Dekkera bruxellensis, a beer yeast that specifically bioconverts mogroside extracts into the intense natural sweetener siamenoside I

In response to growing concerns about the consumption of artificial sweeteners, the demand for natural sweeteners has recently increased. Mogroside V is a common natural sweetener extracted from the fruit of Siraitia grosvenorii, but its taste should be improved for marketability. Here, we screened various microbes for the ability to perform selective hydrolysis of glycosidic bonds in mogroside V, converting it to siamenoside I, which has a higher sweetening power and better taste than other mogrosides. Dekkera bruxellensis showed the most promising results in the screen, and the Exg1 gene (coding for a β-glucosidase) of D. bruxellensis was cloned and purified. We then used HPLC-MS/MS to assess the β-glucosidase activity of purified enzymes on p-nitrophenyl β-glucoside and mogroside V. The results demonstrated that D. bruxellensis had a unique enzyme that can selectively hydrolyze mogrol glycosides and promote the conversion of the natural sweetener mogroside V to siamenoside I.