Growth Charicteristics Of Eschrichia Coli Which Reduce CO₂Evolution During Aerobic Fermentation

To reduce the CO₂evolution and improve the utilization efficiency of carbonsource during the industrial E.coli fermentation processes is one of the importantaspects of application research. However, the present study focused on the C4compounds such as succinic acid biosynthesis, the CO₂emission reduction problem inE.coli is ignored. The growth process of wild E.coli is accompanied by the emissionof CO₂, which is irreversible, whereas it is nessessary to construct CO₂emissionchassis E.coli and reduce the CO₂emission during the large-scale industrialfermentation through synthetic biology.Analytic comparision of the growth charactersistics such as CO₂evoluion,biomass, residual glucose, acetate, lactate, succinate and citrate, pH, dissovlvedoxygen, TOC et al. of starting strain and engineering strains during the fermentation,analyze the attribution of different genes （icd, ptsG, ppc, zwf） knockout orover-expression to the bacterial growth and the carbon utilization plus emissionreduction, perform the total carbon calculation and finally explain the principlemechanism of CO₂reduction evolution in chasis E.coli. Experiment results showedthat the engineering strain BPEC28has the lowest specific CO₂evolution rate whichis0.222(mM DCW^-1h^-1), compared with the starting strain the specific CO₂evolutionrate decreasd by84%, meanwhile the biomass formation rate is highest which is2.012[g DCW（g substrate）^-1], compared with the starting strain the biomass formationrate is increased by67.86%; Engineering strain BPEC26has the highest specificsuccinate production rate which is0.053g gDCW^-1h^-1, the specific succinate productionrate of BPEC26is3.08folders of the starting strain. The data show that the knockoutof genes icd and ptsG plus the over-expression of ppc could dramatically reduce theCO₂evolution during the aerobic fermentation and maintain good growth state.Analyse the different percentage of element such as C, H and N, perform thepreliminary analysis of intracellular metabolits, choose a proper dynamic equation andestablished the growh dynamic model, production generation dynamic model and thesubstrate consumption dynamic model of the CO₂reduction evolution in the chassisE.coli. The element analysis date show that the strain BPEC28has the lowes C% which is42.94（±0.02）, compared with the startin strain the C%of BPEC28isreduced by7.10%, meanwhile the engineering strain BPEC28has the highest N%which is13.78（±0.05）, compared with the startin strain the N%of BPEC28isreduced by5.84%. We constructed the initial relationship between primary glucosemetabolism and growth metabolism which lay a foundation of further study on themetabolic control.