Gene Cloning And Characterization Of Xylanase And Mannanase

β-Xylanases andβ-Mannanases are endo-wise glycosyl hydrolase, they catalyzes random hydrolysis ofβ-1,4-xylosidic linkages or (3-1,4-mannosidic linkages respectively. They have been widely used in many industry processes, such as foodstuff, animal feed, paper energy and environmental protection.In this panper, we use genetic engineering technology to study the gene clonging, over expressing and enzyme properties of the Xylanase from Streptomyces megasporus DSM 41476 and mannase from Streptomyces fradiae var. k11. The results are as follows:1. Using the degenerate primer PCR and TAIL-PCR methods, there genes were obtained. They are aβ-Mannanase gene (mans221) from Streptomyces fradiae k11 and two xylanase genes (xynM4 and xynM6) from Streptomyces megasporus DSM 41476. Based on homology searches in GenBank using BLAST and multiple alignments, the sequences of the nucleotides of the three genes shared highest identities of were 68%,53% and 66% respectively. The results suggest that some of them are novel.2. The recombinant ManS221, which was expressed in Escherichia coli BL21 (DE3), showed the optimal condition were pH 6.0,52℃, and retained stable over pH4.0-10.0 and 45～60℃. ManS221 was also highly resistant to various neutral proteases. The recombinant XynM4 and XynM6 expressed in Pichia pastoris showed the optimal condition were pH 6.0,5.5 and 57℃,70℃, respectively. The 86% of XynM4's hydrolysis product of xylan was xylobiose. XynM6 have good thermophile.It retained more than 60% of the maximum activity when assayed at 50～80℃. In brewery industry, XynM6 reduced the turbidity and viscosity of mash evidently.In this study, we are promising in applications of constructing the commercialized high-volume withdrawal strains and molecular biological research on enzymy.