Production of steviol from steviol glucosides using β-glucosidase from a commercial pectinase, Sumizyme PX

Objective: To purify and characterize a specific enzyme from a commercial pectinase for the production of steviol from stevioside (Ste) without adding organic solvent and to improve steviol production. Results: Commercial Sumizyme PX converted Ste to steviol with a yield of 98%. β-Glucosidase from Sumizyme PX (βglyPX) was purified in three steps with 12.5-fold purification and 51% yield. The specific activity of the purified βglyPX was 141 U/mg. The molecular weight of βglyPX was ~ 116 kDa on SDS-PAGE. Its optimum activity was at pH 3.5 and 65 °C. It was stable for 12 h up to 55 °C and for 24 h at pH 2–9.5. K_m values of βglyPX for pNPGal, oNPGlc, lactose, and Ste were 2.4, 0.7, 18, and 7.8 mM, respectively. The optimum conditions for steviol production were 55 °C, 900 U/ml, 80 mg Ste/ml, 12 h. Conclusion: βglyPX contains great potential for industrial steviol production from Ste.