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KMID : 0545120000100040496
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Journal of Microbiology and Biotechnology
2000 Volume.10 No. 4 p.496 ~ p.501
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Metabolic Flux Distribution in a Metabolically Engineered Escherichia coli Strain Producing Succinic Acid
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Hong Soon-Ho
Lee Sang-Yup
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Abstract
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Escherichia coli NZN111, which is known as a pfl ldhA double mutant strain, was metabolically engineered to produce succinic acid by overexpressing malic enzyme into the E. coli controlled by a trc promoter. Fermentation studies were carried out in a LB medium by first growing cells aerobically to an OD_600 of 5. At this point, 0.01mM IPTG was added to induce the overexpression of malic enzyme and the agitation speed was gradually lowered. When the culture OD_600, reached 11, a complete anaerobic condition was achieved by flushing with a CO_2-H_2 gas mixture. When NZN111 (pTrcML) was cultured at 37℃ the final succinic acid concentration of 2.8g/l could be obtained after 30h of anaerobic cultivation. The fermentation results were analyzed by the calculation of metabolic fluxes. Metabolic flux analysis showed that about 85% of phosphoenolpyruvate (PEP) was converted to pyruvate, and further converted to malic acid by malic enzyme.
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