Optimal Controlling for Fermentation Process of Threonine-producing Strain Overexpressing rhtB Gene

rhtB基因过表达苏氨酸工程菌发酵过程的优化控制(英文)

[Objective] The aim was to construct threonine-producing strain M122 overexpressing key gene rhtB for transporter protein to transport threonine to the extracellular, and to investigate effects of different carbon or nitrogen sources and pH values on L-threonine production caused by the recombinant strain. [Method] The fermentation process of L-threonine-producing strain was analyzed by different carbon or nitrogen sources, and carbon or nitrogen sources and pH in fermentation medium were also optimized in this study. [Result] After direct modification, the uti- lization efficiency of threonine-producing strain on nutrients increases. When sucrose was used as carbon source for fermentation, Lothreonine yield via shaking culture was 28.1 g/L When （NH4）2SO4 or yeast powder was used as nitrogen source for fermenta- tion, L-threonine yield was 27.8 and 28.2 g/L respectively, which were all higher than that of other nitrogen sources. The study on optimal pH value showed that it was more beneficial for strain growth and L-threonine yield on neutral condition. [Conclusion] The best carbon source for threonine-produing strain M122 was sucrose, while the best nitrogen source was （NH4）2804 or yeast powder, and the most suit- able pH value was 7.0.

[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28.1g/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28.2g/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。