Pan Shuo, Jia Bin, Liu Hong, Wang Zhen, Chai Meng-Zhe, Ding Ming-Zhu, Zhou Xiao, Li Xia, Li Chun, Li Bing-Zhi, Yuan Ying-Jin
1Key Laboratory of Systems Bioengineering (Ministry of Education), School of Chemical Engineering and Technology, Tianjin University, Tianjin, 300072 People's Republic of China.
2SynBio Research Platform, Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), Tianjin University, Tianjin, 300072 People's Republic of China.
Biotechnol Biofuels. 2018 Apr 10;11:107. doi: 10.1186/s13068-018-1107-y. eCollection 2018.
Acetic acid, generated from the pretreatment of lignocellulosic biomass, is a significant obstacle for lignocellulosic ethanol production. Reactive oxidative species (ROS)-mediated cell damage is one of important issues caused by acetic acid. It has been reported that decreasing ROS level can improve the acetic acid tolerance of .
Lycopene is known as an antioxidant. In the study, we investigated effects of endogenous lycopene on cell growth and ethanol production of in acetic acid media. By accumulating endogenous lycopene during the aerobic fermentation of the seed stage, the intracellular ROS level of strain decreased to 1.4% of that of the control strain during ethanol fermentation. In the ethanol fermentation system containing 100 g/L glucose and 5.5 g/L acetic acid, the lag phase of strain was 24 h shorter than that of control strain. Glucose consumption rate and ethanol titer of yPS002 got to 2.08 g/L/h and 44.25 g/L, respectively, which were 2.6- and 1.3-fold of the control strain. Transcriptional changes of gene and gene confirmed that endogenous lycopene can decrease oxidative stress and improve intracellular environment.
Biosynthesis of endogenous lycopene is first associated with enhancing tolerance to acetic acid in . We demonstrate that endogenous lycopene can decrease intracellular ROS level caused by acetic acid, thus increasing cell growth and ethanol production. This work innovatively puts forward a new strategy for second generation bioethanol production during lignocellulosic fermentation.
木质纤维素生物质预处理过程中产生的乙酸是木质纤维素乙醇生产的重大障碍。活性氧（ROS）介导的细胞损伤是乙酸引起的重要问题之一。据报道，降低ROS水平可提高对乙酸的耐受性。
番茄红素是一种抗氧化剂。在本研究中，我们研究了内源性番茄红素对乙酸培养基中细胞生长和乙醇生产的影响。通过在种子阶段的好氧发酵过程中积累内源性番茄红素，菌株在乙醇发酵过程中的细胞内ROS水平降至对照菌株的1.4%。在含有100 g/L葡萄糖和5.5 g/L乙酸的乙醇发酵系统中，菌株的延迟期比对照菌株短24 h。yPS002的葡萄糖消耗率和乙醇滴度分别达到2.08 g/L/h和44.25 g/L，分别是对照菌株的2.6倍和1.3倍。基因和基因的转录变化证实，内源性番茄红素可降低氧化应激并改善细胞内环境。
内源性番茄红素的生物合成首次与提高对乙酸的耐受性相关。我们证明内源性番茄红素可降低乙酸引起的细胞内ROS水平，从而增加细胞生长和乙醇产量。这项工作创新性地提出了木质纤维素发酵过程中第二代生物乙醇生产的新策略。
