5-Ketofructose(5-KF)has a similar sweet taste quality as D-fructose,and cannot be metabolized by humans,giving it a low caloric value.These properties illustrate 5-KF can become a potential candidate for a non-nutritive natural sweetener.In this study,the 5-KF producing strain was constructed via overexpression of membrane-bound fructose dehydrogenase gene from Gluconobacter japonicus in Gluconobacter oxydans.By screening different expression hosts,expression vectors and promoters,the engineered strain QT-10 which can efficiently synthesis 5-KF was obtained.The fed fermentation process was optimized in a 3 L fermenter.Finally,650 g/L D-fructose could be completely transformed in 82 h with continuous fructose-feeding strategy,and up to 608 g/L 5-KF was reached with the yield of 94.6％and the space-time yield of 7.41 g/(L·h).
维普
万方数据