产β-葡萄糖苷酶洋虫内共生真菌筛选、鉴定及联合转化人参皂苷作用机制

Screening and identification of two strains ofβ-glucosidase producing symbiotic fungi in Martianus dermestoides and the mechanism of combined transformation of ginsenoside

筛选、鉴定出洋虫成虫体内两株产β-葡萄糖苷酶真菌,两菌株联合发酵提高稀有皂苷转化率和发酵品质,对其动态发酵反应过程进行研究,明确人参皂苷的转化机制。通过MRS(七叶苷,柠檬酸铁)培养基筛选,18SrRNA基因扩增分别对两株产β-葡萄糖苷酶真菌进行鉴定,并与全组分人参皂苷发酵反应,利用LC-MS/MS对发酵产物进行分析。经鉴定两株产β-葡萄糖苷酶分别属于Chaetomium和Aspergillus属;WY1与人参主皂苷反应产物为Rd和Rh1;WY2与人参主皂苷反应产物为Rd、Rh1、Rg3和compound K;WY1/WY2双菌联合发酵有效提高了Rh1、Rg3和compound K的转化率,其转化途径为Re→Rg1→Rh1;Rf→Rh1;Rb1/Rb2/Rc→Rd→Rg3/compound K,人参二醇类皂苷比人参三醇类皂苷更容易被转化且大部分被转化为Rg3。

Two strains of fungi producingβ-glucosidase were screened and identified from Martianus dermestoides.The conversion of rare ginsenosides and fermentation quality were improved by combined fermentation of the two strains.The dynamic fermentation process was studied,and the mechanism of ginsenoside transformation was clarified.Screening was performed by MRS(aesculin,ferric citrate)medium.Two fungi producingβ-glucosidase were identified by 18 SrRNA gene amplification.The strains were fermented with total ginsenoside,the fermentation products were analyzed by LC-MS/MS.Two fungi producingβ-glucosidase were identified as genus Chaetomiumand Aspergillus respectively.The fermentation products of WY1 reacted with total ginsenosides were Rd and Rh1.The fermentation products of WY2 reacted with total ginsenosides were Rd,Rh1,Rg3 and compound K.The conversion rates of Rh1,Rg3 and compound K were improved by WY1/WY2 combined fermentation.The transformation path was Re→Rg1→Rh1;Rf→Rh1;Rb1/Rb2/Rc→Rd→Rg3/compound K.Protopanaxadiol-type ginsenosides were more easily converted than protopanaxatriol-type ginsenosides and most of the products are Rg3.