Xylose utilisation by recombinant strains of Saccharomyces cerevisiae on different carbon sources.
Autoselective xylose-utilising strains of Saccharomyces cerevisiae expressing the xylose reductase (XYL1) and xylitol dehydrogenase (XYL2) genes of Pichia stipitis were constructed by replacing the chromosomal FUR1 gene with a disrupted fur1::LEU2 allele. Anaerobic fermentations with 80 g l-1 D-xylose as substrate showed a twofold higher consumption of xylose in complex medium compared to defined medium. The xylose consumption rate increased a further threefold when 20 g l-1 D-glucose or raffinose was used as co-substrate together with 50 g l-1 D-xylose. Xylose consumption was higher with raffinose as co-substrate than with glucose (85% versus 71%, respectively) after 82 h fermentations. A high initial ethanol concentration and moderate levels of glycerol and acetic acid accompanied glucose as co-substrate, whereas the ethanol concentration gradually increased with raffinose as co-substrate with no glycerol and much less acetic acid formation.
van Zyl
W H
WH
Department of Microbiology, University of Stellenbosch, South Africa. WHVZ@maties.sun.ac.za
Eliasson
A
A
Hobley
T
T
Hahn-Hägerdal
B
B
D019342:Acetic Acid / Q000378:metabolism; D000693:Anaerobiosis; D002851:Chromatography, High Pressure Liquid; D050542:D-Xylulose Reductase; D043364:Endo-1,4-beta Xylanases; D000431:Ethanol / Q000378:metabolism; D005656:Fungal Proteins / Q000096:biosynthesis / Q000235:genetics; D005947:Glucose / Q000378:metabolism; D005990:Glycerol / Q000378:metabolism; D010957:Plasmids / Q000235:genetics; D011887:Raffinose / Q000378:metabolism; D011995:Recombination, Genetic; D012441:Saccharomyces cerevisiae / Q000201:enzymology / Q000235:genetics / Q000378:metabolism*; D013401:Sugar Alcohol Dehydrogenases / Q000096:biosynthesis / Q000235:genetics; D013997:Time Factors; D014994:Xylose / Q000378:metabolism*; D014995:Xylosidases / Q000096:biosynthesis / Q000235:genetics
D005656:Fungal Proteins; D000431:Ethanol; D014994:Xylose; D013401:Sugar Alcohol Dehydrogenases; D050542:D-Xylulose Reductase; D014995:Xylosidases; D043364:Endo-1,4-beta Xylanases; C121995:xyl1 xylanase; D005947:Glucose; D011887:Raffinose; D005990:Glycerol; D019342:Acetic Acid