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Applied Microbiology and Biotechnology

, Volume 48, Issue 2, pp 218–224 | Cite as

Expression of different levels of enzymes from the Pichia stipitis XYL1 and XYL2 genes in Saccharomyces cerevisiae and its effects on product formation during xylose utilisation

  • M. Walfridsson
  • M. Anderlund
  • X. Bao
  • B. Hahn-Hägerdal
ORIGINAL PAPER

Abstract

Saccharomyces cerevisiae was transformed with the Pichia stipitis CBS 6054 XYL1 and XYL2 genes encoding xylose reductase (XR) and xylitol dehydrogenase (XDH) respectively. The XYL1 and XYL2 genes were placed under the control of the alcohol dehydrogenase 1 (ADH1) and phosphoglycerate kinase (PGK1) promoters in the yeast vector YEp24. Different vector constructions were made resulting in different specific activities of XR and XDH. The XR:XDH ratio (ratio of specific enzyme activities) of the transformed S. cerevisiae strains varied from 17.5 to 0.06. In order to enhance xylose utilisation in the XYL1-, XYL2-containing S. cerevisiae strains, the native genes encoding transketolase and transaldolase were also overexpressed. A strain with an XR:XDH ratio of 17.5 formed 0.82 g xylitol/g consumed xylose, whereas a strain with an XR:XDH ratio of 5.0 formed 0.58 g xylitol/g xylose. The strain with an XR:XDH ratio of 0.06, on the other hand, formed no xylitol and less glycerol and acetic acid compared with strains with the higher XR:XDH ratios. In addition, the strain with an XR:XDH ratio of 0.06 produced more ethanol than the other strains.

Keywords

Xylose Saccharomyces Cerevisiae Xylitol Alcohol Dehydrogenase Pichia 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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Copyright information

© Springer-Verlag Berlin Heidelberg 1997

Authors and Affiliations

  • M. Walfridsson
    • 1
  • M. Anderlund
    • 1
  • X. Bao
    • 1
  • B. Hahn-Hägerdal
    • 1
  1. 1.Department of Applied Microbiology, Lund Institute of Technology/Lund University, P.O. Box 124, S-221 00 Lund, Sweden Tel.: +46 46 222 8428 Fax: +46 46 222 4203 e-mail: Barbel.Hahn-Hagerdal@tmb.lth.seSE

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