Tan Fu-Rong, Dai Li-Chun, Wu Bo, Qin Han, Shui Zong-Xia, Wang Jing-Li, Zhu Qi-Li, Hu Qi-Chun, Ruan Zhi-Yong, He Ming-Xiong
Biogas Institute of Ministry of Agriculture, Biomass Energy Technology Research Centre, Section 4-13, Renming Nanlu, Chengdu, 610041, People's Republic of China.
Appl Microbiol Biotechnol. 2015 Jun;99(12):5363-71. doi: 10.1007/s00253-015-6577-2. Epub 2015 Apr 21.
Furfural from lignocellulosic hydrolysates is the key inhibitor for bio-ethanol fermentation. In this study, we report a strategy of improving the furfural tolerance in Zymomonas mobilis on the transcriptional level by engineering its global transcription sigma factor (σ(70), RpoD) protein. Three furfural tolerance RpoD mutants (ZM4-MF1, ZM4-MF2, and ZM4-MF3) were identified from error-prone PCR libraries. The best furfural-tolerance strain ZM4-MF2 reached to the maximal cell density (OD600) about 2.0 after approximately 30 h, while control strain ZM4-rpoD reached its highest cell density of about 1.3 under the same conditions. ZM4-MF2 also consumed glucose faster and yield higher ethanol; expression levels and key Entner-Doudoroff (ED) pathway enzymatic activities were also compared to control strain under furfural stress condition. Our results suggest that global transcription machinery engineering could potentially be used to improve stress tolerance and ethanol production in Z. mobilis.
木质纤维素水解产物中的糠醛是生物乙醇发酵的关键抑制剂。在本研究中，我们报道了一种通过改造运动发酵单胞菌的全局转录sigma因子（σ(70)，RpoD）蛋白，在转录水平上提高其对糠醛耐受性的策略。从易错PCR文库中鉴定出三个耐糠醛的RpoD突变体（ZM4-MF1、ZM4-MF2和ZM4-MF3）。最佳耐糠醛菌株ZM4-MF2在约30小时后达到最大细胞密度（OD600）约2.0，而对照菌株ZM4-rpoD在相同条件下达到的最高细胞密度约为1.3。ZM4-MF2消耗葡萄糖的速度也更快，乙醇产量更高；还比较了糠醛胁迫条件下与对照菌株的表达水平和关键的Entner-Doudoroff（ED）途径酶活性。我们的结果表明，全局转录机制工程有可能用于提高运动发酵单胞菌的胁迫耐受性和乙醇产量。
