信号肽优化提升葡萄糖氧化酶在毕赤酵母中的分泌表达水平

Glucose oxidases are of great application value in food, chemical, textile and pharmaceutical industries. In this study, the glucose oxidase (GOD) gene from Aspergillus nomius has been successfully heterologously expressed in Pichia pastoris SMD1168H. In order to obtain a recombinant GOD strain with high secretion and expression, the effects of fourteen different signal peptides on the secretion and expression of GOD in P. pastoris was evaluated. Strains with the best combinations of signal peptides were identified that enzyme activity was approximately 2.31 times than the signal peptide of GOD, with a highest level of 14.92 U mL-1 in shake flask expression. It was observed that after the scale-up fermentation in a 15 L fermentor by fed-batch, the biomass and GOD activity were significantly elevated, and the activity could be reached 108.93 U mL-1. The optimal activity of recombinant GOD was obtained at 35 C and pH 6.0, while a favorable stability at 30-35 C was presented. Furthermore, it was found that Mg2+, Mn2+, Na+, and surfactant could enhance the enzyme activity, while Sn2+, DTT, and PMSF obviously inhibited the activity of GOD. This study can provide valuable reference for the industrial production of GOD.