Heavy metal contamination poses persistent risks owing to metal mobility and bioavailability. In this study, we explored a biological strategy for altering the fate of metal ions by engineering the yeast Yarrowia lipolytica to secrete alkaline phosphatase (PhoX), thereby driving enzymatic metal-phosphate precipitation. Through copy number optimization and process refinement, a recombinant strain was obtained harboring three copies of phoX , exhibiting high extracellular PhoX activity (136.67 U/mL), and it showed a broad-spectrum precipitation of metal ions, including Cd 2+ , Mn 2+ , Co 2+ , Cr 3+ , Cu 2+ , Ni 2+ and Pb 2+ . A two-step process was then designed, achieving near-quantitative removal efficiencies (>90%) for Cd 2+ , Mn 2+ , Co 2+ , Cr 3+ , and Pb 2+ (ranging from 90.92% to 99.28%), while Cu 2+ (89.09%) and Ni 2+ (78.35%) showed slightly lower efficiencies. The system also achieved high removal capacities of up to 1251.64 mg Cd 2+ /g biomass. Microscopic and crystallographic analyses confirmed the formation of cell-associated, crystalline metal phosphate minerals, with Co 2+ immobilized as Co 3 (PO 4 ) 2 ·8H 2 O. By utilizing a generally recognized as safe microorganism to convert soluble, bioavailable metals into stable mineral phases, we elucidated a biologically mediated immobilization pathway that can reduce metal toxicity and mobility, offering a sustainable mechanism for remediating metal-contaminated environments.
