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研究了不同碳源(葡萄糖、乳酸和乙酸)以及IPTG诱导对工程菌MM2表达霍乱毒素B亚单位(CTB)的影响,ctb基因位于lac启动子的下游。在YC培养基中分别加入0.048mol/L的葡萄糖、0.102mol/L的乳酸和0.167mol/L的乙酸,它们在完全氧化后可产生相同的能量。结果表明,加入葡萄糖会大幅度降低ctb基因的表达水平,其原因和培养过程中pH值下降有关;加入乳酸可提高ctb基因表达水平1.15倍,且不抑制菌体生长;加入乙酸可提高ctb基因的表达水平0.9倍,但对菌体生长有抑制作用。不同时间及不同浓度的IPTG诱导未能提高ctb基因的表达水平,说明lac启动子对ctb基因的表达没有影响或影响很小。
The effects of different carbon sources (glucose, lactate and acetate) and IPTG induction on cholera toxin B subunit (CTB) expression in engineered bacteria MM2 were studied. The ctb gene was located downstream of the lac promoter. 0.048 mol / L glucose, 0.102 mol / L lactic acid and 0.167 mol / L acetic acid, respectively, were added to YC medium, and they all produced the same energy after complete oxidation. The results showed that adding glucose significantly reduced the expression level of ctb gene. The reason was related to the decrease of pH value during culture. The addition of lactate increased the ctb gene expression by 1.15 times and did not inhibit the growth of the cells. Acetic acid increased the ctb gene 0.9 times the expression level, but the inhibition of cell growth. Induction of IPTG at different times and concentrations did not improve the expression level of ctb gene, indicating that lac promoter had no or little effect on ctb gene expression.