The Effect of Co-expression of UdhA and Candida boidinii xylI Gene on Xylitol Fermentation

TANG Mei;CAI Song;FU Sheng-liang;Hubei Key Laboratory of Industrial Microbiology, Hubei University of Technology;

Candida boydingii;;xylI gene;;UdhA gene;;Co-expression;;Xylitol

[Objective] The effect of co-expression of soluble pyridine nucleotide transhydrogenase gene(UdhA) and aldose reductase gene(xylI) on xylitol fermentation was investigated. [Method] xylI gene from Candida boidinii encoding aldose reductase was cloned into pET28 a(+) and expressed in BL21(DE3). The enzyme molecular weight was detected by SDS-PAGE and enzyme activity was assayed. xylI gene was ligated to the lacP promoter for construction of plasmid pWYZ-2 and then the plasmid was transformed into E.coli AI07.The UdhA gene derived from E.coli W3110 was further cloned into pWYZ-2 plasmid to achieve co-expression with xylI for pWYZ-4 plasmid construction and then pWYZ-4 was transformed into E.coli AI07. E.coli AI07/pWYZ-2 was compared with E.coli AI07/pWYZ-4 for xylitol fermentation.[Result] The molecular weight of xylose reductase expressed in BL21(DE3)/pET28 a(+) system was 39 kD, and the enzymatic activity of aldose reductase was 3.3 U/mL.The E.coli AI07/pWYZ-2 strain was fermented for 48 hours, the xylitol output was 19.90 g/L. E.coli AI07/pWYZ-4 was fermented for 36 hours, xylitol production reached 19.91 g/L, xylitol productivity of E.coli AI07/pWYZ-4 was 33.25% higher than that of strain E.coli AI07/pWYZ-2.[Conclusion]Xylitol productivity of recombinant Escherichia coli was improved using co-expression of UdhA gene and xylI gene.