The synergistic effect of lignin peroxidase and cellulase in Aspergillus oryzae solid‐state fermentation substrate on enzyme‐catalyzed oxidative degradation of lignin

Abstract

AbstractBACKGROUNDWe have reported the oxidative degradation of lignin catalyzed by lignin peroxidase (LiP) from Aspergillus oxyzae broth in previous studies. The aim of the present paper is to obtain the maximal yield of total reducing sugar (Ytrs) by synergistic effect analysis between LiP and three components of cellulase (endo‐β‐1,4‐glucanase, exo‐β‐1,4‐glucanase and β‐glucosidase).RESULTSThe Michaelis–Menten analogous model was applied to fit experimental data of lignin oxidative degradation. The apparent Michaelis constant of purified LiP product (3.02 mg mL–1) was lower than that of the crude LiP solution (4.74 mg mL−1), and the apparent maximum reaction rate of the purified LiP product (1.15 mg mL−1 h−1) was higher than that of the crude LiP solution (0.86 mg mL−1 h−1). The maximum Ytrs (49.794%) was obtained when the β‐glucosidase activity was 0; the activities of LiP, endo‐β‐1,4‐glucanase and exo‐β‐1,4‐glucanase were 10.77, 3.360 and 3.427 U mL−1 (3:1:1), respectively. The components and structure of the substrate was extremely different before and after synergistic action under optimal conditions.CONCLUSIONA synergistic effect exists between LiP and cellulase. β‐glucosidase is the key enzyme that inhibits the oxidative degradation of lignin. The results lay the foundation for screening and optimizing fermentation process conditions of the LiP strain, and improving the efficiency of enzyme‐catalyzed oxidative degradation of lignin. © 2018 Society of Chemical Industry