Bacterial endophytes from ginseng and their biotechnological application

Abstract

Ginseng has been well-known as a medicinal plant for thousands of years. Bacterial endophytes ubiquitously colonize the inside tissues of ginseng without any disease symptoms. The identification of bacterial endophytes is conducted through either the internal transcribed spacer region combined with ribosomal sequences or metagenomics. Bacterial endophyte communities differ in their diversity and composition profile, depending on the geographical location, cultivation condition, and tissue, age, and species of ginseng. Bacterial endophytes have a significant effect on the growth of ginseng through indole-3-acetic acid (IAA) and siderophore production, phosphate solubilization, and nitrogen fixation. Moreover, bacterial endophytes can protect ginseng by acting as biocontrol agents. Interestingly, bacterial endophytes isolated from Panax species have the potential to produce ginsenosides and bioactive metabolites, which can be used in the production of food and medicine. The ability of bacterial endophytes to transform major ginsenosides into minor ginsenosides using β-glucosidase is gaining increasing attention as a promising biotechnology. Recently, metabolic engineering has accelerated the possibilities for potential applications of bacterial endophytes in producing beneficial secondary metabolites.

Keywords: Bacterial endophytes; Biotransformation; Ginseng; Ginseng pathogens; Ginsenosides.

Graphical abstract

Fig. 1

Chemical structures and biological activities of ginsenoside derivatives. Glc, β-D-glucopyranosyl; GlcUA, β-D-gulcuronic acid.

Fig. 2

Biotransformation pathway of ginsenoside Rb1 by bacterial and fungal endophytes isolated from Panax ginseng.

Fig. 3

Diversity and plant growth-promoting activity of bacterial endophytes from ginseng.