Aromatic amines are widely used in the pharmaceutical industry. Here, we reported the establishment of a bacterial platform for synthesizing three types of aromatic amines, namely, tyramine, dopamine, and phenylethylamine. Firstly, we expressed aromatic amino acid decarboxylase from Enterococcus faecium (pheDC) in an Escherichia coli strain with an increased shikimate (SHK) pathway flux toward L-tyrosine or L-phenylalanine synthesis. We found that glycerol served as a better carbon source than glucose, resulting in 940±46 mg/L tyramine from 4% glycerol. Next, the genes of lactate dehydrogenase (ldhA), formate acetyltransferase (pflB), phosphate acetyltransferase (pta), and alcohol dehydrogenase (adhE) were deleted to mitigate the fermentation byproduct formation. The tyramine level was further increased to 1.965±0.205 g/L in shake flasks, corresponding to 2.1 times improvement compared with that of the parental strain. By using a similar strategy, we also managed to produce 703±21 mg/L dopamine and 555±50 mg/L phenethylamine. In summary, we have demonstrated that the knockout of ldhA-pflB-pta-adhE is an effective strategy in improving aromatic amine productions, and achieved the highest aromatic amine titers in E. coli under shake flasks reported to date.

中文翻译：

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在代谢工程大肠杆菌中高效生产芳香胺

芳香胺广泛用于制药工业。在这里，我们报道了一个细菌平台的建立，用于合成三种芳香胺，即酪胺、多巴胺和苯乙胺。首先，我们在大肠杆菌菌株中表达了来自屎肠球菌( pheDC ) 的芳香族氨基酸脱羧酶，其向 L-酪氨酸或 L-苯丙氨酸合成的莽草酸 (SHK) 途径通量增加。我们发现甘油作为比葡萄糖更好的碳源，从 4% 的甘油中产生 940±46 mg/L 的酪胺。接下来，乳酸脱氢酶（ldhA）、甲酸乙酰转移酶（pflB）、磷酸乙酰转移酶（pta ）的基因) 和乙醇脱氢酶 ( adhE ) 被删除以减轻发酵副产物的形成。摇瓶中酪胺水平进一步提高至1.965±0.205 g/L，相当于亲本菌株的2.1倍。通过使用类似的策略，我们还设法生产了 703±21 mg/L 多巴胺和 555±50 mg/L 苯乙胺。总之，我们已经证明了ldhA - pflB - pta - adhE的敲除是提高芳香胺产量的有效策略，并且在迄今为止报道的摇瓶下在大肠杆菌中实现了最高的芳香胺滴度。