Ginsenoside Rb-1 is the most predominant ginsenoside in Panax species (ginseng) and the hydrolysis of this ginsenoside produces pharmaceutically active compounds. Caulobacter leidyia GP45, one of the isolates having strong beta-glucosidase-producing activity, converted ginsenoside Rb-1 to the active metabolites by 91%. The structures of the resultant metabolites were identified by NMR. Ginsenoside Rb-1 had been consecutively converted to ginsenoside Rd (1), F-2 (2) and compound K (3) via the hydrolyses of20-C beta-(1 -> 6)-glucoside, 3-C beta-(1 -> 2)-glucoside, and 3-C beta-glucose of ginsenoside Rb-1.