title: Quercetin Glucoside Production by Engineered Escherichia coli.
abstract: Escherichia coli strains expressing the O-glucosyltransferases UGT73B3 or UGT84B1 were compared for the production of glucosides from quercetin supplied into a defined medium. The formation of quercetin-3-glucoside (Q3G) by UGT73B3 showed a maximum at 33 °C, while the formation of quercetin-7-glucoside by UGT84B1 increased with increasing temperature to 37 °C. The highest concentrations of Q3G were attained by strains having a deletion in the pgi gene-coding phosphoglucose isomerase, which effectively blocked the entry of glucose-6P into the Embden-Meyerhof-Parnas pathway. Formation of Q3G was improved in 1-L controlled bioreactors compared to shake flask cultures, a result attributed to the greater oxygen transfer rate in bioreactors. Under batch conditions with 30 g/L glucose as the sole carbon source, E. coli MEC367 (MG1655 pgi) expressing UGT73B3 generated 3.9 g/L Q3G in 56 h.
authors.affiliation: BioChemical Engineering, College of Engineering, University of Georgia, Athens, GA, 30602, USA.
authors.forename: Tian
authors.initials: T
authors.lastname: Xia
authors.affiliation: BioChemical Engineering, College of Engineering, University of Georgia, Athens, GA, 30602, USA. eiteman@engr.uga.edu.
authors.forename: Mark A
authors.initials: MA
authors.lastname: Eiteman
mesh_terms: D019149:Bioreactors / Q000382:microbiology; D004926:Escherichia coli / Q000235:genetics* / Q000378:metabolism*; D005818:Genetic Engineering; D005964:Glucosyltransferases / Q000235:genetics / Q000378:metabolism; D006031:Glycosylation; D011794:Quercetin / Q000031:analogs & derivatives* / Q000096:biosynthesis / Q000378:metabolism; D013696:Temperature
chemical_list: C016527:isoquercitrin; D011794:Quercetin; D005964:Glucosyltransferases
keywords: Glucose-6-phosphate 1-dehydrogenase; Glucose-6-phosphate isomerase; Glycosylation