酵母菌对高含量人参皂苷的转化及其分子鉴定

Bioconversion of major ginsenosides by two yeast strains and their molecular identification

人参皂苷尤其是稀有人参皂苷具有重要的药理活性,但在人参中含量极其稀少。本研究运用高效液相色谱技术,对两株酵母发酵液的粗酶提取物转化高含量人参皂苷Rb1和Rc生成稀有皂苷Rd和Rg3进行了分析,并通过对酵母菌株18S rDNA的克隆和序列分析对以上菌种进行了初步分类鉴定。结果显示,两株酵母菌均可产生水解Rb1生成Rd及其他产物的人参皂苷糖苷酶,也均可产生水解Rc形成Rg3及其他产物的人参皂苷糖苷酶;Rc转化形成Rg3并非Rc转化的主要途径;两株酵母菌株在分类地位上均属于酵母菌属。

The pharmaceutical activities of minor ginsenosides are found to be superior to those of the major ones, but they are present in ginseng only in small percentages. In this study, the crude enzymes extracted from two yeast strains were used to hydrolyze the major ginsenosides Rb1 and Rc, and the contents of Rb1 and Rc and their metabolites were analyzed by high performance liquid chromatogrphy. 18S rDNA sequences of the yeast strains were cloned and analyzed. Two yeast strains both produced ginsenoside glycosidases which could convert ginsenosides Rb1 to Rd and Rc to Rg3 . The conversion of Rc to Rg3 was not the major way to hydrolyze Rc. The phylogenetic tree based on the 18S rDNA sequences of the two yeast strains and other ten yeast species which belong to different genera retrieved from GenBank revealed that the 18S rDNA sequences of the two yeast strains were highly homologous to that of Saccharomyces cerevisiae. They belong to Saccharomyces genus.