Engineered Polyploid Yeast Strains Enable Efficient Xylose Utilization and Ethanol Production in Corn Hydrolysates

Area of Science:

• Biotechnology
• Metabolic Engineering
• Yeast Fermentation

Background:

• Saccharomyces cerevisiae is a key organism for bioethanol production.
• Efficient utilization of xylose, a major component of lignocellulosic biomass, remains a challenge.
• Genetic modification of xylose utilization pathways is crucial for enhancing ethanol yields.

Purpose of the Study:

• To improve xylose utilization and ethanol production in Saccharomyces cerevisiae.
• To investigate the impact of specific mutations (XR-K270R) on fermentation performance.
• To evaluate the effect of ploidy (haploid, diploid, triploid) on ethanol yield.

Main Methods:

• Introduction of XR and XDH gene mutations into Saccharomyces cerevisiae F106.
• Construction and comparison of haploid, diploid, and triploid strains.
• Fermentation trials using simulated and non-detoxicated corn hydrolysates at varying conditions.

Main Results:

• The XR-K270R mutant demonstrated superior performance.
• Diploid and triploid strains exhibited higher ethanol yields compared to haploid strains.
• Triploid strains achieved a sevenfold increase in ethanol yield from corncob hydrolysate at 40°C compared to diploid strains.
• Consistently higher ethanol yields were observed for triploid strains using acid-pretreated corn stover hydrolysates.

Conclusions:

• Increased yeast chromosomal copy number positively correlates with enhanced ethanol production.
• Engineered triploid Saccharomyces cerevisiae strains offer a promising platform for efficient lignocellulosic bioethanol production.
• The XR-K270R mutation is beneficial for xylose utilization and ethanol fermentation.