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Modulating heterologous pathways and optimizing fermentation conditions for biosynthesis of kaempferol and astragalin from naringenin in Escherichia coli
- Pei, Jianjun, Chen, Anna, Dong, Ping, Shi, Xuejia, Zhao, Linguo, Cao, Fuliang, Tang, Feng
- Journal of industrial microbiology & biotechnology 2019 v.46 no.2 pp. 171-186
- Escherichia coli, Ginkgo biloba, batch fermentation, biochemical pathways, biosynthesis, gene dosage, genes, kaempferol, naringenin, screening, transferases
- Kaempferol and astragalin are used as standards to assess the quality of Ginkgo biloba extract and Radix astragali, respectively, and possess numerous biological properties. In this study, we constructed a recombinant strain with a highly efficient biosynthetic pathway of kaempferol by screening key enzyme genes, designing a synthetic fusion enzyme and increasing the gene copy number. By optimizing conversion and fed-batch fermentation conditions, maximal kaempferol production reached 1184.2 ± 16.5 mg/L, which represents the highest yield of kaempferol from naringenin reported to date. Based on this result, glycosyltransferase (AtUGT78D2) and an efficient UDP-glucose synthesis pathway were introduced into the recombinant strain to produce astragalin, resulting in maximal astragalin production at 1738.5 ± 24.8 mg/L without kaempferol accumulation. The efficient synthesis pathway described in this study for kaempferol and astragalin biosynthesis can be widely used for flavonoid biosynthesis in Escherichia coli.