Magnetic Ganoderma lucidum spore microspheres: A novel material to immobilize CotA multicopper oxidase for dye decolorization

In this study, hollow microspheres were obtained from Ganoderma lucidum spores. Then the hollow microspheres were loaded with Fe₃O₄ nanoparticles to prepare novel magnetic spore microspheres. TEM images and X-ray diffractometry demonstrated that the Fe₃O₄ nanoparticles were incorporated throughout the spore microsphere. CotA multicopper oxidase was chosen as biomacromolecule to study the loading ability of the magnetic spore microspheres. The combination of the CotA enzyme with the microsphere was observed by laser scanning confocal microscope. The loaded amount of CotA on the microspheres was 75 mg/g when the CotA concentration was 1.2 mg/mL and the activity recovery of the immobilized CotA was 81%. The magnetic microspheres loaded with CotA, which can be easily and quickly recovered by an external magnetic field, were used for dye decolorization. After 1 h decolorization, 99% of the indigo carmine has been removed by 10 mg microspheres. In addition, the immobilized CotA retained 75% of activity after 10 consecutive cycles, which indicated that the magnetic spore microspheres are good support material for immobilization of the enzyme.