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Sanghak CHA,Hyun Gyu LIM,Seokmu KWON,Dong-hwan KIM,Chae Won KANG,Gyoo Yeol JUNG 한국생물공학회 2021 한국생물공학회 학술대회 Vol.2021 No.10
Carbon monoxide (CO) is a promising carbon source to produce value-added biochemicals via microbial fermentation. However, its bio-conversion has been challenging due to difficulties in genetic engineering of CO-utilizing microorganisms and, more importantly, maintaining CO consumption which is negatively affected by the toxicity of CO and accumulated byproducts. To overcome these issues, we devised mutualistic microbial consortia, consisting of Eubacterium limosum and genetically engineered Escherichia coli for the production of 3-hydroxypropionic acid (3-HP) and itaconic acid (ITA). During the co-culture, E. limosum assimilated CO and produced acetate, a toxic by-product, while E. coli utilized acetate as a sole carbon source. We found that this mutualistic interaction dramatically stabilized and improved CO consumption of E. limosum compared to its monoculture. Consequently, the improved CO consumption allowed successful production of 3-HP and ITA from CO. This study is the first demonstration of value-added biochemical production from CO using a microbial consortium. Moreover, it suggests that synthetic mutualistic microbial consortium can serve as a powerful platform for the valorization of CO.
Plug-in Repressor Library for Fine-tuning of Metabolic Flux in Escherichia coli
Ji Yeon LEE,Sanghak CHA,Ji Hoon LEE,Hyun Gyu LIM,Myung Hyun NOH,Chae won KANG,Gyoo Yeol JUNG 한국생물공학회 2021 한국생물공학회 학술대회 Vol.2021 No.10
In metabolic engineering, enhanced production of value-added chemicals requires precise flux control between growth-essential competing and production pathways. Although advances in synthetic biology have facilitated the exploitation of a number of genetic elements for precise flux control, their use requires expensive inducers, or more importantly, needs complex and time-consuming processes to design and optimize appropriate regulator components, case-by-case. To overcome this issue, we devised the plug-in repressor libraries for target-specific flux control, in which expression levels of the repressors were diversified using degenerate 5′ untranslated region (5’ UTR) sequences employing the UTR Library Designer. After we validated a wide expression range of the repressor libraries, they were applied to improve the production of lycopene from glucose and 3-hydroxypropionic acid (3-HP) from acetate in Escherichia coli via precise flux rebalancing to enlarge precursor pools. As a result, we successfully achieved optimal carbon fluxes around the precursor nodes for efficient production. The most optimized strains were observed to produce 2.59 g/L of 3-HP and 11.66 ㎎/L of lycopene, which were improved 16.5-fold and 2.82-fold, respectively, compared to those produced by the parental strains. These results indicate that carbon flux rebalancing using the plug-in library is a powerful strategy for efficient production of value-added chemicals in E. coli.