Biotransformation of quercetin to quercetin 3-O-gentiobioside using engineered Escherichia coli

Various flavonoid O -diglycosides are found in nature but the biological activities of only a few compounds have been explored due to difficulty in obtaining samples. In order to circumvent the need for extraction and purification of the natural compounds from plants, we used engineered Escherichia coli strain that harbors two uridine diphosphate-dependent glycosyltransferases (UGTs; BcGT1 and CaUGT ) and two nucleotide sugar biosynthetic genes ( pgm and galU ). Using this strain, we synthesized quercetin 3- O -gentiobioside. After optimization of induction temperature, cell density, and reaction temperature, approximately 46.2 mg/L quercetin 3- O -gentiobioside was synthesized from quercetin with 49 % conversion efficiency.