Ginsenosides are known as the main active components in ginseng and minor ginsenosides are more pharmaceutically active than major ginsenosides.Ginsenoside compound K especially exhibits anti-genotoxic activity and anti-allergic activity against tumor invasion and metastasis.So it is essential that produced the higher pharmacologically active minor ginsenoside compound K.In the study,aβ-glucosidase gene(bgy1)from Lactobacillus brevis was cloned and expressed in Escherichia coli.Recombinant β-glucosidase(Bgy1)was purified,and its molecular weight was approximately 87.5 kDa,as determined by SDS-PAGE.The Bgy1 had high selectivity for cleaving the outer glucose at the C-20 position and the innerglucose at the C-3 position in protopanaxadiol-type ginsenosides.The Bgy1 optimal activity was at pH 6.0 and 30℃,and stability significantly decreased above 50℃.The Bgy1 did not require Na+,K+,Mn2+,Fe3+,Ca2+,and Mg2+ for activity;The hydrolytic activity for the pNP and oNP substrates was as follows: oNP-β-D-glucopyranoside >pNP-β-D-glucopyraoside.Using 0.1 mg mL-1 enzyme in 20 mM sodium phosphate buffer at 30℃ and pH 6.0,ginsenoside F2 was transformed into compound K within 1 h and gypenoside(ⅩⅦ)was transformed into compound K within 6 h.The Bgyl hydrolyzed ginsenoside F2 and gypenoside(ⅩⅦ)along the following pathway: F2 → compound K,gypenoside(ⅩⅦ)→ gypenoside LXXV → compound K.