Expression of Pleurotus ostreatus Laccase Gene in Pichia pastoris and Its Degradation of Corn Stover Lignin

Pleurotus ostreatus is a species of white-rot fungi that effectively degrades lignin. In this study, we aimed to efficiently express the lac-2 gene of Pleurotus ostreatus in the Pichia pastoris X33 yeast strain. The enzymatic properties of recombinant yeast were determined, and its ability to degrade corn stover lignin was determined. The results showed the optimum pH values of recombinant laccase for 2,2'-Azinobis-3-ethylbenzothiazoline-6-sulfonic acid, 2,6-dimethoxyphenol, and 2-methoxyphenol were 3.0, 3.0, and 3.5, respectively. The optimum reaction temperature was 50 degrees C, and it had good thermal stability and acid and alkali resistance. The degradation rate of lignin in corn stover by recombinant laccase was 18.36%, and the native Pleurotus ostreatus degradation rate was 14.05%, the difference between them is significant (p < 0.05). This experiment lays a foundation for the study of the degradation mechanism of lignin by laccase.