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Improving co-fermentation of glucose and xylose by adaptive evolution of engineering xylose-fermenting Saccharomyces cerevisiae and different fermentation strategies
- Li, Wen-Chao, Zhu, Jia-Qing, Zhao, Xiong, Qin, Lei, Xu, Tao, Zhou, Xiao, Li, Xia, Li, Bing-Zhi, Yuan, Ying-Jin
- Renewable energy 2019 v.139 pp. 1176-1183
- Saccharomyces cerevisiae, carbon, coculture, engineering, ethanol, evolutionary adaptation, fermentation, furfural, genetically engineered microorganisms, glucose, lignocellulose, reactive oxygen species, renewable energy sources, xylose
- Xylose utilization of engineered yeast is vulnerable to inhibitors generated during pretreatment of lignocellulose. In this study, adaptive evolution was applied to enhance the tolerance of xylose-fermenting strain. Compared to the parental strain, the ethanol yield was increased by 60% and 80% for the adapted strain (E7-403) when xylose was used as the sole carbon resource with 20% and 50% inhibitor cocktails, respectively. E7-403 removed furfural more effectively than parental strain (E7) in the fermentation with 100% inhibitor cocktails. In the fermentation with mixed sugar and high inhibitor concentration, glucose was depleted within 36 h for E7-403 while 6.1 g/L glucose was still left after 120 h for E7. Consequently, ethanol yield of E7-403 was 22.9% higher than that of E7. It was demonstrated that E7-403 strain exhibited an enhanced ability for regulating cellular reactive oxygen species, which alleviated the harmful effects of inhibitors. Meanwhile, E7-403 strain was further applied in co-culture and pre-fermentation process to improve xylose utilization.