The specific activity of a recombinant beta-glucosidase from Pyrococcus furiosus for protopanaxatriol (PPT)-type ginsenosides followed the order Rf > R-1 > Re > R-2 > Rg(2), which were converted to Rh-1, Rg(1), Rg(1), Rh-1, and Rh-1, respectively. No activity was observed with Rg(1) and Rh-1. Thus, P. furiosus beta-glucosidase hydrolyzed the outer glycoside at the C-6 position in PPT-type ginsenosides whereas the enzyme did not hydrolyze the inner glucoside at the C-6 position and the glucoside at the C-20 position. The activity for Rf was optimal at 95 A degrees C, pH 5.5, 5 mM ginsenoside, and 32 U enzyme l(-1). Under these conditions, P. furiosus beta-glucosidase completely converted from R-1 to Rg(1) after 10 h, with a productivity of 0.4 g l(-1) h(-1) and completely converted Rf to Rh-1 after 1.2 h, with a productivity of 2.74 g l(-1) h(-1).