重组麦芽糖转葡萄糖基酶工程菌发酵条件的优化

对重组麦芽糖转葡萄糖基酶工程菌的发酵条件进行优化，通过单因素试验确定该菌株产麦芽糖转葡萄糖基酶的最佳发酵培养基为：糖蜜0.025g/mL、胰蛋白胨0.015g/mL、MgSO4 ·7H2O与K2HPO4的质量为7:1、FeSO4 ·7H2O 0.5g/L；以葡萄糖氧化酶法为指标测得最佳摇瓶发酵条件为：装液量100mL/250mL、转速200r/min、接种量5%、初始pH 7.0、最佳温度37℃、诱导阶段OD600nm=0.6、诱导温度30℃、诱导时间5h、诱导剂异丙基-β-D-硫代吡喃半乳糖苷(IPTG)浓度1mmol/L。经优化，重组麦芽糖转葡萄糖基酶的酶活力可达950U/mL，比初始条件下提高了近7倍。

Optimization of Fermentation Conditions for Genetically Engineered Recombinant Bacterium with Amylomaltase Gene

The optimal fermentation conditions for the genetically engineered recombinant bacterium with amylomaltase gene conserved in our laboratory were explored in this study. One-factor-at-a-time investigations showed that the optimal fermentation culture medium was composed of 0.025 g/mL molasses, 0.015 g/mL tryptone, MgSO4 ·7H2O/K2HPO4 ratio of 7:1, and 0.5 g/L FeSO4 ·7H2O. The optimal fermentation conditions determined based on gucose oxidase activity were 100 mL of medium in a 250 mL flask, shaking speed of 200 r/min, inoculum amount of 5%, initial pH of 7.0, fermentation temperature of 37 ℃, addition of the inducer IPTG at OD600nm ＝ 0.6, induction temperature of 30 ℃, induction period of 5 h and inducer concentration of 1 mmol/L. Under the optimal conditions, the amylomaltase activity was 950 U/mL, which was improved by 7 times compared with non-optimization conditions.