Screening And Identification Of Strain For Ginsenoside Rb₁ Transformation And Enzymatic Properties Analysis Of Glucosidase

Panax ginseng C.A.Mey is a kind of traditional Chinese medicine,it has many pharmaceutical activities such as nutritious,promoting blood cycle,prolonging life.Ginsenosides are major pharmaceutical components in ginseng,recently,regarding to how to increase ginsenosides contents become a hot point in aspects of traditional Chinese medicine modernization research.The biotransformation of ginsenosides is that modifying the glycosyl on the C3 and C20 position of Panaxadiol ginsenosides or the C6 and C20 position of Panaxatriol ginsenosides using microbes or relative enzymes.These methods could hydrolysis the glycosyl of major ginsenosides to produce minor ginsenosides.The biotransformation methods have a advantage of lowcost,fewer by-products and extensive application.This paper firstly isolated a fungus Aspergillus sp.LFJ1403,which could convert ginsenoside Rb1 into Rd as the sole product,from ginseng plant soil.18 S rDNA and phylogenetic tree analysis indicated that Aspergillus sp.LFJ1403 was Aspergillus versicolor.Through comparing the conversion rates of differernt biotransformation systems,LFJ1403 was found to secrete abundant ginsenoside-converting enzymes out in spore production phase of plate culture.The spore suspension,which contain these exocrine enzymes,was easy to prepare and efficient for biotransformation of ginsenoside Rb1 to Rd.Under these optimum conditions: total ginsenosides concentration 1.25 mg/m L;converting temperature 37?;pH 5.0;biotransformation period 48 hours,the maximum yield of ginsenoside Rd was 1.20 mg/mL with a converting rate 96%(w/w).The ginsenoside Rb1 converting enzyme was separated by Q-Sepharose column and the substrate Rb1 converting test.This enzyme had a strong ability of ?-glucosidase activity and ginsenoside Rb1 hydrolysis.SDS-PAGE assay indicated that the molecular weight of ?-glucosidase was 97 KDa.In order to obtaining the optimal plant material ginseng hairy root,on the basis of screening a fungus Aspergillus versicolor,we tried to inducing the ginseng hairy root.Agrobacterium rhizogenes A4 and gentic engineering bacteria LBA4404-rolBC were used to infect the different explants of ginseng,the hairy roots of ginseng were induced successfully from the young root and were subject to enlarge cultivation as the source of substrate of ginsenoside-converting strain.