Hexanoic acid, a six-carbon saturated fatty acid, and its derivatives can be utilized in various industrial applications including perfumes, food additives, and medicine. Production of hexanoic acid often relies on petroleum, but the increase and instability of its price have made the production of hexanoic acid through bioprocesses more attractive. Although several natural bacteria, such as Clostridium spp. or Megasphaera spp. are known to produce hexanoic acid, limited physiological information and genetic engineering tools make it difficult to re-design those biological systems. In this study, Escherichia coli was engineered to optimize the hexanoic acid production by precise flux rebalancing between acetyl-CoA and butyryl-CoA. First, E. coli native thioesterase (TesB) was replaced with acetyl-CoA transferase (ACT) from Megasphaera sp. MH which was reported recently, and the hexanoic acid titer was increased by 1.47-fold. Next, flux rebalancing was carried out by tuning E. coli acetyl-CoA acetyltransferase (AtoB) using UTR engineering. The optimal flux balanced strain showed increased hexanoic acid titer by 8.95-fold compared with the strain with maximized atoB expression. Our results demonstrate that ACT from Megasphaera sp. MH is proper enzyme for hexanoic acid synthesis, and atoB should be fine-tuned to increase hexanoic acid production

Optimization of hexanoic acid production pathway in a recombinant Escherichia coli by precise flux rebalancing using synthetic promoters and UTRs

253rd National Meeting (2017)

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