海藻酸钠包埋的酵母菌转化人参皂苷Rb_1的研究

Study on biotransformation of ginsenoside Rb_1 by immobilized yeast embedded in sodium alginate

为探索海藻酸钠包埋酵母菌转化人参皂苷Rb1的最佳条件,选用浓度为1.25×108个·mL-1的酵母菌菌悬液进行包埋,使用紫外分光光度计测定发酵液中人参皂苷Rb1含量变化计算生物转化率。通过单因素和正交设计试验分别考察海藻酸钠浓度、包埋时间、接种量和CaCl2浓度对所包埋的酵母菌转化人参皂苷的影响,最终获得了海藻酸钠包埋酵母菌转化人参皂苷Rb1的最佳条件为包埋时间45min,接种量7%,海藻酸钠浓度5%,CaCl2浓度10%。在该条件下,所包埋酵母菌对人参皂苷Rb1的最高生物转化率为31.51%,较以往未包埋的酵母菌转化人参皂苷Rb1的生物转化率提高约3%～5%。本研究首次利用海藻酸钠包埋酵母菌转化人参皂苷Rb1,解决了酵母菌种子不能重复使用等问题,简化了灭菌、菌种活化等步骤,为人参皂苷Rb1等苷类物质的高效生物转化提供了很好的思路和可借鉴的成功范例。

In order to explore the optimal condition by using the sodium alginate to embed the yeast and further using immobilized yeast to biotransform ginsenoside Rb1,1.25 ×10^8 numbers per milliter concentration thalli suspent of yeast was selected to immobilize,the change of ginsenoside content in ferment liquid was measured by the ultraviolet spectrophotometer method and was calculated to be biotransformation efficiency.The influenced factors of sodium alginate concentration,embedded time,inoculum and calcium chloride concentration on biotransformation efficiency of ginsenoside Rb1 with immobilized yeast were respectively investigated by single factor experiment and orthogonal experiment.The results showed that the optimal immobilized condition was as below：5% sodium alginate solution,45 min embedded time,7% inoculum and 10% calcium chloride solution.Under this condition,the highest biotransformation efficiency of 31.51% was obtained,which was 3%-5% higher than that of using the free yeast.In this study,immobilized yeast embedded in sodium alginate was for the first time used for the biosynthesis of ginsenoside Rb1,which would not only ignore the more times of preparing yeast seed and but also simplify procedures of multifarious sterile and strain activation,and therefore,the provided a good idea and a successful example for highly efficient biotransformation of ginsenoside-like bioactive substances.