P92: Identification and Characterization of Mucilaginibacter sp. QM49 β-Glucosidase and Its Application for Production of Pharmaceutically Active Minor Ginsenoside Rh1(S) and Rg2(S)

To produce pharmacological active rare ginsenosides Rg₂(S) and Rh₁(S) using crude ginseng extracts, an efficient ginsenosides-transforming β-glucosidase (BglQM) was cloned from Mucilaginibacter sp. QM49 which was isolated from the soil of a ginseng farm as having activity for biotransformation of various major ginsenosides. The bglQM consisted of 2346 bp (781 amino acid residues) with a predicted molecular mass of 85.6 kDa. Sequence analysis of BglQM revealed that it was classified in glycoside hydrolase family 3. The recombinant BglQM showed optimum activity to at 30°C and pH 8.0.  The enzyme catalyzed the transformation of major ginsenosides Rb₁, Rd, Rc, Rb₂, Re and Rg₁ into the more pharmacologically active rare ginsenosides. Among them, BglQM can efficiently transform the protopanaxatriol(PPT) type ginsenosides Re and Rg₁ into Rg₂(S) and Rh₁(S) by hydrolyzing the attached glucose moiety at the C6 and C20 positions, respectively. The Km of Re and Rg₁ were 0.69 ± 0.06 mM and 0.45 ± 0.02 mM, respectively, and the Vmax values of 16.13 ± 0.29 μmol min⁻¹ mg⁻¹ of protein and 51.56 ± 1.35 μmol min⁻¹ mg⁻¹ of protein. Application of BglQM was performed with crude protopanaxatriol type ginsenoside extracts (PTGE) to produce pharmacological Rg₂(S) and Rh₁(S). Then, gram-scale pure ginsenoside Rg₂(S) and Rh₁(S) were purified using a silica resin. To best our knowledge, our work is the first example of gram-scale productions of pharmacologically active Rg₂(S) and Rh₁(S) from PTGE using recombinant enzyme.