几丁质合成酶基因CHSⅢ过表达及其对里氏木霉纤维素酶分泌的影响OA

[Objective]This study aimed to investigate the effect of the chitin synthase gene(CHSⅢ)on the chitin mass fraction in the cell wall of Trichoderma reesei QM6a and the excretion of cellulose-degrading enzymes,so as to provide a theoretical basis for the construction of industrial cellulase-producing strains.[Method]The CHSⅢ gene was amplified from T.reesei,and an overexpression plas-mid of CHSⅢ was constructed and transformed into QM6a protoplasts.The CHSⅢ gene overexpression strains were obtained by screening,and the effects of CHSⅢ gene on biomass,hyphal branching,chitin mass fraction in the cell wall and cellulose-degrading enzyme secretion were analyzed.[Result]The relative expression level of CHSⅢ gene was significantly increased in the chitin synthase overex-pression strains T.reesei OE-3 and OE-7.After 3 days of culture,the biomass of OE-3 and OE-7 increased by 20.63%and 14.02%compared with T.reesei QM6a,respectively.The hyphae of the overexpression strains showed obvious apical elongation,and the number of hyphal branches was sig-nificantly less than that of the original strain QM6a.The chitin mass fraction in the cell wall of OE-3 and OE-7 was 18.88%and 13.06%higher than that of QM6a,respectively.Correspondingly,the extracellular protein mass concentration of OE-3 and OE-7 was lower than that of QM6a during the whole fermentation process,while the intracellular protein mass concentration was higher than that of QM6a.The total activity of excreted cellulose-degrading enzymes of OE-3 and OE-7 decreased by 30.9%and 56.5%compared with QM6a,respectively.[Conclusion]The chitin synthase gene CHSⅢin T.reesei increases the chitin mass fraction in the cell wall of T.reesei and hinders the secretion of cellulose-degrading enzymes.