Abstract: A strain of Aspergillus fumigates with high activity towards Dioscorea zingiberensis saponins was isolated, and the characteristics of its β-glucosidase were studied preliminarily. As shown in the results, the β-glucosidase from Aspergillus fumigates which effectively produced diosgenin from saponins, exhibited the high level of activity and stablity at high temperature. At 65℃ and pH6.0, the β-Glucosidase activity of Aspergillus fumigates was 4.1 U/mg, and it retained 77% of its original activity for 48 hours with 1.5 mol/L ammonium sulfate. The β-Glucosidase of this Aspergillus fumigates hydrolyzed the D-glucose at the C-3position in trillin to yield saponin, and the transformation ratio was 56% within 24 hours.

Key words: Aspergillus fumigates, β-glucosidase, trillin, diosgenin

摘要： 为实现黄姜皂苷的清洁生产, 从自来水中筛选能用于黄姜皂苷生物转化的微生物并研究其粗酶的性质。首先通过平板划线法分离自来水中能水解黄姜皂苷的微生物, 利用TLC法和HPLC法分析微生物的转化效率。然后采用比色法测定粗酶β-糖苷酶活性的最佳反应条件并检验其热稳定性。最后以典型螺甾烷型皂苷延龄草苷为底物, 探讨该粗酶用于黄姜皂苷生物转化的可能性。筛选所得最佳菌种为烟曲霉, 其粗酶在65℃ pH6.0条件下活力为4.1 U/mg, 为筛选所得另外两种真菌的2.7倍和2.6倍; 含有1.5 mol/L硫酸铵时, 其粗酶活性在65℃放置48小时后还剩余77%; 该酶对延龄草苷的水解反应在24小时达到平衡, 皂素的得率达56%。首次报道了烟曲霉及其粗酶对黄姜皂苷的生物转化, 其粗酶的热稳定性远高于其他耐热性β-糖苷酶, 且对延龄草苷的转化率较高。

关键词: 烟曲霉, β-糖苷酶, 延龄草苷, 皂素