Speaker
Description
This study investigates the biogeochemical cycling of carbon and phosphorus during ureolysis-driven uranium immobilization in mining-impacted waters, where Bacillus pasteurii utilizes urea as a carbon/nitrogen source to generate carbonate ligands and metabolic proteins. We demonstrate that bacterially derived carbonate complexes competitively inhibit U(VI) phosphate crystallization (H₂(UO₂)₂(PO₄)₂·8H₂O) by binding to UO₂²⁺ ions ((UO₂)CO₃·2H₂O), while prolonged metabolic activity releases inorganic phosphate and phosphorylated proteins, enabling the re-precipitation of uranyl phosphate minerals. Metabolic proteins act as critical drivers of mineral maturation, solidifying pre-nucleation clusters into hybrid organic-inorganic crystalline phases via scaffolding effects. Density functional theory (DFT) simulations quantitatively resolve a urea-dependent coordination shift: UO₂²⁺ transitions from an initial 5-coordinate configuration (bound to HPO₄²⁻, membrane -COOH, and PO₄³⁻ groups) to a 6-coordinate state after 8 h ureolysis, dominated by tridentate carbonate ligation yet retaining trace PO₄³⁻/-COOH coordination, confirming ligand substitution-driven expansion of the uranyl coordination sphere. These results elucidate how microbial C/P cycling and secretory proteins synergistically regulate uranium biomineralization dynamics, offering novel strategies for targeted uranium sequestration in carbonate-rich wastewaters.