Reduced oxidative pentose phosphate pathway flux in recombinant xylose-utilizing Saccharomyces cerevisiae strains improves the ethanol yield from xylose
| Autor: | Marie-Francoise Gorwa-Grauslund, Marie Jeppsson, Bärbel Hahn-Hägerdal, Björn Johansson |
|---|---|
| Jazyk: | angličtina |
| Rok vydání: | 2002 |
| Předmět: |
Saccharomyces cerevisiae
Xylose Pentose phosphate pathway Biology Xylitol Applied Microbiology and Biotechnology genetics [Xylose] Industrial Biotechnology Fungal Proteins Pentose Phosphate Pathway chemistry.chemical_compound Xylose metabolism Genetic metabolism [Ethanol] genetics [Pentosephosphate Pathway] Ethanol metabolism methods [Genetic Engineering] Non-U.S. Gov't Recombination Genetic Ecology Ethanol food and beverages enzymology [Saccharomyces cerevisiae] metabolism [Fungal Proteins] Physiology and Biotechnology Recombination carbohydrates (lipids) chemistry Biochemistry genetics [Fungal Proteins] Fermentation genetics [Saccharomyces cerevisiae] metabolism [Xylose] NAD+ kinase Support Genetic Engineering Flux (metabolism) Oxidation-Reduction Food Science Biotechnology physiology [Pentosephosphate Pathway] |
| Zdroj: | Applied and Environmental Microbiology; 68(4), pp 1604-1609 (2002) |
| ISSN: | 0099-2240 |
| Popis: | In recombinant, xylose-fermenting Saccharomyces cerevisiae , about 30% of the consumed xylose is converted to xylitol. Xylitol production results from a cofactor imbalance, since xylose reductase uses both NADPH and NADH, while xylitol dehydrogenase uses only NAD + . In this study we increased the ethanol yield and decreased the xylitol yield by lowering the flux through the NADPH-producing pentose phosphate pathway. The pentose phosphate pathway was blocked either by disruption of the GND1 gene, one of the isogenes of 6-phosphogluconate dehydrogenase, or by disruption of the ZWF1 gene, which encodes glucose 6-phosphate dehydrogenase. Decreasing the phosphoglucose isomerase activity by 90% also lowered the pentose phosphate pathway flux. These modifications all resulted in lower xylitol yield and higher ethanol yield than in the control strains. TMB3255, carrying a disruption of ZWF1, gave the highest ethanol yield (0.41 g g −1 ) and the lowest xylitol yield (0.05 g g −1 ) reported for a xylose-fermenting recombinant S. cerevisiae strain, but also an 84% lower xylose consumption rate. The low xylose fermentation rate is probably due to limited NADPH-mediated xylose reduction. Metabolic flux modeling of TMB3255 confirmed that the NADPH-producing pentose phosphate pathway was blocked and that xylose reduction was mediated only by NADH, leading to a lower rate of xylose consumption. These results indicate that xylitol production is strongly connected to the flux through the oxidative part of the pentose phosphate pathway. |
| Databáze: | OpenAIRE |
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