Cloning, expression and characteristic of glycosyl-transferase UGT76G1 from Stevia rebaudiana

Objective:Stevioside which was high in content but has a strong bitter sweet in Steviosides is specifically catalyzed to generate Rebaudioside A high in sweetness by the use of glycosyl transferase UGT76G1.Methods:The synthetic glycosyl-transferase UGT76G1 coding gene after modified was inserted into the vector pYES2 with the restriction site of EcoR I and Xho I in order to construct the recombinant plasmid pYES2-UGT which was then imported to Saccharomyces cerevisiae YPH499.The recombinant strain was induced to express by 2% galactose.Results:Determined the best induction start time was 12h.The nature of this restructuring enzyme was investigated and the optimal conditions were investigated as following:the pH of phosphate salt solution was 8.0, the reaction temperature was 40℃, the reaction time was 36h.Condusion:This study laid a foundation for building an economic and efficient biological catalysis method to modify the taste of Stevioside.