rhtB基因过表达苏氨酸工程菌发酵过程的优化控制

目的]构建了负责运输苏氨酸至胞外的转运蛋白的关键基因rhtB过表达的苏氨酸发酵菌M122,考察不同的碳源、氮源及pH对该重组菌产L-苏氨酸的影响。方法]选用不同的碳、氮源对L-苏氨酸生产菌株的发酵过程进行分析,对发酵培养基的碳、氮源及pH进行优化。结果]定向改造后苏氨酸发酵菌对营养物质的利用效率增加,使用蔗糖作为碳源发酵时,摇床培养L-苏氨酸产量为28.1 g/L;以（NH4）2SO4或酵母粉作为氮源发酵时,L-苏氨酸产量分别为27.8和28.2 g/L,均优于使用其他氮源时苏氨酸的产量。对发酵的最适pH研究表明,中性条件下更有利于菌体的生长和L-苏氨酸的产生。结论]确定了苏氨酸发酵菌M122的最佳碳源为蔗糖,最佳氮源为（NH4）2SO4或酵母粉,最适pH为7.0。

Optimization of Culture Conditions of rhtB Gene Overexpressed Threonine-producing Strain

Objective] The aim was to construct key gene rhtB overexpressed threonine-producing E.coli strains which transported threonine to extracellular translocator,and to investigate the effect of different carbon and nitrogen sources and pH value on L-threonine.Method] The fermentation process of different carbon and nitrogen sources on L-threonine yield strains were analyzed to optimize carbon and nitrogen sources of fermentation medium and pH.Result] Data showed that the suitable carbon source for threonine production by E.coli M122 was sucrose whose yield of threonine was 28.1 g/L.When ammonium sulfate or yeast extract were acted as nitrogen sources,production reached 27.8 and 28.2 g/L,respectively.The yield of threonine was pH dependent and occurred at approximately pH 7.0.Conclusion] The best carbon source for threonine production by E.coli M122 was sucrose.Either of sources including ammonium sulfate or yeast extract could be used as optimal nitrogen.pH is a critical factor in threonine production,which should be set at 7.0.