title: Metabolic Engineering of Escherichia coli for Astragalin Biosynthesis.
abstract: Astragalin (kaempferol 3-O-glucoside) is used as a standard to assess the quality of Radix astragali and has exhibited a number of biological properties. In this work, we screened several UDP-dependent glycosyltransferases (UGT) for their potential as efficient biocatalysts for astragalin synthesis. The highest astragalin production with 285 mg/L was detected in the recombinant strain expressing UGT from Arabidopis thaliana (AtUGT78D2). To further improve astragalin production, an efficient UDP-glucose synthesis pathway was reconstructed in the recombinant strain by introducing sucrose permease, sucrose phosphorylase, and uridylyltransferase. On the basis of those results, a recombinant strain, BL21-II, was constructed to produce astragalin. By optimizing conversion conditions, astragalin production was increased from 570 to 1708 mg/L. The production was scaled up using a fed-batch fermentation, and maximal astragalin production was 3600 mg/L, with a specific productivity of 150 mg/L/h after 24 h incubation and a corresponding molar conversion of 91.9%, the highest yield reported to date.
authors.affiliation: Co-Innovation Center for Sustainable Forestry in Southern China, Nanjing Forestry University , Nanjing, China.|College of Chemical Engineering, Nanjing Forestry University , Nanjing, China.|Jiangsu Key Lab of Biomass Based Green Fuels and Chemicals, Nanjing, China.
authors.forename: Jianjun
authors.initials: J
authors.lastname: Pei
authors.affiliation: Co-Innovation Center for Sustainable Forestry in Southern China, Nanjing Forestry University , Nanjing, China.|College of Chemical Engineering, Nanjing Forestry University , Nanjing, China.
authors.forename: Ping
authors.initials: P
authors.lastname: Dong
authors.affiliation: Co-Innovation Center for Sustainable Forestry in Southern China, Nanjing Forestry University , Nanjing, China.|College of Chemical Engineering, Nanjing Forestry University , Nanjing, China.
authors.forename: Tao
authors.initials: T
authors.lastname: Wu
authors.affiliation: Co-Innovation Center for Sustainable Forestry in Southern China, Nanjing Forestry University , Nanjing, China.|College of Chemical Engineering, Nanjing Forestry University , Nanjing, China.|Jiangsu Key Lab of Biomass Based Green Fuels and Chemicals, Nanjing, China.
authors.forename: Linguo
authors.initials: L
authors.lastname: Zhao
authors.affiliation: Co-Innovation Center for Sustainable Forestry in Southern China, Nanjing Forestry University , Nanjing, China.|College of Chemical Engineering, Nanjing Forestry University , Nanjing, China.|Jiangsu Key Lab of Biomass Based Green Fuels and Chemicals, Nanjing, China.
authors.forename: Xianying
authors.initials: X
authors.lastname: Fang
authors.affiliation: Co-Innovation Center for Sustainable Forestry in Southern China, Nanjing Forestry University , Nanjing, China.|College of Chemical Engineering, Nanjing Forestry University , Nanjing, China.
authors.forename: Fuliang
authors.initials: F
authors.lastname: Cao
authors.affiliation: International Centre for Bamboo and Rattan, Beijing, China.
authors.forename: Feng
authors.initials: F
authors.lastname: Tang
authors.affiliation: International Centre for Bamboo and Rattan, Beijing, China.
authors.forename: Yongde
authors.initials: Y
authors.lastname: Yue
keywords: UDP-dependent glycosyltransferase; UDP-glucose; astragalin; flavonoid-O-glycoside; metabolic engineering