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Xylose Utilising Recombinant Saccharomyces cerevisiae strains

Walfridsson, Mats (1996)
Abstract
Through metabolic engineering, S. cerevisiae was provided with the necessary enzymes required for xylose utilisation during ethanolic fermentation of xylose-rich lignocellulose raw materials. For xylitol production, S. cerevisiae was provided with the Pichia stipitis XYL1 gene encoding xylose reductase (XR). The in-vivo reduction and the following excretion of xylitol, requires a co-substrate for maintenance and cofactor regeneration. Xylitol yields close to 100% were obtained with the XYL1 containing S. cerevisiae. Introducing P. stipitis XYL1 and XYL2 genes, encoding XR and xylitol dehydrogenase (XDH), respectively, enabled S. cerevisiae to convert xylose to xylulose, via xylitol. During the screening work of P. stipitis XDH gene,... (More)
Through metabolic engineering, S. cerevisiae was provided with the necessary enzymes required for xylose utilisation during ethanolic fermentation of xylose-rich lignocellulose raw materials. For xylitol production, S. cerevisiae was provided with the Pichia stipitis XYL1 gene encoding xylose reductase (XR). The in-vivo reduction and the following excretion of xylitol, requires a co-substrate for maintenance and cofactor regeneration. Xylitol yields close to 100% were obtained with the XYL1 containing S. cerevisiae. Introducing P. stipitis XYL1 and XYL2 genes, encoding XR and xylitol dehydrogenase (XDH), respectively, enabled S. cerevisiae to convert xylose to xylulose, via xylitol. During the screening work of P. stipitis XDH gene, another gene encoding a polyol dehydrogenase was isolated and cloned in S. cerevisiae. The gene was identified as a D-arabinitol dehydrogenase gene. In P. stipitis it may function as a redox sink by reducing D-ribulose to D-arabinitol. The metabolism through the pentose phosphate pathway (PPP) was enhanced by overexpressing the native genes TKL1 and TAL1 encoding transketolase and transaldolase, respectively, resulting in improved xylose utilisation. The XR and XDH activities in recombinant S. cerevisiae were produced at different levels by constructing yeast vectors in which the PGK1 and ADHI promoters controlled XYL1 and XYL2. With higher XDH than XR activities, less by-products, in the form of xylitol and glycerol, were formed by the recombinant S. cerevisiae strains. The Thermus thermophilus xylA gene encoding a thermostable xylose isomerase was cloned and expressed in S. cerevisiae. The recombinant xylose isomerase was actively produced and a new functional metabolic pathway was established in S. cerevisiae resulting in ethanol production from xylose. (Less)
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author
opponent
  • Prof Kielland-Brandt, Morten, Carlsberg Laboratory, Copenhagen, Denmark
publishing date
type
Thesis
publication status
published
subject
keywords
xylose isomerase, transaldolase, transketolase, xylitol dehydrogenase, xylose reductase, Thermus thermophilus, Pichia stipitis, ethanol, metabolic engineering, xylitol, Microbiology, bacteriology, virology, mycology, Mikrobiologi, bakteriologi, virologi, mykologi
pages
37 pages
publisher
Applied Microbiology (LTH)
defense location
Chemical Centre, lecture hall C, Solvegatan 39, Lund
defense date
1996-06-05 10:15
external identifiers
  • Other:ISRN: LUTKDH (TKMB-1023)115(1996)
language
English
LU publication?
no
id
e733b4cb-9307-4f1c-be65-c12dc507e93d (old id 28584)
date added to LUP
2007-06-15 08:42:21
date last changed
2016-09-19 08:45:14
@misc{e733b4cb-9307-4f1c-be65-c12dc507e93d,
  abstract     = {Through metabolic engineering, S. cerevisiae was provided with the necessary enzymes required for xylose utilisation during ethanolic fermentation of xylose-rich lignocellulose raw materials. For xylitol production, S. cerevisiae was provided with the Pichia stipitis XYL1 gene encoding xylose reductase (XR). The in-vivo reduction and the following excretion of xylitol, requires a co-substrate for maintenance and cofactor regeneration. Xylitol yields close to 100% were obtained with the XYL1 containing S. cerevisiae. Introducing P. stipitis XYL1 and XYL2 genes, encoding XR and xylitol dehydrogenase (XDH), respectively, enabled S. cerevisiae to convert xylose to xylulose, via xylitol. During the screening work of P. stipitis XDH gene, another gene encoding a polyol dehydrogenase was isolated and cloned in S. cerevisiae. The gene was identified as a D-arabinitol dehydrogenase gene. In P. stipitis it may function as a redox sink by reducing D-ribulose to D-arabinitol. The metabolism through the pentose phosphate pathway (PPP) was enhanced by overexpressing the native genes TKL1 and TAL1 encoding transketolase and transaldolase, respectively, resulting in improved xylose utilisation. The XR and XDH activities in recombinant S. cerevisiae were produced at different levels by constructing yeast vectors in which the PGK1 and ADHI promoters controlled XYL1 and XYL2. With higher XDH than XR activities, less by-products, in the form of xylitol and glycerol, were formed by the recombinant S. cerevisiae strains. The Thermus thermophilus xylA gene encoding a thermostable xylose isomerase was cloned and expressed in S. cerevisiae. The recombinant xylose isomerase was actively produced and a new functional metabolic pathway was established in S. cerevisiae resulting in ethanol production from xylose.},
  author       = {Walfridsson, Mats},
  keyword      = {xylose isomerase,transaldolase,transketolase,xylitol dehydrogenase,xylose reductase,Thermus thermophilus,Pichia stipitis,ethanol,metabolic engineering,xylitol,Microbiology,bacteriology,virology,mycology,Mikrobiologi,bakteriologi,virologi,mykologi},
  language     = {eng},
  pages        = {37},
  publisher    = {ARRAY(0x821f980)},
  title        = {Xylose Utilising Recombinant Saccharomyces cerevisiae strains},
  year         = {1996},
}