Study On Separation And Identification Of Probiotics And The Interactions With Ginsenoside Rb1

Ginsenosides are the main active bioactive components of ginseng.Recently,due to the potential application value of ginseng in cosmetics,beverages,nutritious foods and wine,ginseng functional foods have occupied a dominant position in the market.Compared with high-content major ginseng,rare ginsenosides have higher activity with the lowest content in nature.Therefore,the major productive methods of rare ginsenosides are micro-degradation,chemical hydrolysis and enzymatic methods.Chemical hydrolysis reaction requires higher reaction conditions and cost,while the biotransformation of microbial enzyme systems is safer and more efficient.However,most of the microbes strains are non-food grade.Therefore,it is necessary to find foodgrade microorganisms which could be converted to ginsenosides efficiently.As food-grade microbes,probiotics are mainly found in the intestinal tract.On the one hand,it could directly promote human body's absorption in nutrient,affecting metabolic diseases such as diabetes and obesity,and maintain intestinal mucosal barrier.On the other hand,it could release signal molecules that circulate with the blood and interact with other organs,helping to improve immunity and regulate neurological diseases.In addition,probiotics are also involved in the formation of brain-intestineaxis.In this study,we tried to screen out probiotic strains that could be biotransformed into ginsenosides efficiently.The main results are shown as following:The Isolation and Identification of Probiotics.In this study,we used the streaking plating method to separate the mixed bacteria in drugs.Then we designed specific primers based on 16 s rDNA Hypervariable Region Sequences of Lactobacillus salivarius strain JCM 1231,Lactobacillus fermentum strain NBRC 15885,Lactobacillus rhamnosus strain JCM 1136,Streptococcus thermophilus strain ATCC 19258,Enterococcus faecium strain DSM 20477 and Akkermansia muciniphila ATCC BAA-835.Specific PCR amplifications were used to indentify those isolated strains preliminarily.In order to avoid false positives results,we still needed to sequence their 16 s rDNA and build a phylogenetic tree to complete the whole work.In this research part,we did not only get seperate specific primers of five bacterial strains but also ioslate and identigy them.Study on Interaction Between Probiotics and Biotransformation of Ginsenosides.In this study,we selected six strains of probiotics.Firstly we fermented major ginsenoside Rb1 with these strains.Then ginsenosides were extracted from fermentation products by water-saturated butanol.A quantitative analytical method was established for ginsenoside Rb1,using reversed phase HPLC.We took this method to detect fermentation products.It is found that although there was a slight decrease in substrate concentration after fermentation,new chromatographic peaks did not appear,which means no new ginsenoside was produced by these six strains.Baesd on previous research of related literatures,we analyzed the preliminary experiment results.1)It is assumed that there will be slight differences in genes between different substrains under the same strain,which lead to huge differences in traits.These sub-strains do not produce the relevant enzymes for ginsenoside Rb1 and have no conversion ability;2)The medium used for fermentation(MRS medium),due to its high content of glucose,inhibits the expression and activity of related enzymes,which leads to failure of transformation.