Immobilization of Cu2+ Based on Microbial-Induced Carbonate Precipitation by Urease-producing Strain Sporosarcina koreensis JZ-2

Abstract Microbial-induced carbonate precipitation (MICP) is an emerging bioremediation technology for heavy metals. However, the application of MICP for copper (Cu²⁺) remediation often faces challenges related to identifying robust microbial strains with high urease activity, elucidating the detailed immobilization mechanisms, and managing the ammonium by-product generated during urea hydrolysis. This study aimed to address these gaps by systematically investigating the novel ureolytic bacterium Sporosarcina koreensis Z-2 ( S. koreensis JZ-2) for Cu²⁺ immobilization. The strain exhibited strong urease activity, peaking at 3476.67 U/mL, and produced carbonate at concentrations up to 14.01 g/L. S. koreensis JZ-2 demonstrated good tolerance to Cu²⁺, with growth marginally inhibited at ≤ 20 mg/L but significantly suppressed above 50 mg/L. The optimal Cu²⁺ immobilization efficiency was 83.36% at 10 mg/L Cu²⁺. The addition of CaCl₂ synergistically enhanced the removal rate to 94.48%, while 83.72% of the co-generated ammonium was recovered via struvite (MgNH₄PO₄·6H₂O) crystallization. Mineralogical characterization confirmed that the dominant precipitates were aragonite and basic copper carbonate (Cu₂(OH)₂CO₃), clarifying the primary immobilization pathway. These findings demonstrate the integrated potential of S. koreensis JZ-2 in MICP for efficient Cu²⁺ remediation and simultaneous nutrient recovery from contaminated water.