Enhanced stability and reusability of metagenomic laccase via immobilization on functionalized mesoporous silica for antibiotic contaminant removal

The extensive application of tetracycline antibiotics in agriculture and medicine has led to persistent contamination of aquatic and terrestrial ecosystems, disrupting microbial communities and contributing to the spread of antibiotic resistance. Conventional treatment methods often suffer from poor efficiency, limited stability, and high environmental costs, underscoring the need for robust and sustainable alternatives. Here, we present a biocatalytic platform in which a metagenome-derived laccase (PersiLac1) is covalently immobilized onto imidazole-functionalized SBA-15 mesoporous silica to overcome the limitations of free laccase, including low stability and high leaching. Immobilization markedly enhanced thermal stability, reusability, and catalytic efficiency toward the degradation of doxycycline (DC) and tetracycline (TC). The optimized system exhibited minimal enzyme leaching (9.6% at 25 °C; 22.0% at 80 °C) and achieved removal efficiencies of 76.7 ± 2.8% for DC and 53.7 ± 2.1% for TC within 24 h. High removal performance was maintained even at elevated antibiotic concentrations (200 mg L⁻¹), with 43.9% and 42.8% removal for DC and TC, respectively. The immobilized laccase retained over 83% (DC) and 73% (TC) of its initial activity after 10 consecutive reuse cycles. To the best of our knowledge, this is the first report of integrating a metagenomic laccase with an imidazole-functionalized SBA-15 support for antibiotic degradation, offering a unique combination of enhanced stability, high reusability, and environmentally relevant performance. These findings highlight the potential of this immobilization strategy as a sustainable and high-performance solution for the remediation of antibiotic contaminants in water systems.