Metabolic engineering of Escherichia coli for the efficient production of short-chain primary amines

Abstract

Due to our heavy dependence on petrochemical-based production of chemicals and materials, we are now facing a serious climate crisis. The chemical production of many important compounds and materials is unsustainable, as fossil resources are finite and the extreme conditions required for chemical synthesis make it difficult to operate. Therefore, establishing a novel, sustainable, and environmentally friendly process for the production of chemicals and materials is receiving much attention. Developing a microbial cell factory for these purposes is now possible, thanks to emerging methods and strategies of system metabolic engineering. In this study, we developed metabolically engineered Escherichia coli strains for the efficient production of short-chain primary amines, namely ethylamine and ethanolamine, which are heavily used platform chemicals in the chemical industry. For ethylamine production, cell metabolism was optimized to increase the production of L-alanine, the precursor of ethylamine. Next, the low productivity of the key enzyme VlmDV94I was addressed by enhancing the expression of its gene. The fed-batch fermentation process was also optimized, resulting in the production of 36.3 g/L of ethylamine with the productivity of 0.432 g/L/h. For ethanolamine production, metabolic pathways were optimized to enhance the production of its precursor, L-serine. An optimal serine decarboxylase, Atsdc from Arabidopsis thaliana, was also screened among the candidate enzymes. After optimizing the fermentation process, the final strain produced 36.9 g/L of ethanolamine with the high productivity of 1.04 g/L/h. The strategies and methods used in this study can be used for development of sustainable bio-based production of different chemicals and materials.