title: Enhanced xylitol production: Expression of xylitol dehydrogenase from Gluconobacter oxydans and mixed culture of resting cell.
abstract: Xylitol has numerous applications in food and pharmaceutical industry, and it can be biosynthesized by microorganisms. In the present study, xdh gene, encoding xylitol dehydrogenase (XDH), was cloned from the genome of Gluconobacter oxydans CGMCC 1.49 and overexpressed in Escherichia coli BL21. Sequence analysis revealed that XDH has a TGXXGXXG NAD(H)-binding motif and a YXXXK active site motif, and belongs to the short-chain dehydrogenase/reductase family. And then, the enzymatic properties and kinetic parameter of purified recombinant XDH were investigated. Subsequently, transformations of xylitol from d-xylulose and d-arabitol, respectively, were studied through mixed culture of resting cells of G. oxydans wild-type strain and recombinant strain BL21-xdh. We obtained 28.80 g/L xylitol by mixed culture from 30 g/L d-xylulose in 28 h. The production was increased by more than three times as compared with that of wild-type strain. Furthermore, 25.10 g/L xylitol was produced by the mixed culture from 30 g/L d-arabitol in 30 h with a yield of 0.837 g/g, and the max volumetric productivity of 0.990 g/L h was obtained at 22 h. These contrast to the fact that wild-type strain G. oxydans only produced 8.10 g/L xylitol in 30 h with a yield of 0.270 g/g. To our knowledge, these values are the highest among the reported yields and productivity efficiencies of xylitol from d-arabitol with engineering strains.
authors.affiliation: School of Food and Biological Engineering, Jiangsu University, Zhenjiang 212013, China. Electronic address: qxh@ujs.edu.cn.
authors.forename: Xiang-Hui
authors.initials: XH
authors.lastname: Qi
authors.affiliation: School of Food and Biological Engineering, Jiangsu University, Zhenjiang 212013, China.
authors.forename: Jing-Fei
authors.initials: JF
authors.lastname: Zhu
authors.affiliation: School of Food and Biological Engineering, Jiangsu University, Zhenjiang 212013, China.
authors.forename: Jun-Hua
authors.initials: JH
authors.lastname: Yun
authors.affiliation: School of Food and Biological Engineering, Jiangsu University, Zhenjiang 212013, China.
authors.forename: Jing
authors.initials: J
authors.lastname: Lin
authors.affiliation: College of Science and Technology, Agricultural University of Hebei, Cangzhou 061100, China.
authors.forename: Yi-Lin
authors.initials: YL
authors.lastname: Qi
authors.affiliation: School of Food and Biological Engineering, Jiangsu University, Zhenjiang 212013, China.
authors.forename: Qi
authors.initials: Q
authors.lastname: Guo
authors.affiliation: College of Food Science and Light Industry, Nanjing Tech University, Nanjing 210009, China.
authors.forename: Hong
authors.initials: H
authors.lastname: Xu
mesh_terms: D003001:Cloning, Molecular; D050542:D-Xylulose Reductase / Q000737:chemistry / Q000235:genetics* / Q000302:isolation & purification / Q000378:metabolism*; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism*; D020600:Gluconobacter oxydans / Q000201:enzymology* / Q000235:genetics; D007700:Kinetics; D060847:Metabolic Engineering; D009243:NAD / Q000378:metabolism; D013402:Sugar Alcohols / Q000378:metabolism; D014993:Xylitol / Q000096:biosynthesis*; D014996:Xylulose / Q000378:metabolism
chemical_list: D013402:Sugar Alcohols; D009243:NAD; D014996:Xylulose; D050542:D-Xylulose Reductase; D014993:Xylitol; C014999:arabitol
keywords: Gluconobacter oxydans; Mixed culture; Resting cell; Xylitol; Xylitol dehydrogenase