| 摘要 |
Xylose Fermenting Yeast Constructed Using A Modified Genome Shuffling MethodAbstractBackground: Xylose is the second most abundant carbohydrate in the lignocellulosic biomass hydrolysate. The fermentation of xylose is essential for the bioconversion of lignocelluloses to fuels and chemicals. However the wild-type strains of Saccharomyces cerevisiae are unable to utilize xylose. Many efforts have been made to construct recombinant yeast strains to enhance xylose fermentation over the past few decades. Xylose fermentation remains challenging due to the complexity of lignocellulosic biomasshydrolysate.Methods: In this study, a modified genome shuffling method was developed to improve xylose fermentation by S. cerevisiae. Recombinant yeast strains were constructed by recursive DNA shuffling with the recombination of entire genomes of P. stipitis with those ofS. cerevisiae.Results: After two rounds of genome shuffling and screening, one potential recombinant yeast strain ScF2 was obtained. It was able to utilize high concentration of xylose (100 g/L to 250 g/L xylose) and produced ethanol. The recombinant yeast ScF2 produced ethanol more rapidly than the naturally occurring xylose-fermenting yeast, P. stipitis, with improved ethanol titre and much more enhanced xylose tolerance.Conclusion: The modified genome shuffling method developed in this study was more effective and easier to operate than the traditional protoplast fusion based genome shuffling method. Recombinant yeast strain ScF2 was a promising candidate for industrial cellulosic ethanol production. In order to further enhance its xylose fermentation performance, ScF2 needs to be further improved by metabolic engineering and directed evolution.(no suitable figure) |
