Expression of an alkali-tolerant xylanase gene in Pichia pastoris and its enzymatic characterization
In this study,xylanase gene (xynAeSC) from Streptomyces chartreusis L1105 without carbohydrate binding domain (CBD) was cloned into expression vector.Recombinant strain (GS115-3-20) was fermented under the optimal condition for enzyme production.The yield of xylanase enzyme was up to 683 ± 9 U/mL.Results showed that recombinant xylanase had the high relative enzyme activity at pH 6.2 ～ 8.6,especially at 7.2.It had the relative activity more than 70％ at 40 ～ 60 ℃2.The optimal temperature was around 70 ℃.It also showed the highest specific activity towards Oat-speh xylan (equal to 259.7％ ± 10.7％ of relative activity towards Birch xylan).It also showed the lowest activity towards sugar cane pulp xylan (only equal to 16.0％ ± 1.5％ of relative activity towards Birch xylan).Its activity and properties had not significantly affected by removing CBD domain.All these study made this expression system attractive for industrial applications.
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