Cloning and Characterization of Ginsenoside-Hydrolyzing β-Glucosidase from Lactobacillus brevis That Transforms Ginsenosides Rb1 and F2 into Ginsenoside Rd and Compound K

Abstract

The ginsenoside-hydrolyzing β-glucosidase gene (<i>bgy</i>2) was cloned from <i>Lactobacillus brevis</i>. We expressed this gene in <i>Escherichia coli</i> BL21(DE3), isolated the resulting protein, and then utilized the enzyme for the biotransformation of ginsenosides. The <i>bgy</i>2 gene contains 2,223 bp, and encodes a protein of 741 amino acids that is a member of glycosyl hydrolase family 3. β-Glucosidase (Bgy2) cleaved the outer glucose moieties of ginsenosides at the C-20 position, and the inner glucose at the C-3 position. Under optimal conditions (pH 7.0, 30°C), we used 0.1 mg/ml Bgy2 in 20 mM sodium phosphate buffer (PBS) for enzymatic studies. In these conditions, 1.0 mg/ml ginsenoside Rb1 and ginsenoside F2 were converted into 0.59 mg/ml ginsenoside Rd and 0.72mg/ml compound K, with molar conversion productivities of 69% and 91%, respectively. In pharmaceutical and commercial industries, this recombinant Bgy2 would be suitable for producting ginsenoside Rd and compound K.