产β-葡萄糖苷酶酵母菌的分离鉴定及其在人参皂苷Rg3转化中的应用

Screening and Identification of β-Glucosidase-Producing Yeast and Its Application in the Bioconversion of Ginsenoside Rg3

筛选产β-葡萄糖苷酶的微生物及其在转化人参皂苷Rg3中的应用。kefir粒发酵人参后,采用改良七叶苷琼脂培养基筛选产β-葡萄糖苷酶的微生物,并结合菌落形态以及26S rDNA D1/D2区核酸序列鉴定。结果发现1株在七叶苷琼脂培养基上呈黑色水解斑的微生物,经分子生物学鉴定,该菌种为马克斯克鲁维酵母(Kluyveromyces marxianus)。在单因素试验基础上,应用Box-Behnken设计原理,设计人参-水质量比、发酵时间、接种量3因素3水平响应面试验,优化马克斯克鲁维酵母发酵人参,转化人参皂苷Rg3的发酵条件,建立回归模型。优化后的发酵条件为人参-水质量比1∶2.65、接种量2.94%、发酵时间3 d,该条件下人参皂苷Rg3含量为3.31 mg/g,转化率为248%。该结论为全组分人参发酵食品工业化生产提供理论数据。

The objective of this study was to isolate a microorganism capable of producing β-glucosidase to transform ginsenoside Rg3. A modified esculin agar medium was used to the strain from kefir fermented ginseng slurry and this strain produced black hydrolysis spots on the medium and was identified as Kluyveromyces marxianus by observing its colony morphology and sequence analysis of the 26 S rDNA D1/D2 region. The fermentation conditions of ginseng for the transformation of ginsenoside Rg3 by Kluyveromyces marxianus were optimized using one-factor-at-a-time method and response surface methodology with a three-factor, three-level Box-Behnken design. A regression model was established with ginseng-to-water ratio（m/m）, inoculum concentration and fermentation time as independent variables. The results indicated that the optimized fermentation parameters were as follows： ginseng-to-water 1：2.65, inoculum concentration 2.94%, and fermentation time 3 days. Under these conditions, the content of Rg3 was 3.31 mg/g and its transformation rate was 248%. In conclusion, the results of this study can provide theoretical data for industrial production of fermented ginseng.