Efficient production of d-1,2,4-butanetriol from d-xylose by engineered Escherichia coli whole-cell biocatalysts

Abstract

We have developed a whole-cell bioconversion system for the production of d-1,2,4-butanetriol (BT) from renewable biomass. A plasmid pETduet-xylB-yjhG-T7-adhP-T7-mdlC was constructed and transformed to Escherichia coli BL21(DE3) to obtain the whole cells of E. coli BL21-XYMA capable of bioconversion d-xylose to BT. Then, the factors including carbon sources, nitrogen sources, metal ions, and culture conditions (pH, temperature, IPTG) were identified, and their effects on the whole-cell activity for BT production were investigated. To obtain the highest whole-cell activity, the optimal cultivation parameters are: 15 g·L–1 yeast extract, 5 g·L–1 sucrose, 3 g·L–1 KH2PO4, 5 g·L–1 NaCl, 3 g·L–1 NH4Cl, 0.25 g·L–1 MgSO4·7H2O and 1 mL·L–1 the mixture of trace elements. With the optimized whole cells of E. coli BL21-XYMA, 60 g·L–1 of xylose was converted to 28 g·L–1 BT with a molar yield of 66 %, which is higher than those reported in the biotechnological system.