研究生物合成硫模块对L-甲硫氨酸产量的影响并优化了发酵条件。利用实验室构建的重组菌株,用trc启动子替换基因组上cysK的组成型启动子,在质粒pA*H上插入glpE和nrdH基因;通过构建PG3启动子文库,获得转录强度最高的p32启动子,进一步优化硫模块,最后通过对培养基的优化提高了硫代硫酸盐的供给,从而提高L-甲硫氨酸产量。结果表明：使用构建得到的E. coli W3110 JAHFEBL trc-cysK/pA*H-p32-nrdH-glpE菌株,发酵48 h后L-甲硫氨酸摇瓶水平产量达到1.3 g/L,较对照组提升了41.5%;通过对培养基的进一步优化,L-甲硫氨酸产量最终达到2.3 g/L,相比未优化的发酵水平提高了77.0%,且该研究为其他含硫氨基酸的生物合成提供了基础。
This study was conducted to increase the titer of L-methionine. The effects of sulfur module on L-methionine production were investigated, and the fermentation condition was optimized. The native promoter of cysK was replaced with trc promoter on the genome, and glpE and nrdH were co-expressed on plasmid pA*H. In order to further study the effects of strong promoter on L-methionine synthesis, the p32 promoter was obtained from the PG3 promoter library. The fermentation media was optimized to improve the supply of thiosulfate to increase the yield of L-methionine. After 48 h fermentation of the strain Escherichia coli W3110 JAHFEBL trc-cysK/pA*H-p32-nrdH-glpE, the titer of L-methionine was 1.3 g/L, which increased by 41.5% in comparison to that of the control. Using optimized medium, the titer of L-methionine reached 2.3 g/L, which was 77.0% higher than that before optimization. Therefore, this paper provides a basis for biosynthesising other sulfur-containing amino acids.
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