U) immobilization in contaminated water. However, carbonate generated by microbial ureolytic activity, together with proteins from microbial metabolism, severely affect uranium fixation via phosphate‑mediated biomineralization. The unrevealed interaction usually leads to unpredictable outcome of U(VI) biomineralization. Here, U(VI) biomineralization was studied using the ureolytic bacterium Bacillus pasteurii (B. pasteurii) with metabolic proteins and different prevailing ligands. Results showed that U(VI) precipitated as layered chernikovite via monodentate coordination with phosphate groups in pure B. pasteurii system. However, the urea‑derived carbonate inhibited chernikovite formation by competitively displacing phosphate ligands, instead forming a uranyl‑carbonate complex (joliotite) characterized by bidentate coordination and an extended chelate ring-a phase less suitable for long‑term U(VI) retention. Remarkably, phosphorylated proteins redirected U(VI) toward stable phosphate-based mineral phases, thereby overcoming partial carbonate-induced suppression. These proteins functioned as pre-nucleation clusters by bridging inorganic anions and U(VI), subsequently guiding biomineral diversification through combined monodentate phosphate and bidentate carbonate coordination. The insights into the enhancing role of metabolic proteins in ligand competition enable a predictive control of mineralization pathway for sustained uranium remediation in aquifers.