Production of flavonol and flavone 6- C -glucosides by bioconversion in Escherichia coli expressing a C -glucosyltransferase from wasabi ( Eutrema japonicum )

Objectives To produce flavonol and flavone 6- C -glucosides by bioconversion using recombinant Escherichia coli expressing a C -glucosyltransferase from wasabi (WjGT1). Results Escherichia coli expressing WjGT1 (Ec-WjGT1) converted flavones (apigenin and luteolin) and flavonols (quercetin and kaempferol) into their 6- C -glucosides in M9 minimal media supplemented with glucose, and released these products into the culture media. Ec-WjGT1 system also converts a flavanone (naringenin) into its C -glucoside at a conversion rate of 60% in 6 h. For scale-up production, apigenin, kaempferol, and quercetin were sequentially fed into the Ec-WjGT1 system at concentrations of 20–50 µM every 15–60 min, and the system was then able to produce isovitexin, kaempferol 6- C -glucoside, and quercetin 6- C -glucoside at an 89–99% conversion rate. Conclusions The Ec-WjGT1 system quickly and easily produces flavone and flavonol 6- C -glucosides at high conversion rates when using sequential administration to avoid precipitation of substrates.