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Stable and Efficient Biosynthesis of 5-Aminolevulinic Acid Using Plasmid-Free Escherichia coli
- Cui, Zhiyong, Jiang, Zhennan, Zhang, Jinhong, Zheng, Huihui, Jiang, Xin, Gong, Kai, Liang, Quanfeng, Wang, Qian, Qi, Qingsheng
- Journal of agricultural and food chemistry 2019 v.67 no.5 pp. 1478-1483
- Escherichia coli, aminolevulinic acid, biosynthesis, fermentation, genes, glucose, heme, medicine
- 5-Aminolevulinic acid (5-ALA) is a key metabolic intermediate of the heme biosynthesis pathway, which has broad application prospects in agriculture and medicine. However, segregational instability of plasmid-based expression systems and low yield have hampered large-scale manufacture of 5-ALA. In this study, two important genes of the 5-ALA C5 biosynthesis pathway, hemA and hemL, were integrated into Escherichia coli MG1655 for chemically induced chromosomal evolution (CIChE). The highest hemA and hemL copy-number, 98 per genome, was obtained in CIChE strain MG136. The 5-ALA titer of this strain reached 2724 mg/L in optimized condition. Then, after undergoing adaptative evolution and the deletion of recA, strain MG136a ΔrecA::FRT could stably produce 4550 mg/L 5-ALA from glucose, 450 times the amount produced by hemA-hemL single copy strain MG1655-hemAL. This study constructed a plasmid-free E. coli strain for 5-ALA production, which will provide the basis for further manipulation of metabolic regulation and optimization of fermentation.