Construction of industrial xylose-fermenting Saccharomyces cerevisiae strains through combined approaches. (September 2020)

• Record Type: Journal Article
• Authors: Xie, Cai-Yun; Yang, Bai-Xue; Wu, Ya-Jing; Xia, Zi-Yuan; Gou, Min; Sun, Zhao-Yong; Tang, Yue-Qin
• Is Part Of: Process biochemistry. Volume 96(2020)
• Page Start: 80
• Page End: 89
• Publication Date: 2020-09
• Subjects: Lignocellulosic bioethanol -- Xylose fermentation -- Redox imbalance -- Evolutionary engineering -- Saccharomyces cerevisiae; Biochemical engineering -- Periodicals; Biotechnology -- Periodicals; Biochemistry -- periodicals; Biotechnology -- periodicals; Chemical Engineering -- periodicals; Génie biochimique -- Périodiques; Biotechnologie -- Périodiques; Biochemical engineering; Biotechnology; Periodicals; 660.63
• DOI: 10.1016/j.procbio.2020.05.022
• Languages: English
• ISSNs: 1359-5113

Abstract

Graphical abstract: Highlights: A combination of point mutation, mating, adaptation, and haploidization was used. Sugar uptake and ethanol production were enhanced by adaptive evolution. Evolved strains had strong tolerance to inhibitors in the pretreated straw slurry. Abstract: Saccharomyces cerevisiae strain with excellent xylose-fermenting capacity and inhibitor tolerance is crucial for lignocellulosic ethanol production. In this study, a combined strategy including site-directed mutagenesis, mating, evolutionary engineering, and haploidization was applied to obtain strains with ideal xylose fermentabilities. Haploid industrial strain KFG4-6B was engineered to overexpress endogenous xylulokinase (XK) and heterologous native or mutated xylose reductase (XR) and xylitol dehydrogenase (XDH) from Scheffersomyces stipitis . The XR-mutated strain HX57D showed over 12% increase in both xylose consumption rate and ethanol yield compared with the XR-native strain. To improve the xylose uptake, the HX57D-derived diploids were subjected to evolutionary engineering. In comparison with HX57D, evolved diploid Z4X-21-18 achieved 4.5-fold increases in rates of xylose consumption and ethanol production when fermenting xylose. When fermenting mixed sugars, the glucose and xylose uptake rates were 1.4-fold and 8.3-fold, respectively, higher. H18s28, a haploid of Z4X-21-18, enabled a further 10% increase in xylose consumption rate when fermenting xylose only. However, it was inferior to its diploid parent when fermenting mixed sugars. In the presaccharification-simultaneous saccharification and fermentation (P-SSF) of the whole pretreated wheat straw slurry with high contents of multiple inhibitors, Z4X-21-18 produced approximately 42 g/L ethanol with a yield of 0.38 g/g total sugars.