Synergistic Degradation of Maize Straw Lignin by Manganese Peroxidase from Irpex lacteus.

Lignocellulose in maize straw includes cellulose, hemicellulose, and lignin, and the degradation of lignocellulose is a complex process in which multiple enzymes are jointly involved. In exploring the co-degradation of a certain substrate by multiple enzymes, different enzymes are combined freely for the achievement of the effective synergism. Additionally, some organic acids and small molecule aromatic compounds can also increase the enzymatic activity of lignin enzymes and improve the degradation rate of lignin. In this study, manganese peroxidase (MnP) from Irpex lacteus (I. lacteus) was heterologously expressed in food-grade Schizosaccharomyces pombe (S. pombe). The multiple enzymes co-fermentation conditions were initially screened by orthogonal tests: 0.5% CaCl2, 1% 10,000 U/g Laccase (Lac), 0.3% MnSO4, and 0.4% glucose oxidase (GOD). It was showed that the lignin degradation rate could reach 65.85% after 3 days of synergistic degradation with the addition of 0.02% Tween-80, 0.5 mM oxalic acid. This indicates that oxalic acid has a promoting effect on the activity of MnP, and the promoting effect is more significant when Tween-80 is complexed with oxalic acid.