Immobilization of cellulase on a core-shell structured metal-organic framework composites: Better inhibitors tolerance and easier recycling

For the first time, cellulase was successfully immobilized on a magnetic core-shell metal-organic framework (MOF) material, UIO-66-NH₂. The as-prepared immobilized cellulase demonstrated a high protein loading efficiency of 126.2 g/g support and a high enzyme activity recovery of 78.4%. Cellulase immobilized on magnetic UIO-66-NH₂ exhibited a superior performance in terms of pH stability, thermal stability and catalytic efficiency compared to its free form. Notably, immobilized cellulase could be recycled for up to 5 consecutive runs. Furthermore, compared to free cellulase, immobilized cellulase showed better tolerance to formic acid and vanillin, two typical inhibitors found in lignocellulosic prehydrolysates. In the presence of 5 g/L of formic acid and vanillin, immobilized cellulase demonstrated 16.8% and 21.5% higher activity than free enzyme, respectively, and its improvement in hydrolysis yield was 18.7% and 19.6% respectively. This is firstly confirmed that immobilization can alleviate the inhibitory effects of certain pretreatment inhibitors on cellulase.