Enhanced Saccharification Efficiency of Corn Straw by Laccase-Cu2O Under Light/Dark Cycles

To strengthen the clean utilization of biomass waste, laccase modified cuprous oxide (Cu₂O) composite catalyst is synthesized. The effects of catalyst type, catalyst concentration, pH, sunlight exposure time, and lighting method on the reducing sugar yield are investigated. The composite catalyst in combination with sunlight irradiation can effectively enhance the reducing sugar yield of corn straw. The optimum conditions were pretreatment time of 55 min, catalyst concentration of 58 mg L⁻¹, pH of 5.5, enzyme hydrolysis process using a 30 DL (namely 20 min of dark/20 min of light alternating cycle for 30 h) scheme, and enzyme loading of 25 FPU g⁻¹. Validation experiments show that the lignin removal percentage can reach 95.63%, and the reducing sugar yield can reach 124.79 mg g⁻¹ under the optimum condition. The pretreatment and saccharification of straw executed twice are most advantageous for sugar production. Laccase-Cu₂O can be reused three times.