Optimizations of fermentation production of starch branching enzyme in recombinant Escherichia coli

Starch branching enzyme can increase the α- 1, 6- glycosidic bond to improve the physicochemical properties and functions of starch.In this paper, the recombinant Escherichia coli BL21 ( DE3) ( pET-20b ( +) /be) was used to produce intracellularly starch branching enzyme from Geobacillus thermoglucosidans. Firstly, the ultrasound conditions for extracting the recombinant enzyme were optimized.The results showed that the optimized conditions were as follows: the ultrasonic power output of 325 W, total working time of 15 min and OD600 of 1.4. In addition, the shaking flask fermentation conditions for the production of the recombinant enzyme was optimized achieving highest activity 222.4U /mL, and the optimized conditions were as follows: TB medium, pH7.0, induced by0.01 mmol /L IPTG at 25℃ for 12 h.