title: Microbial conversion of major ginsenosides in ginseng total saponins byPlatycodon grandiflorumendophytes.
abstract: BACKGROUND
  In this study, we screened and identified an endophyte JG09 having strong biocatalytic activity for ginsenosides fromPlatycodon grandiflorum, converted ginseng total saponins and ginsenoside monomers, determined the source of minor ginsenosides and the transformation pathways, and calculated the maximum production of minor ginsenosides for the conversion of ginsenoside Rb1 to assess the transformation activity of endophyte JG09.
  
  
  METHODS
  The transformation of ginseng total saponins and ginsenoside monomers Rb1, Rb2, Rc, Rd, Rg1 into minor ginsenosides F2, C-K and Rh1 using endophyte JG09 isolated by an organizational separation method and Esculin-R2A agar assay, as well as the identification of transformed products via TLC and HPLC, were evaluated. Endophyte JG09 was identified through DNA sequencing and phylogenetic analysis.
  
  
  RESULTS
  A total of 32 β-glucosidase-producing endophytes were screened out among the isolated 69 endophytes fromP. grandiflorum. An endophyte bacteria JG09 identified asLuteibacter sp. effectively converted protopanaxadiol-type ginsenosides Rb1, Rb2, Rc, Rd into minor ginsenosides F2 and C-K, and converted protopanaxatriol-type ginsenoside Rg1 into minor ginsenoside Rh1. The transformation pathways of major ginsenosides by endophyte JG09 were as follows: Rb1→Rd→F2→C-K; Rb2→C-O→C-Y→C-K; Rc→C-Mc1→C-Mc→C-K; Rg1→Rh1. The maximum production rate of ginsenosides F2 and C-K reached 94.53% and 66.34%, respectively.
  
  
  CONCLUSIONS
  This is the first report about conversion of major ginsenosides into minor ginsenosides by fermentation withP. grandiflorumendophytes. The results of the study indicate endophyte JG09 would be a potential microbial source for obtaining minor ginsenosides.
authors.affiliation: Key Laboratory of Natural Resources of Changbai Mountain and Functional Molecules, Ministry of Education, Yanbian University, Yanji, China.
authors.forename: Lei
authors.initials: L
authors.lastname: Cui
authors.affiliation: Key Laboratory of Natural Resources of Changbai Mountain and Functional Molecules, Ministry of Education, Yanbian University, Yanji, China.
authors.forename: Song-Quan
authors.initials: SQ
authors.lastname: Wu
authors.affiliation: College of Resources and Environmental, Jilin Agricultural University, Changchun, China.
authors.forename: Cheng-Ai
authors.initials: CA
authors.lastname: Zhao
authors.affiliation: Key Laboratory of Natural Resources of Changbai Mountain and Functional Molecules, Ministry of Education, Yanbian University, Yanji, China.
authors.forename: Cheng-Ri
authors.initials: CR
authors.lastname: Yin
keywords: Platycodon grandiflorum; conversion; endophytes; minor ginsenosides