earticle

영어

To diversify the therapeutic uses of quercetin, Escherichia coli was exploited as a production factory, by assembly of various bacterial and plant UDP-xylose sugar biosynthetic genes and glycosyltransferase. The genes encoding for the UDP-xylose pathway enzymes phosphoglucomutase (nfa44530), glucose-1-phosphate uridylyltransferase (galU), UDP-glucose dehydrogenase (calS8), and UDP-glucuronic acid decarboxylase (calS9) were over-expressed in E. coli BL21 (DE3) along with a glycosyltransferase (arGt-3) from Arabidopsis thaliana. Furthermore, E. coli BL21 (DE3)/Δpgi, E. coli BL21 (DE3)/Δzwf, E. coli BL21 (DE3)/ΔpgiΔzwf, and E. coli BL21 (DE3)/ΔpgiΔzwfΔushA mutants carrying the aforementioned UDP-xylose sugar biosynthetic genes and glycosyltransferase, and galU integrated E. coli BL21 (DE3)/Δpgi host harboring only calS8, calS9, and arGt-3 were constructed to enhance whole cell bioconversion of exogeneously supplied quercetin into 3-O-xylosyl quercetin. The highest production of 3-O-xylosyl quercetin was achieved with E. coli BL21 (DE3)/ ΔpgiΔzwfΔushA carrying UDP-xylose sugar biosynthetic genes and glycosyltransferase. The maximum concentration of 3-O-xylosyl quercetin achieved was 23.78 mg/L (54.75 μM) representing 54.75 % bioconversion, which was ~4.8-fold higher bioconversion than that shown by E. coli BL21 (DE3) with the same set of genes when the reaction was carried out in 5 ml culture tubes with 100 μM quercetin under optimized conditions. Bioconversion was further improved by 98% when the reaction was scaled up in a 3 L fermentor at 36 h.