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Engineering an in vivo EP-bifido pathway in Escherichia coli for high-yield acetyl-CoA generation with low CO2 emission

Wang, Qian, Xu, Jiasheng, Sun, Zhijie, Luan, Yaqi, Li, Ying, Wang, Junshu, Liang, Quanfeng, Qi, Qingsheng
Metabolic engineering 2019 v.51 pp. 79-87
Escherichia coli, acetyl coenzyme A, biobased products, carbon, carbon dioxide, economics, engineering, fatty acids, fermentation, glucose, glycolysis, greenhouse gas emissions, microorganisms, pentose phosphate cycle, poly-3-hydroxybutyrate
The low carbon yield from native metabolic machinery produces unfavorable process economics during the biological conversion of substrates to desirable bioproducts. To obtain higher carbon yields, we constructed a carbon conservation pathway named EP-bifido pathway in Escherichia coli by combining Embden-Meyerhof-Parnas Pathway, Pentose Phosphate Pathway and “bifid shunt”, to generate high yield acetyl-CoA from glucose. 13C-Metabolic flux analysis confirmed the successful and appropriate employment of the EP-bifido pathway. The CO2 release during fermentation significantly reduced compared with the control strains. Then we demonstrated the in vivo effectiveness of the EP-bifido pathway using poly-β-hydroxybutyrate (PHB), mevalonate and fatty acids as example products. The engineered EP-bifido strains showed greatly improved PHB yield (from 26.0 mol% to 63.7 mol%), fatty acid yield (from 9.17% to 14.36%), and the highest mevalonate yield yet reported (64.3 mol% without considering the substrates used for cell mass formation). The synthetic pathway can be employed in the production of chemicals that use acetyl-CoA as a precursor and can be extended to other microorganisms.