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영어

Flavonoids are a group of polyphenolic compounds that have been recognized as important due to their physiological and pharmacological roles and their health benefits. Glycosylation of flavonoids has a wide range of effects on flavonoid solubility, stability, and bioavailability. We previously generated the E. coli BL21 (DE3) Δpgi host by deleting the glucose-phosphate isomerase (Pgi) gene in E. coli BL21 (DE3). This host was further engineered for whole-cell biotransformation by integration of galU from E. coli K12, and expression of calS8 (UDP-glucose dehydrogenase) and calS9 (UDP-glucuronic acid decarboxylase) from Micromonospora echinospora spp. calichensis and arGt-4 (7-O-glycosyltransferase) from Arabidopsis thaliana to form E. coli (US89Gt-4), which is expected to produce glycosylated flavonoids. To test the designed system, the engineered host was fed naringenin as a substrate, and naringenin 7-O-xyloside, a glycosylated naringenin product, was detected. Product formation was verified by HPLC-LC/MS and ESI-MS/MS analyses. The reconstructed host can be applied for the production of various classes of glycosylated flavonoids. A whole-cell biotransformation system was designed in E. coli BL21 (DE3) Δpgi by integrating galU (glucose-1-phosphate uridylyltransferase) from E. coli K12, expressing calS8 (UDP-D-glucose dehydrogenase) and calS9 (UDP-D-glucuronic acid decarboxylase) from Micromonospora echinospora spp. calichensis and arGt-3 (3-O-glycosyltransferase) from Arabidopsis thaliana to form an engineered host, E. coli (US89Gt-3), for the production of glycosylated flavonoids when exogenously fed with flavonoids. To verify the system, quercetin was fed and a glycosylated product, quercetin 3-O-glucuronide, was produced but unable to produce quercetin 3-O-xyloside.