Copper ions binding regulation for the high-efficiency biodegradation of ciprofloxacin and tetracycline-HCl by low-cost permeabilized-cells

Cu2+ plays a decisive role for the bio-oxidation in the active center of laccase. In the fermentation-purified process, the loss of Cu2+ reduces the activity and the high cost limits the application of laccase. In this study, a fermentation-permeabilization combined process were developed which based on the regulation of Cu2+ binding time to produce the permeabilized-cells containing laccase, in which Cu2+ can enter the cells freely to greatly improve the laccase activity and reduce the immobilization cost by about 19 times. So, the permeabilized-cells is suitable for biodegradation of antibiotic pollution in the environment, which was applied for the biodegradation of ciprofloxacin (CIP) and tetracycline-HCl (TCH) and the degradation efficiency reached 95.42% and 98.73%, respectively, with low ecotoxicity of the degradation products. Finally, the degradation mechanism was analyzed theoretically by molecular docking. Therefore, this study provided a low-cost, eco-friendly, and widely applicable method for organic pollutants removal.