Production of aglycon protopanaxadiol via compound K by a thermostable β-glycosidase from Pyrococcus furiosus

The production of compound K and aglycon protopanaxadiol (APPD) from ginsenoside Rd and ginseng root extract was performed using a recombinant β-glycosidase from Pyrococcus furiosus. The activity for Rd was optimal at pH 5.5 and 95°C with a half-life of 68 h at 95°C. β-Glycosidase converted Rb1, Rb2, Rc, and Rd to APPD via compound K. With increases in the enzyme activity, the productivities of compound K and APPD increased. The substrate concentration was optimal at 4.0 mM Rd or 10% (w/v) ginseng root extract; 4 mM of Rd was converted to 3.3 mM compound K with a yield of 82.5% (mol/mol) and a productivity of 2,010 mg l−1 h−1 at 1 h and was hydrolyzed completely to APPD with 364 mg l−1 h−1 after 5 h. Rb1, Rb2, Rc, and Rd at 3.9 mM in 10% ginseng root extract were converted to 3.1 mM compound K with 79.5% and 1,610 mg l−1 h−1 at 1.2 h and were hydrolyzed completely to APPD with 300 mg l−1 h−1 after 6 h. The concentrations and productivities of compound K and APPD in the present study are the highest ever reported.