Alkalitalea saponilacus产木聚糖酶的碳源优化及酶学特性

Carbon source optimization and characterization of a xylanase from Alkalitalea saponilacus SC/BZ-SP2T

摘要:

[目的]确定厌氧盐碱细菌Alkalitalea saponilacus产木聚糖酶所需的碳源，优化木聚糖粗酶的提取条件并分析酶学性质。[方法]应用GC技术分析A.saponilacus发酵木聚糖的主要产物；利用二硝基水杨酸法（DNS）测定木聚糖酶活力以获得最优的碳源、提取粗酶的最佳条件及其酶学特性。[结果]A.saponilacus以不同来源木聚糖为底物时，发酵产生的主要产物丙酸含量都在80%以上。若以0.4%（W/V）蔗糖+0.1%（W/V）桦木木聚糖为复合碳源时，木聚糖酶活力是以桦木木聚糖或者蔗糖为单一碳源时的3.2倍。木聚糖酶的酶活力在盐度2%-6%、pH 7.0和55达到最佳且在该条件下的酶活力为590 IU/mg。此外，该酶活力在0.2% Tween 20存在时增加，而在5 mmol/L Mg²⁺和0.2% Triton X-100存在时无显著影响，但在Cu²⁺、Fe³⁺和Ni²⁺等金属离子存在时则被显著抑制。[结论]A.saponilacus发酵主产物丙酸以及生物合成的木聚糖酶在工业生产中具有广泛的应用前景。

Abstract:

[Objective] We optimized carbon source for xylanase production by anaerobically halophilic alkaliphilic bacterium Alkalitalea saponilacus and characterized the enzyme.[Methods] Xylanase activity was determined by 2-nitro salicylic acid (DNS) method. The conditions for the extraction of crude xylanase were optimized and the enzyme was characterized.[Results] Xylanase activity by fermentation using 0.4% (W/V) sucrose+0.1% (W/V) birch xylan as carbon source was 3.2 folds higher than that with single substrate of birch xylan or sucrose. The maximal xylanase activity reached 590 IU/mg under the conditions of salinity between 2% and 6%, pH 7.0 and 55℃. Enzyme activity was significantly inhibited with Cu²⁺, Fe³⁺and Ni²⁺.[Conclusion] Xylanase produced by A. saponilacus can have potential for industrial production.