Department of Biochemical Engineering/Institute for Synthetic Biosystem, School of Chemistry and Chemical Engineering, Beijing Institute of Technology, Beijing, 100081, China.
Key Lab for Industrial Biocatalysis, Ministry of Education, Department of Chemical Engineering, Tsinghua University, Beijing, 100084, China.
Metab Eng. 2020 Sep;61:160-170. doi: 10.1016/j.ymben.2020.06.003. Epub 2020 Jun 15.
Yeast productivity in lignocellulosic ethanol fermentation is clearly impeded by stress. Enhancing the robustness of xylose-fermenting yeast is important for improving lignocellulosic ethanol production. In this study, the glutathione biosynthesis pathway and acetic acid degradation pathway were strengthened to enhance yeast tolerance to stress due to elevated reactive oxygen species (ROS) and acetic acid. Dynamic feedback regulation of the anti-stress genetic circuits was achieved using stress-driven promoters discovered from the transcriptome to maintain low intracellular ROS, relieve the metabolic burden, and ultimately improve the robustness and ethanol production of yeast. The cell growth, xylose utilization and ethanol production of the engineered strain were enhanced under both stress and nonstress conditions. The engineered strain showed 49.5% and 17.5% higher ethanol productivity in laboratory media and industrial lignocellulosic media, respectively, at 36 °C compared with the parent strain. This study provides novel insights on the rational design and construction of feedback genetic circuits for dynamically improving yeast robustness.
酵母在木质纤维素乙醇发酵中的生产力显然受到压力的阻碍。提高木糖发酵酵母的鲁棒性对于提高木质纤维素乙醇的生产非常重要。在这项研究中，通过强化谷胱甘肽生物合成途径和乙酸降解途径，增强酵母对由于活性氧（ROS）和乙酸增加而引起的应激的耐受性。通过使用从转录组中发现的应激驱动启动子来实现抗应激遗传回路的动态反馈调节，以维持低细胞内 ROS、减轻代谢负担，最终提高酵母的鲁棒性和乙醇生产能力。在应激和非应激条件下，工程菌株的细胞生长、木糖利用和乙醇生产都得到了提高。与亲本菌株相比，工程菌株在 36°C 下，在实验室培养基和工业木质纤维素培养基中的乙醇生产率分别提高了 49.5%和 17.5%。本研究为动态提高酵母鲁棒性的反馈遗传回路的合理设计和构建提供了新的见解。
