Discovery of enzymes to biotransform ginsenoside Rd into ginsenosides F2 and CK using metagenomics and genomic mining.

Ginsenosides are the main active components of ginseng, including many types and different contents. Among them, minor ginsenosides have better biological functions and pharmacological activities than those of the major ginsenosides. However, minor ginsenosides cannot be obtained in large quantities, but by means of enzymatic transformation technology, some major ginsenosides can be de-glycosylated at a specific position to generate minor ginsenosides. In this study, we report two glycosidase genes associated with the conversion of ginsenoside Rd to ginsenosides F or CK. SWMU-CK-1 was identified among the total genes extracted from the feces of plum deer by local Blast screening for putative ginsenoside conversion function, which could cause the conversion of ginsenoside Rd → F → CK. The other gene was found in the Bifidobacterium breve 689b SGAir 0764 chromosome genome, which might have the same function as the β-glucosidase gene testified by the gene matching, named SWMU-F2-2, and can achieve the Rd → F transformation. This study reports two genes that enable achieving the biotransformation of rare ginsenosides, while it provides a new insight and a promising approach to explore new genes and develop new functions of existing genes.