增强组成型重组大肠杆菌质粒稳定性的发酵策略

Fermentation Strategy for Enhancing Plasmid Stability of Constitutive Recombinant Escherichia coli

质粒稳定性是影响基因工程菌外源蛋白表达的重要因素,同时,外源蛋白的表达又影响着质粒稳定性。与诱导型表达系统相比,在组成型表达系统中,由于外源蛋白的持续表达,导致细胞代谢负担加重,质粒稳定性的控制更加困难。通过对组成型大肠杆菌DH5α/pKKFPGA发酵过程的优化,增强了质粒稳定性,发酵结束时,仍然维持在85%左右,表达产物粪产碱杆菌青霉素酰化酶的酶活单位达到23 384 U.L-1。

Plasmid stability is one of the most important factors, which influences the production of heterologous proteins significantly, and in reverse, heterologous proteins＇expression can also have an influence on plasmid stability. Since constitutive expression system is more likely leading to the loss of plasmid compared with inducible system, enhancing the plasmid stability of a constitutive, system is more difficult. By the optimization of fermentation process, the plasmid stability of constitutive DH5α/pKKFPGA is highly enhanced, maintaining about 85 % at the end of fermentation, and the enzyme activity of Alcaligenes faecalis penicillin G amidase（AfPGA） reaches to 23 384 U · L^-1.