Threonine is an important feed amino acid with increasing demand. Improving threonine productivity and glucose conversion rate and reducing the production costs have become an important subject. In this study, Escherichia coli THRD, a threonine-producing strain, was used to study the effects of different transcription levels of nine genes involved in central metabolic pathway on threonine synthesis by using clustered regularly interspaced short palindromic repeats interference (CRISPRi). The results showed that the transcriptional interference of genes zwf, pfkA, and gltA improved the synthesis efficiency of threonine. The threonine titers of corresponding strains were 60.3, 64.6, and 65.8 g/L, respectively, which were increased by 18.5%, 26.9%, and 29.3%, respectively, compared with the original strain (50.9 g/L). The glucose conversion rates were 40%, 38%, and 39%, respectively, which were 17.7%, 11.8%, and 14.7% higher than that of the original strain (34%). The results showed that by modifying transcriptional levels of genes that involved in central metabolism by CRISPRi could regulate the cellular metabolic network and redirect more carbon flux to threonine, resulted improved synthesis efficiency of threonine. Overall, this study provides a reference for constructing other bioengineered bacteria.
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