Biotransformation of Major Ginsenoside Rb to Rd by YAE-1 from Mongolian Fermented Milk (Airag).

YAE-1 strain separated from "airag" (Mongolian fermented mare's milk) produces β-glucosidase, which can convert ginsenoside Rb from Panax ginseng. Ginseng-derived bioactive components such as ginsenoside Rb have various immunological and anticancer activities. Airag was collected from five different mare milk farms located near Ulaanbaatar, Mongolia. YAE-1 strains were isolated from airag to examine the hydrolytic activities of β-glucosidase on Korean using an API ZYM kit. Supernatants of selected cultures having β-glucosidase activity were examined for hydrolysis of the major ginsenoside Rb at 40°C, pH 5.0. The YAE-1 strain was found to be nearly identical at 99.9% homology with DB-7B, and was thus named YAE-1. This strain exerted higher β-glucosidase activity than other enzymes. Reaction mixtures from YAE-1 showed great capacity for converting ginsenoside Rb to ginsenoside Rd. The β-glucosidase produced by YAE-1 was able to hydrolyze ginsenoside Rb and convert it to Rd during fermentation of the ginseng. The amount of ginsenoside Rd was highly increased from 0 to 1.404 mg/ml in fermented 20% ginseng root at 7 days.