Decreased xylitol formation during xylose fermentation in Saccharomyces cerevisiae due to overexpression of water-forming NADH oxidase

Appl Environ Microbiol. 2012 Feb;78(4):1081-6. doi: 10.1128/AEM.06635-11. Epub 2011 Dec 9.

Abstract

The recombinant xylose-fermenting Saccharomyces cerevisiae strain harboring xylose reductase (XR) and xylitol dehydrogenase (XDH) from Scheffersomyces stipitis requires NADPH and NAD(+), creates cofactor imbalance, and causes xylitol accumulation during growth on d-xylose. To solve this problem, noxE, encoding a water-forming NADH oxidase from Lactococcus lactis driven by the PGK1 promoter, was introduced into the xylose-utilizing yeast strain KAM-3X. A cofactor microcycle was set up between the utilization of NAD(+) by XDH and the formation of NAD(+) by water-forming NADH oxidase. Overexpression of noxE significantly decreased xylitol formation and increased final ethanol production during xylose fermentation. Under xylose fermentation conditions with an initial d-xylose concentration of 50 g/liter, the xylitol yields for of KAM-3X(pPGK1-noxE) and control strain KAM-3X were 0.058 g/g xylose and 0.191 g/g, respectively, which showed a 69.63% decrease owing to noxE overexpression; the ethanol yields were 0.294 g/g for KAM-3X(pPGK1-noxE) and 0.211 g/g for the control strain KAM-3X, which indicated a 39.33% increase due to noxE overexpression. At the same time, the glycerol yield also was reduced by 53.85% on account of the decrease in the NADH pool caused by overexpression of noxE.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Ethanol / metabolism
  • Fermentation
  • Gene Expression
  • Lactococcus lactis / enzymology
  • Lactococcus lactis / genetics
  • Metabolic Engineering / methods
  • Multienzyme Complexes / genetics
  • Multienzyme Complexes / metabolism*
  • NADH, NADPH Oxidoreductases / genetics
  • NADH, NADPH Oxidoreductases / metabolism*
  • Promoter Regions, Genetic
  • Recombinant Proteins / genetics
  • Recombinant Proteins / metabolism
  • Saccharomyces cerevisiae / enzymology*
  • Saccharomyces cerevisiae / metabolism*
  • Water / metabolism
  • Xylitol / metabolism*
  • Xylose / metabolism*

Substances

  • Multienzyme Complexes
  • Recombinant Proteins
  • Water
  • Ethanol
  • Xylose
  • NADH oxidase
  • NADH, NADPH Oxidoreductases
  • Xylitol