Biomass Energy Technology Research Centre, Key Laboratory of Development and Application of Rural Renewable Energy (Ministry of Agriculture and Rural Affairs), Biogas Institute of Ministry of Agriculture and Rural Affairs, Section 4-13, Renmin Rd. South, Chengdu, 610041, China.
Institute of Ecological Environment, Chengdu University of Technology, No. 1, East Third Road, Erxian Bridge, Chenghua District, Chengdu, 610059, China.
Appl Microbiol Biotechnol. 2021 Feb;105(4):1709-1720. doi: 10.1007/s00253-021-11091-7. Epub 2021 Jan 29.
Biological ethylene production is a promising sustainable alternative approach for fossil-based ethylene production. The high glucose utilization of Z. mobilis makes it as a promising bioethylene producer. In this study, Zymomonas mobilis has been engineered to produce ethylene through the introduction of the synthetic ethylene-forming enzyme (EFE). We also investigated the effect of systematically knocking out the competitive metabolic pathway of pyruvate in an effort to improve the availability of pyruvate for ethylene production in Z. mobilis expressing EFE. Guided by these results, we tested a number of conjectures that could improve the α-ketoglutarate supply. Optimization of these pathways and different substrate supplies resulted in a greater production of ethylene (from 1.36 to 12.83 nmol/OD/mL), which may guide future engineering work on ethylene production using other organisms. Meanwhile, we achieved an ethylene production of 5.8 nmol/OD/mL in the ZM532-efe strain using enzymatic straw hydrolysate of corn straw as the sole carbon source. As a preferred host in biorefinery technologies using lignocellulosic biomass as feedstock, heterologous expression of EFE in Z. mobilis converts the non-ethylene producing strain into an ethylene-producing one using a metabolic engineering approach, which is of great significance for the utilization of cellulosic biomass in the future. KEY POINTS: • Heterologous expression of EFE in Z. mobilis successfully converted the non-ethylene producing strain into an ethylene producer (1.36 nmol/OD/mL). Targeted modifications of the central carbon metabolism can effectively improve ethylene production (peak production: 8.3 nmol/OD/mL). • The addition of nutrients to the medium can further increase the production of ethylene (peak production: 12.8 nmol/OD/mL). • The ZM532-efe strain achieved an ethylene production of 5.8 nmol/OD/mL when enzymatic hydrolysate of corn straw was used as the sole carbon source.
生物乙烯生产是一种有前途的可持续替代化石基乙烯生产的方法。运动发酵单胞菌对葡萄糖的高利用率使其成为有前途的生物乙烯生产菌。在本研究中，通过引入合成乙烯形成酶（EFE），对运动发酵单胞菌进行了工程改造以生产乙烯。我们还研究了系统敲除丙酮酸竞争代谢途径对提高表达 EFE 的运动发酵单胞菌中丙酮酸用于生产乙烯的有效性的影响。根据这些结果，我们测试了许多可以改善α-酮戊二酸供应的假设。这些途径和不同底物供应的优化导致乙烯产量增加（从 1.36 到 12.83 nmol/OD/mL），这可能为使用其他生物体生产乙烯的未来工程工作提供指导。同时，我们使用玉米秸秆酶解液作为唯一碳源，在 ZM532-efe 菌株中实现了 5.8 nmol/OD/mL 的乙烯产量。作为木质纤维素生物质为原料的生物炼制技术的首选宿主，在运动发酵单胞菌中异源表达 EFE 通过代谢工程方法将非乙烯产生菌株转化为乙烯产生菌株，这对于未来纤维素生物质的利用具有重要意义。 关键点： • 在运动发酵单胞菌中成功异源表达 EFE，将非乙烯产生菌株转化为乙烯产生菌株（1.36 nmol/OD/mL）。 • 对中心碳代谢的靶向修饰可以有效提高乙烯产量（最高产量：8.3 nmol/OD/mL）。 • 在培养基中添加营养物质可以进一步提高乙烯产量（最高产量：12.8 nmol/OD/mL）。 • 当使用玉米秸秆酶解液作为唯一碳源时，ZM532-efe 菌株实现了 5.8 nmol/OD/mL 的乙烯产量。
