嗜热拟青霉产胞外木糖苷酶发酵条件的优化

Optimization of β-xylosidase Production by Paecilomyes thermophila J18 in Liquid State Fermentation

摘要:

嗜热拟青霉J18是由本实验室筛选并保存的拟青霉新种。该菌能够利用玉米芯为碳源、尿素为氮源液体发酵高产胞外β-木糖苷酶。单因素优化试验表明：5%的粒度为0.45mm～0.9mm的玉米芯、1%尿素、初始pH 6.5、温度为45℃是最佳产酶培养条件。在优化后的条件下，培养5d产β-木糖苷酶的活力最高达3.15U/mL，比酶活为2.43U/mg。该菌所产的木聚糖酶和木糖苷酶协同作用可将桦木木聚糖完全降解成木糖，水解24h后，其水解液中还原糖含量比只加入电泳纯木聚糖酶的水解液提高了64%。

Abstract:

Paecilomyces thermophila J18 was a novel fungus isolated from soil and preserved in our lab. This strain produced a high-level extracellular β-xylosidase utilizing corncob as carbon source and urea as nitrogen source in the liquid-state fermentation. The result of single-factor-experiment revealed that 5% corncob of particle size 0.45mm～0.9mm, 1% urea, initial pH 6.5 and cultivation temperature of 45℃ were the optimal conditions for β-xylosidase production. β-xylosidase activity and specific activity were 3.15U/mL and 2.43U/mg respectively, after 5 days of cultivation in the optimized conditions. The birchwood xylan were degraded into xylose completely as the result of the synergistic action of xylanase and xylosidase from Paecilomyces thermophila J18, and the combination of xylanase and xylosidase enhance the reducing sugar yield by 64% comparing the xylanase single action after 24 h hydrolysis.