Abstract

Tetracycline antibiotics (TCs) are widely used in human and veterinary medicines, posing serious threats to ecological safety and public health due to their environmental persistence. Here, we heterologously expressed a laccase from Pycnoporus sanguineus (HMLac) and prepared a novel composite, copper-loaded magnetic biochar-based immobilized laccase (CuMBC@HMLac) for the removal of TCs. Compared with HMLac, CuMBC@HMLac showed enhanced stability, metal ion tolerance, and reusability. Tetracycline (TC), oxytetracycline (OTC), chlortetracycline (CTC), and doxycycline (DOX) were efficiently removed in the CuMBC@HMLac/ABTS system, and the removal efficiency was 90.57%–100% within 6 h through synergistic mechanisms involving both enzymatic catalysis and carrier adsorption. Identification of the transformation products via LC-QTOF-MS revealed that hydroxylation, deamination, oxylation, decarbonylation, hydration, demethylation, and dehydroxylation were the dominant transformation pathways of TCs. Antibacterial experiments and ECOSAR toxicity prediction confirmed good environmental safety of the CuMBC@HMLac/ABTS system. Molecular docking and free radical analysis further revealed that ABTS ·+ was a crucial factor involved in TCs removal. Overall, this study provides theoretical and technical supports for the environmental control and remediation of TCs pollution.