Characterization of sp. MBT213 Isolated from Raw Milk and Its Ability to Convert Ginsenoside Rb into Ginsenoside Rd from .

This study was conducted to isolate and characterize sp. MBT213 possessing β-glucosidase activity from raw milk, and examine the enzymatic capacity on the hydrolysis of a major ginsenoside (Rb). Strain MBT213 was found to have a high hydrolytic ability on ginsenoside Rb by Esculin Iron Agar test. 16S rDNA analysis revealed that MBT213 was sp. Crude enzyme of MBT213 strain exhibited high conversion capacity on ginsenoside Rb1 into ginsenoside Rd proven by TLC and HPLC analyses. The API ZYM kit confirmed that sp. MBT213 exerted higher β-glucosidase and β-galactosidase activity than other strains. Optimum pH and temperature for crude enzyme were found at 7.0 and 35°C in hydrolysis of ginsenoside Rb. After 10 d of optimal reaction conditions for the crude enzyme, ginsenoside Rb fully converted to ginsenoside Rd. Ginseng roots (20%) were fermented for 14 d, and analyzed by HPLC showed that amount of ginsenoside Rb1 significantly decreased, while that of ginsenoside Rd was significantly increased. The study confirmed that the β-glucosidase produced by sp. MBT213 can hydrolyze the major ginsenoside Rb1 and convert to Rd during fermentation of the ginseng. The β-glucosidase activity of this novel sp. MBT213 strain may be utilized in development of variety of health foods, dairy foods and pharmaceutical products.