采用摇瓶对重组大肠杆菌Escherichia coli BL21(DE3)/ pET28b-FDH外源表达甲酸脱氢酶发酵条件进行优化。结果表明，当诱导温度22 ℃，诱导剂IPTG浓度0.1 mmol/L，诱导时间16 h条件下，可溶性目的蛋白表达量为52.12 mg/g，相对于优化前的40.12 mg/g，提高了29.91 %。在此基础上，在5 L发酵罐上对外源表达甲酸脱氢酶发酵条件进行优化。结果表明，当诱导温度22 ℃，诱导剂乳糖质量浓度8 g/L，诱导时间16 h条件下可溶性目的蛋白表达量为41.26 mg/g，相对于优化前的34.15 mg/g提高了20.82%。利用该条件下培养的菌体经破碎后获得甲酸脱氢酶粗酶液与适当比例的苏氨酸脱氨酶及亮氨酸脱氢酶粗酶液进行匹配，在底物L-苏氨酸质量浓度为180 g/L，辅底物甲酸铵120 g/L，NAD+ 0.1 g/L，在1 L反应体系中，恒温水浴35 ℃，搅拌转速500 r/mim条件下，反应9 h后，底物转化率达99%以上，时空产率17.2 g/(L·h)，e.e.值99.5%以上。

The fermentation conditions were optimized by using a shaking bottle for the recombinant Escherichia coli BL21(DE3)/ pET28b-FDH exogenous expressions of formate dehydrogenase. The results showed that the soluble protein expression could reach 52.12 mg/g after induction by 0.1 mmol/L IPTG at 22 ℃ for 16 h, which was increased by 29.91% compared with that before optimization (40.12 mg/g). On this basis, the fermentation conditions of exogenous formate dehydrogenase were further optimized in 5 L fermenter. The optimized soluble protein expression in 5 L fermenter reached 41.26 mg/g after induction by 8 g/L lactose at 22 ℃ for 16 h. It increased by 20.82% compared with that before the optimization (34.15 mg/g). The obtained crude formate dehydrogenase from this fermentation together with threonine deaminase and leucine dehydrogenase were used as biocatalysts. Under the conditions of stirring speed 500 rpm, 35℃, 180 g/L L-threonine concentration, 120 g/L substrate ammonium formate, 0.1 g/L NAD+ in 1 L reaction system, after 9 h reaction, the substrate conversion rate was more than 99%, space-time yield was 17.2 g/(L·h), and e.e. value was more than 99.5%.