Enzymatic Synthesis of Sucrose-6-acetate by a Novel Immobilized Fructosyltransferase From Aspergillus sp. GX-0010

BACKGROUND: Sucralose is an ideal food sweetener and sucrose-6-acetate (s-6-a) is a key intermediate for synthesis of sucralose. Synthesis of s-6-a was studied by free fructosyltransferase (FTase) from Aspergillus oryzae. Because of the limitations of free enzyme in stability and reusability, a FTase obtained from the new isolated Aspergillus sp. GX-0010 was immobilized and investigated for the potential of s-6-a synthesis. OBJECTIVES: The synthesis of s-6-a with sucrose and glucose-6-acetate (g-6-a) by immobilized fructosyltransferase (IFTase) from a novel Aspergillus sp. GX-0010 was studied, and its synthesis conditions were also optimized. MATERIALS AND METHODS: Aspergillus sp. GX-0010 was isolated. The effects of reaction time, ratio of g-6-a to sucrose, pH, substrate (sucrose and g-6-a) concentrations, IFTase concentration and temperature on the synthesis of s-6-a were investigated. RESULTS: IFTase was able to catalyze sucrose and g-6-a to synthesize the s-6-a. Thermal and pH stability of IFTase were promoted once compared to the FTase. The optimal condition for IFTase catalysis was obtained at 50 °C, 60 min reaction time, pH 6.5, 1:2 ratio of g-6-a to sucrose and 35.0 g.L(-1) concentration of enzyme. Under this optimal condition, a g-6-a conversion rate of 24.96% was reached. CONCLUSIONS: This study showed IFTase has a great potential in the biosynthesis of s-6-a, a key intermediate of sucralose synthesis.