Abstract
Background: Engineering of Saccharomyces cerevisiae for the simultaneous utilization of hexose and pentose sugars is vital for cost-efficient cellulosic bioethanol production. This yeast lacks specific pentose transporters and depends on endogenous hexose transporters for low affinity pentose uptake. Consequently, engineered xylose-fermenting yeast strains first utilize D-glucose before D-xylose can be transported and metabolized.
Results: We have used an evolutionary engineering approach that depends on a quadruple hexokinase deletion xylose-fermenting S. cerevisiae strain to select for growth on D-xylose in the presence of high D-glucose concentrations. This resulted in D-glucose-tolerant growth of the yeast of D-xylose. This could be attributed to mutations at N367 in the endogenous chimeric Hxt36 transporter, causing a defect in D-glucose transport while still allowing specific uptake of D-xylose. The Hxt36-N367A variant transports D-xylose with a high rate and improved affinity, enabling the efficient co-consumption of D-glucose and D-xylose.
Conclusions: Engineering of yeast endogenous hexose transporters provides an effective strategy to construct glucose-insensitive xylose transporters that are well integrated in the carbon metabolism regulatory network, and that can be used for efficient lignocellulosic bioethanol production.
Original language | English |
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Article number | 168 |
Number of pages | 11 |
Journal | Biotechnology for Biofuels |
Volume | 7 |
Issue number | 168 |
DOIs | |
Publication status | Published - 29-Nov-2014 |
Keywords
- Sugar transporter
- Xylose transporter
- Evolutionary engineering
- Bioethanol
- Yeast
- ESCHERICHIA-COLI
- FERMENTATION
- CATABOLISM
- EXPRESSION
- BIOFUELS
- STRAIN
- GENES
- KEY