Study On Ginsenosides Conversion Activity Of Endophytes Isolated From Platycodon Grandiflorum And Codonopsis Pilosula

Ginseng is a traditional Chinese medicinal material,the main bioactive component of ginseng is ginsenosides,minor ginsenosides are more pharmaceutically active,due to their smaller molecular weight,higher bioavailability,and better permeability across the cell membrane.However,minor ginsenosides are not present in most natural ginseng plants or very low content,the application has been limited.In recent years,the application of endophytes on biotransformation has also attracted people's attention.Due to the endophytes long term co-evolutionary with hosts,the endophytes can produce various extracellular enzymes to promote the accumulation and biosynthesis of metabolites.The objective of the study is to obtainthe endophytes have ginsenosides conversion activity from Platycodon grandiflorum and Codonopsis pilosula containing of triterpenoids ingredient.In this study,a total of 47 P-glucosidase-producing endophytes were screened out among the isolated 101 endophytes form Platycodon grandiflorum and Codonopsis pilosula,3 high efficient strains having significant conversion activity were picked out through ginsenoside monomers transformation experiments,were respectively named JG09,JG10 and D19.Combined with the morphological observation and molecular identification,identified high efficient strains,and then constructed phylogenetic trees according to the sequencing results.The experiment results showed that endophytic bacteria JG09 belonged to Luteibacter;endophytic bacteria JG10 belonged to Luteibacter rhizovicinus;endophytic bacteria D19 belonged to Dyella.In the ginseng root total saponin conversion experienments,ginseng root totalsaponin as the substrate,fermentation conditions were optimized.The best conditions of endophyte JG09:LL medium,pH 4.0,the maximum yield of minor ginsenosides C-K,Rhl and F2 was separately 16%,10%and 35%;the best conditions of endophyte JG10:water medium,pH 4.0,the maximum yield of minor ginsenosides C-K,Rhl and F2 was separately 10%,6%and 22%;the best conditions of endophyte D19:water medium,pH 5.0,the maximum yield of minor ginsenosides C-K,Rh1 and F2 was separately 17%,8%and 30%.In the major ginsenosides conversion experienments,combining TLC with HPLC analysis to explore the bioconversion pathways of ginsenosides by endophyte JG09,and investigate the source of minor ginsenosides.The results showed that:the minor ginsenoside C-K resulted form protopanaxadiol-type major saponins Rbl,Rb2,Rc and Rd by endophytes,and the minor ginsenoside Rh1 resulted form protopanaxatriol-type major saponin Rgl by endophytes.The conversion pathways of ginsenoside monomers by endophyte JG09 would be as follows:Rbl ?Rd?F2?C-K;Rb2?C-O?C-Y?C-K;Rc?C-Mcl?C-Mc?C-K;Rg1?Rh1.In the conversion experienment of ginsenoside Rb1 by endophytes,comparedthe conversion activity of endophyte JG09,JG10 and D19.The results were as follows:endophyte JG09 was the strongest considering the activity on the whole,the maximum production rate of minor ginsenosides F2 and C-K separately reached to 94.53%and 66.34%;as for endophyte JG10,the maximum production rate of minor ginsenosides F2 and C-K separately reached to 98.71%and 32.30%;as for endophyte D19,the maximum production rate of minor ginsenosides F2 and C-K separately reached to 82.85%and 55.99%.