Homologous constitutive expression of Xyn III in Trichoderma reesei QM9414 and its characterization.

Xylanase III (Xyn III), a specific endoxylanase that belongs to family 10 of the glycoside hydrolases, was overexpressed in Trichoderma reesei QM9414 using a constitutive strong promoter of the gene encoding pyruvate decarboxylase (pdc). The maximum recombinant xylanase activity achieved was 817.2 ± 65.2 U/mL in the transformant fermentation liquid. The productivities of Xyn III accounted for approximately 53% of the total protein secreted by the recombinant. The enzyme was optimally active at 60 °C and pH 6. The recombinant Xyn III was stable at pH 5-8. This is the first report on the homologous expression of xyn3 in T. reesei QM9414. The properties of Xyn III make it promising in a variety of industrial use.