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Optimization of hexanoic acid production in recombinant Escherichia coli by precise flux rebalancing
- Kim, Seong Gyeong, Jang, Sungho, Lim, Jae Hyung, Jeon, Byoung Seung, Kim, Jungyeon, Kim, Kyoung Heon, Sang, Byoung-In, Jung, Gyoo Yeol
- Bioresource technology 2018 v.247 pp. 1253-1257
- Cupriavidus necator, Escherichia coli, Megasphaera, acetyl coenzyme A, acetyl-CoA acetyltransferase, butyric acid, fermentation, genes, hexanoic acid, inoculum
- The aim of this study is to demonstrate that rebalancing of metabolic fluxes at acetyl-CoA branch node can substantially improve the titer and productivity of hexanoic acid in recombinant Escherichia coli strains. First, a hexanoic acid-producing E. coli strain was constructed by expressing genes encoding β-ketothiolase (BktB) from Cupriavidus necator and acetyl-CoA transferase (ACT) from Megasphaera sp. MH in a butyric acid producer strain. Next, metabolic flux was optimized at the acetyl-CoA branch node by fine-tuning the expression level of the gene for acetyl-CoA acetyltransferase (AtoB). Four synthetic 5′-untranslated regions were designed for atoB using UTR Designer to modulate the expression level of the gene. Notably, the productivity of the optimized strain (14.7 mg/L/h) was the highest among recombinant E. coli strains in literature when using a similar inoculum size for fermentation. These results show that fine-tuning the expression level of atoB is critical for production of hexanoic acid.