Expression ofβ-Glucanase Gene eglA6 of Aspergillus niger in Kluyveromyces lactis and Characterization of Recombinant Enzyme

Abstract:

This study aimed to express gene eglA6 from Aspergillus niger, which encoding a highly thermal stable β-glucanase in Kluyveromyces lactis(K. Lactis), and investigated the properties of recombinant enzyme. The recombinant strain K. Lactis GG799/pKLAC1-eglA6 SL105 expressing β-glucanase was constructed by using the K. Lactis expression system with an enzyme activity of 23.0 U/mL in shake flask. The apparent molecular weight of recombinant enzyme AnEglA6k was 5.6×10⁴, which was significantly higher than those of the same gene in Pichia pastoris. The optimum pH of AnEglA6K was 5.0 and the optimum temperature was 75 ℃. The half-life of AnEglA6K was 65.0 min at 80 ℃. The specific activity of AnEglA6K was about 0.5 U/mL with Avicel as substrate. The expression products of eglA6 in K. lactis and Pichia pastoris were significantly different. The molecular weight of product expressed by eglA6 in K. lactis was significantly higher than that in Pichia pastoris, and the thermal stability and crystalline cellulose degradation activity of product expressed by eglA6 in K. lactis were also higher than those in Pichia pastoris. The recombinant glucanase derived from the expression of eglA6 gene by K. lactis has high thermostability and is suitable for application in feed industry.