耐碱性木聚糖酶产生菌的筛选及发酵条件研究

Screening of an Alkali-Tolerant Xylanase Producing Strain and Its Optimization of Enzyme Production

利用刚果红透明圈法，从造纸厂碱性土壤中筛选到一株木聚糖酶生产菌株X24—14，经培养特性研究及16SrDNA序列分析，初步认为该菌属于纤维菌属（Cellulosimicrobium）．经发酵条件优化，该菌在麸皮60g／L，蛋白胨10g／L，K2HPO47．0g/L，pH8．5，接种量为5％，37℃，200r／min的条件下发酵培养108h，可达到最大活力，为2204u／mL·该酶最适反应温度为60℃；具有较宽酌pH作用范围，在pH4．2—9．4范围内能保持较高的酶活力，在pH9．4条件下，仍具有80％的酶活力；pH稳定性较好，在4℃、pH11．0的条件下处理24h仍能保持75％的酶活力．

Using the Congo-red staining method, an alkali-tolerant xylanase producing strain X24-14 was screened from alkaline soil. It was subsequently identified as Cellulosimicrobium sp. based on its morphological characters and 16S rDNA sequence. The result of the optimized fermentation conditions showed that the maximum xylanase activity （2 204 u/mL） was achieved in the medium containing 60 g/L wheat bran, 10 g/L peptone, 7 g/L K2 HPO4, with inoeulum size 5% and 200 r/min at pH 8.5 under 37 ℃ for 108 h. The optimal temperature of the xylanase was 60 ℃. The xylanase was found with good alkali tolerance and high activity at pH range between 4.2 and 9.4. It still remained about 80% of its activity at pH 9.4 under 50 ℃. It was stable at the pH ranging from 2.0 to 11.0, still possessing 75 % of its maximal activity at pH 11 under 4℃ for 24 h.