Bioconversion of Ginsenoside Rb1 to the Pharmaceutical Ginsenoside Compound K using Aspergillus usamii KCTC 6954

β-Glucosidase from Aspergillus usamii KCTC 6954 was used to convert ginsenoside Rb1 to compound K, which has a high bio-functional activity. The enzymatic activities during culturing for 15 days were determined using ρ-nitrophenyl-β-glucopyranoside. The growth rate of the strain and the enzymatic activity were maximized after 6 days (IU; 175.93 μM ml-1 min-1). The activities were maximized at 60oC in pH 6.0. During culturing, Rb1 was converted to Rd after 9 d and then finally converted to compound K at 15 d. In the enzymatic reaction, Rb1 was converted to the ginsenoside Rd within 1 h of reaction time and compound K could be detected after 8 h. As a result, this study demonstrates that Rb1→Rd→F2→compound K is the main metabolic pathway catalyzed by β-glucosidase and that β-glucosidase is a feasible option for the development of specific bioconversion processes to obtain minor ginsenosides such as Rd and compound K. KCI Citation Count: 5