Enhanced degradation of lignin in corn stalk by combined method of Aspergillus oryzae solid state fermentation and H2O2 treatment

To shorten the time of corn stalk pretreatment and increase the degradation of lignin, solid state fermentation (SSF) with Aspegillus oryzae CGMCC5992 in the presence of H2O2 was carried out to degrade lignin in stalk. In this study, the conditions for lignin hydrolysis catalyzed by enzymes produced in SSF for 10 days were optimized by mono-factor-at-a-time design and response surface method (RSM). The removal rate of lignin increased from 30% (before hydrolysis) to 80.3% (after hydrolysis) under the temperature of 55 °C, pH 6.0, water/stalk ratio of 40, and the concentration of H2O2 at 4% (w/w). In comparison, the removal rate of lignin after 50 days of SSF only reached 57.8%. Proteomic analysis provided support for the increased lignin hydrolysis. Fermentation with A. oryzae CGMCC5992 in the presence of H2O2 increased the amount of peroxidase and intracellular catalase and decreased the amount of extracellular catalase. Therefore, the method introduced in this study can significantly shorten the time of SSF and increase the removal rate of lignin.