서강대학교

초록/요약

Rapidly industry development on base petrochemical technology has caused an increment of fossil fuels usage for 20th century. Therefore, concentration of greenhouse gas in the atmosphere has been increased by continual usage of the fossil fuels. The increased concentration of greenhouse gas is a main cause to generate global climate change. Carbon dioxide (CO2) is an abundant and cheap carbon source that is mainly responsible for the global climate change. Therefore, various technology to reduction of CO2 has been developed. Carbon capture storage (CCS) and carbon capture usage (CCU) are representative technology in field of carbon capture technology. The objective of this study was to construct a recombinant E. coli strain that can show enhanced utilization of CO2 for valuable chemical. Succinic acid is a one of valuable chemical through CO2 fixation pathway in E. coli and can be used as starting chemical for other chemicals (e.g. 1,4-butanediol and adipic acid). Firstly, the carbonic anhydrase gene (SP(-)HCCA) derived from Hahella chejuensis KCTC 2396 was overexpressed to enhance carbon flux toward bicarbonate ion (HCO3-) synthesis in E. coli. The phosphoenolpyruvate carboxylase gene (ppc) was co-overexpressed to enhance the production of oxaloacetate by enhancing the carbon flux. It was confirmed the enhancement of utilization by analyzing succinic acid containing one carbon-13 (13C) derived from 13CO2. Secondly, the lactate dehydrogenase gene (ldhA) was deleted to re-direct the utilization of the carbon source from glucose to enhance succinic acid production in recombinant E. coli. Third, the phosphotransferase system gene (ptsG) or pyruvate kinase F gene (pykF) were deleted to increase the amount of phosphoenolpyruvate (PEP). Forth, deletion of multiple genes (pykF, ptsG, and pykA) was conducted to increase succinic acid biosynthesis in the recombinant E. coli. Finally, the strain, which showed the highest production of succinic acid by utilization of CO2, was cultured by batch fermentation. Additionally, effect of silica nanoparticle on gas fermentation was analyzed. From the results, it was proved that co-overexpression of the genes and multiple genes deletion may be useful for enhancing CO2 utilization in E. coli. Additionally, engineered strains showed the potential to reduce the cost of succinate production by using an industrially cheaper carbon source such as CO2 and converting CO2 to a valuable chemical.