Xylitol production by recombinant Saccharomyces cerevisiae expressing the Pichia stipitis and Candida shehatae XYL1 genes.
The xylose reductase gene (XYL1) was isolated from Pichia stipitis and Candida shehatae, cloned into YEp-based vectors under the control of ADH2 and PGK1 promoter/terminator cassettes and introduced into Saccharomyces cerevisiae Y294 by electroporation. Shake-flask fermentations were carried out with 5% xylose and 1% galactose, glucose or maltose as co-substrates. Xylose uptake was similar in both the recombinant strains when different co-substrates were used and slowed once the co-substrate was depleted. The recombinant strains converted xylose to xylitol with yields approaching the theoretical maxima. Xylitol production was most rapid when the co-substrate was still present. Approximately 50% of the xylose was not metabolized due to the depletion of the co-substrate.
Department of Microbiology, University of Durban-Westville, Durban, South Africa.
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Govinden
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Pillay
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van Zyl
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Pillay
D000449:Aldehyde Reductase / Q000235:genetics / Q000378:metabolism*; D001709:Biotechnology / Q000379:methods; D002175:Candida / Q000201:enzymology / Q000235:genetics*; D003470:Culture Media; D018274:Electroporation / Q000379:methods; D005818:Genetic Engineering; D010843:Pichia / Q000201:enzymology / Q000235:genetics*; D012441:Saccharomyces cerevisiae / Q000201:enzymology / Q000235:genetics* / Q000254:growth & development; D014993:Xylitol / Q000096:biosynthesis*; D014994:Xylose / Q000378:metabolism
D003470:Culture Media; D014994:Xylose; D000449:Aldehyde Reductase; D014993:Xylitol