The Research Of Fusing The Xylanase XynⅢ From Aspergillus Niger To The Thermophilic Glucanase From Thermotoga Maritima

Xylanase is the enzyme family that dehydrates xylan into xylose oroligoxylose.Xylanase has extensive applications in the industries of feed,food,fabric and papermaking. This study chose the gene, xyn which encoding the mature protein of an endo-β-1,4-xylanase XynⅢobtained from Aspergillus niger A-25. it’s optimum temperature is 47℃and optimum pH is 3.8, But it doesn’t work well in the extreme environments such as highly acidic or highly alkalic.This study chose the other gene is glu, which encoding the mature protein of an thermophilic endoglucanase obtained from Thermotoga maritime.The glucanase’s optimum temperature is beyond 90℃.In this research,we has fused the thermophilic glucanase from Thermotoga maritime to the xylanase from Aspergillus niger, and then overexpressed in Escherichia coli BL21(DE3).We obtained recombinant proteins Glu-Xyn and Xyn-Glu. Then we investigate the characterizations of the recombinant proteins.(1) The optimal pH of XynⅢ、Xyn-Glu and Glu-Xyn’s xylanase are 3.8. The optimal temperature of XynⅢ、Xyn-Glu and Glu-Xyn’s xylanase are 47℃、50℃and 47℃respectively. After keeping 30min at 50℃, the relative activity of Xyn-Glu’s xylanase and XynⅢare 60% and 40%, but the relative activity of Glu-Xyn’s xylanase is almost 0.(2) The optimal pH of Glu、Xyn-GLU and Glu-Xyn’s glucanase are 3.8、3.8 and 5.8 respectively. The glucanase of Xyn-Glu and Glu-Xyn are stabler than Glu to temperture, especially Xyn-Glu. The optimal temperature of Glu、Xyn-Glu and Glu-Xyn’s glucanase are more than 96℃.