Immobilized laccase in the form of (magnetic) cross-linked enzyme aggregates for sustainable diclofenac (bio)degradation

Abstract

Nowadays, major problems worldwide derive from the presence of pharmaceutically active compounds in the wastewater of hospitals and healthcare facilities. To address this issue, biological transformation of diclofenac using native and immobilized laccase is described in our study. Laccase stabilization is demonstrated, using two different types of immobilization: cross-linked enzyme aggregates (CLEAs) and magnetic cross-linked enzyme aggregates (mCLEAs). High diclofenac (DCF) removal capacity of CLEAs laccase and mCLEAs laccase in comparison to native laccase is determined. Under optimal conditions, the removal capacity of native laccase is 11.5 ± 0.3 μg DCF/glaccase, of CLEAs 15.6 ± 0.4 μg DCF/glaccase and of mCLEAs 13.6 ± 0.4 μg DCF/glaccase. Our immobilized laccase also possesses very good reusability, since the half-life of the immobilized laccase in the form of CLEAs is reached after the second cycle of biocatalyst reuse, while the half-life of the mCLEAs laccase can be detected at the fourth cycle. The improved stability of immobilized laccase in supercritical carbon dioxide (SC CO2) is shown. The promising results of DCF removal using CLEAs laccase and mCLEAs laccase show that both immobilized forms of laccase have the potential to be used in cleaner industrial technologies, e.g. wastewater treatment.