流加培养方式对大肠杆菌XD-12发酵的影响研究

Study on the Effects of Fed-batch Culture Method of Escherichia coli XD-12 Fermentation

[目的]研究大肠杆菌流加培养方式,提高转氨酶供体——大肠杆菌XD-12的发酵浓度。[方法]通过研究碳源流加、氮源流加、pH控制流加对发酵的影响,获得了优化的培养条件。[结果]产转氨酶大肠杆菌的最佳培养条件为:温度37℃,搅拌转速500 r/m in,通气量1.5 L/m in,培养基初始pH为7.0,控制发酵过程pH为7.5,初始葡萄糖浓度5 g/L,初始氮源为5 g/L蛋白胨+1.5 g/L牛肉膏,从葡萄糖浓度下降为2 g/L开始每隔2 h间歇流加120 g/L的糖,从8 h起每隔2 h间歇流加15 g/L蛋白胨+4.5 g/L牛肉膏。在此条件下培养24 h,大肠杆菌的菌体干重浓度达9.66 g/L,较分批培养提高了104.7%。[结论]这对降低酶法制备L-苯丙氨酸的生产成本、提高生产效率、满足日益增长的市场需求具有重要的现实意义。

[Objective] The research aimed to study the fed-batch culture method of Escherichia coli and enhance the fermentation concentration of transaminase donor,E.coli XD-12.[Method] The effects of carbon source feeding,nitrogen source feeding,feeding with pH control on E.coli fermentation were studied to obtain the optimal culture conditions.[Result] The optimal cultural conditions for transaminase-producing E.coli were as follows：temperature of 37 ℃,agitation speed of 400 r/min,aeration quantity of 1.5 L/min,initial pH of medium of 7.0,for controlling fermentation process pH of 7.5,initial glucose concentration of 5 g/L,initial nitrogen source of 5 g/L peptone ＋1.5 g/L beef extract,120 g/L glucose solution was intermittently fed at an interval of 2 h after glucose concentration declined to 2 g/L.And 15 g/L peptone and 4.5 g/L beef extract were intermittently fed at an interval of 2 h after 8 hours.After culture 24 h under these conditions,the cell dry weight concentration of E.coli reached 9.66 g/L,104.7% higher than that in batch culture.[Conclusion] This research was of an important realistic significance for reducing the production cost of preparing L-phenylalanine by enzyme method,enhancing the production efficiency of L-phenylalanine,sufficing the increasing market requirements of L-phenylalanine.