Dynamic Regulation Of Ppc To Improve The Efficiency Of Succinic Acid Synthesis

Succinic Acid(SA)is an important chemical product and widely employed in the bio-polymer,food,agriculture,medicine,fine chemicals industries with a huge potential market.SA Production by anaerobic fermentation using wild-type Escherichia coli strains resulted in the formation of a large number of by-products.Construction of recombinant E.coli with higher yields of butanedioic acid by genetic engineering method is currently a hot research topic.In this study,the strategy of temperature control switch and optimization of two-phase fermentation was used to enhance the yield of SA.Main results are as follows:To over express ppc,the promoter of ppc of the recombinant strain E.coli B0013-025 was replaced by cIts857-PR-PL.The relative activity of PPC from B0013-026 is higher than B0013-025 after induced at 42?.The growth of B0013-026 is limited when glucouse is the only carbon source and cultured at 30?.The recombinant strains B0013-025 and recombinant B0013-026 were cultured under limited oxygen based on glucose M9 media and found that the accumulation of SA is 1.3 times higher than B0013-025.It proved that cIts857-PR-PL works well under the levels of growth and fermentation.Carbon substrate,growth temperature,induction and condition of oxygen supply were optimized in the two-phase fermentation.The optimum conditions for the production of SA were as follows:For strain B0013-026,growth at 37?,induction at 42? and with glycerol(20 g/L)as the sole carbon source and tryptone(5 g/L)as organic nitrogen under the micro-aerobic conditions,the highest conversion rate of glycerol to SA was 69.1%.The production of succinate is 51 g/L by refilling glycerol in the fermentation process.The production of succinate is 62.5 g/L in 3 L fermenter and the conversion rate of glycerol to SA was 64.2%...