Biosynthesis of genipin from gardenoside catalyzed by β-glucosidase in two-phase medium

Genipin is an important bio-crosslinking agent with multiple physiological activities. In this paper, the competitive inhibition for activity of β-glucosidase by genipin was demonstrated. The stabilities of β-glucosidase in different organic solvents were investigated. Stability of β-glucosidase was satisfactory in the octanol-water and hexanol-water medium. The partition coefficients for gardenoside in the octanol-water and hexanol-water system were 0.17 and 0.76, while those for genipin were 42.57 and 37.75 respectively. The process for preparation of genipin was carried out in water, octanol-water and hexanol-water respectively, while gardenoside concentration was 0.25 μmol·ml^-1. The obtained genipin yields were 89.17%, 93.96% and 90.16% respectively. Furthermore, the effect of gardenoside concentration on genipin yield was also investigated. While in the octanol-water system, conversion rate of genipin was as high as 91.9% at the gardenoside concentration of 2.0 μmol·ml^-1, an increase of 12.2% compared to that in water. Using the octanol-water medium was helpful for partially eliminating product inhibition, improving genipin yield and simplifying product recovery.