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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.