Chi Junxi, Wang Pengju, Ma Yidan, Zhu Xingmiao, Zhu Leilei, Chen Ming, Bi Changhao, Zhang Xueli
College of Biological Engineering, Dalian Polytechnic University, Dalian, China.
Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin, China.
Biotechnol Biofuels Bioprod. 2024 Sep 13;17(1):121. doi: 10.1186/s13068-024-02568-4.
From both economic and environmental perspectives, ethylene glycol, the principal constituent in the degradation of PET, emerges as an optimal feedstock for microbial cell factories. Traditional methods for constructing Escherichia coli chassis cells capable of utilizing ethylene glycol as a non-sugar feedstock typically involve overexpressing the genes fucO and aldA. However, these approaches have not succeeded in enabling the exclusive use of ethylene glycol as the sole source of carbon and energy for growth. Through ultraviolet radiation-induced mutagenesis and subsequent laboratory adaptive evolution, an EG02 strain emerged from E. coli MG1655 capable of utilizing ethylene glycol as its sole carbon and energy source, demonstrating an uptake rate of 8.1 ± 1.3 mmol/gDW h. Comparative transcriptome analysis guided reverse metabolic engineering, successfully enabling four wild-type E. coli strains to metabolize ethylene glycol exclusively. This was achieved through overexpression of the gcl, hyi, glxR, and glxK genes. Notably, the engineered E. coli chassis cells efficiently metabolized the 87 mM ethylene glycol found in PET enzymatic degradation products following 72 h of fermentation. This work presents a practical solution for recycling ethylene glycol from PET waste degradation products, demonstrating that simply adding M9 salts can effectively convert them into viable raw materials for E. coli cell factories. Our findings also emphasize the significant roles of genes associated with the glycolate and glyoxylate degradation I pathway in the metabolic utilization of ethylene glycol, an aspect frequently overlooked in previous research.
从经济和环境的角度来看，聚对苯二甲酸乙二酯（PET）降解的主要成分乙二醇，成为微生物细胞工厂的理想原料。传统的构建能够将乙二醇作为非糖类原料利用的大肠杆菌底盘细胞的方法，通常涉及过表达fucO和aldA基因。然而，这些方法未能成功实现仅以乙二醇作为生长的唯一碳源和能源。通过紫外线辐射诱变及随后的实验室适应性进化，从大肠杆菌MG1655中获得了EG02菌株，该菌株能够将乙二醇作为其唯一的碳源和能源，摄取速率为8.1±1.3 mmol/gDW h。比较转录组分析指导反向代谢工程，成功使四种野生型大肠杆菌菌株能够专门代谢乙二醇。这是通过过表达gcl、hyi、glxR和glxK基因实现的。值得注意的是，经过72小时发酵后，工程化的大肠杆菌底盘细胞能够有效代谢PET酶解产物中发现的87 mM乙二醇。这项工作为从PET废料降解产物中回收乙二醇提供了一种切实可行的解决方案，表明简单地添加M9盐可以有效地将它们转化为大肠杆菌细胞工厂的可行原料。我们的研究结果还强调了与乙醇酸和乙醛酸降解I途径相关的基因在乙二醇代谢利用中的重要作用，这是先前研究中经常被忽视的一个方面。
