Overexpression of the endo-inulinase gene from two different sources and characteristics analysis

Abstract

The endo-inulinase genes from Aspergillus niger (A. niger) TCCC41064 and Penicillium sp. TN-88 were inserted into the expression vector pPIC9 K. The recombinant plasmids were subsequently transformed into P. pastoris GS115 by electroporation, respectively. The two recombinants (P. pastoris GS115/pPIC9 K-inuA, GS115/pPIC9 K-inuC) were purified and characterized. The molecular weight of the purified inuA and inuC were both about 66.2 kDa. The specific activity of transformant endo-inulinase inuA and inuC were 13.5 and 69.3 U/mL. The optimal pH and temperature were 5.0, 60 °C for inuA, and 4.0, 50 °C, respectively. InuA, 83.2% of the residual enzymatic activity at 55 °C for 9 h. Meanwhile, inuC retained 75.4% at 40 °C for 9 h. The purified inuC converts inulin into trisaccharide (74.8%) and for the inuA was 36.7%. The researches on inulinase will provide a better engineering strain for designing the industrial biocatalyst.