Department of Chemical and Biomolecular Engineering, National University of Singapore, Singapore.
Department of Chemical Engineering and Applied Chemistry, University of Toronto, Canada.
Metab Eng. 2023 Sep;79:38-48. doi: 10.1016/j.ymben.2023.06.012. Epub 2023 Jun 29.
Microbial overproduction of aromatic chemicals has gained considerable industrial interest and various metabolic engineering approaches have been employed in recent years to address the associated challenges. So far, most studies have used sugars (mostly glucose) or glycerol as the primary carbon source. In this study, we used ethylene glycol (EG) as the main carbon substrate. EG could be obtained from the degradation of plastic and cellulosic wastes. As a proof of concept, Escherichia coli was engineered to transform EG into L-tyrosine, a valuable aromatic amino acid. Under the best fermentation condition, the strain produced 2 g/L L-tyrosine from 10 g/L EG, outperforming glucose (the most common sugar feedstock) in the same experimental conditions. To prove the concept that EG can be converted into different aromatic chemicals, E. coli was further engineered with a similar approach to synthesize other valuable aromatic chemicals, L-phenylalanine and p-coumaric acid. Finally, waste polyethylene terephthalate (PET) bottles were degraded using acid hydrolysis and the resulting monomer EG was transformed into L-tyrosine using the engineered E. coli, yielding a comparable titer to that obtained using commercial EG. The strains developed in this study should be valuable to the community for producing valuable aromatics from EG.
微生物过量生产芳香化学品引起了工业界的广泛关注，近年来，人们采用了各种代谢工程方法来应对相关挑战。迄今为止，大多数研究都使用糖（主要是葡萄糖）或甘油作为主要碳源。在本研究中，我们使用乙二醇（EG）作为主要碳底物。EG 可以从塑料和纤维素废物的降解中获得。作为概念验证，我们对大肠杆菌进行了工程改造，使其能够将 EG 转化为 L-酪氨酸，这是一种有价值的芳香族氨基酸。在最佳发酵条件下，该菌株从 10g/L 的 EG 中生产出 2g/L 的 L-酪氨酸，优于相同实验条件下的葡萄糖（最常见的糖原料）。为了证明 EG 可以转化为不同的芳香族化学品的概念，我们还采用类似的方法对大肠杆菌进行了工程改造，以合成其他有价值的芳香族化学品，L-苯丙氨酸和对香豆酸。最后，使用酸水解降解废弃的聚对苯二甲酸乙二醇酯（PET）瓶，并用工程化的大肠杆菌将得到的单体 EG 转化为 L-酪氨酸，其产量与使用商业 EG 时相当。本研究中开发的菌株应该对社区从 EG 生产有价值的芳香族化合物具有重要价值。
