Improvement of 1,3-Butanediol Production by Engineered Escherichia coli
1,3-butanediol is an important diol used in chemical synthesis,food and medicine,daily chemical production,and more.In this study,Escherichia coli BL21(DE3)was used as the host bacterium.The 1,3-butanediol metabolic synthesis pathway was constructed using acetyl-CoA acetyltransferase PhaA,NAD(P)H-dependent acetyl-CoA reductase PhaB1 and butaldehyde dehydrogenase Bld.On this basis,the effects of aldehyde-ketone reductase PA1127 and NAD kinase were explored.The effects of NADK on the metabolic production of 1,3-butanediol in recombinant strains were studied,and the culture conditions of 1,3-butanediol producing recombinant strains were optimized in order to improve the production of 1,3-butanediol in the recombinant strains.The recombinant plasmid was constructed in the form of multi-plasmid co-transformation system and multi-cis-trans subsystem,and the recombinant strain was obtained by transformation.After the conversion experiment or fermentation,glucose consumption was determined by the DNS method,bacterial volume and NADPH levels were compared by light absorption value,and 1,3-butanediol and by-products were quantitatively analyzed by GC and HPLC.The 1,3-butanediol metabolic synthesis pathway consisting of PhaA,PhaB1 and Bld was successfully constructed,and the conversion of glucose to 1,3-butanediol was realized.Overexpression of NADK improved the ability of recombinant strains to synthesize 1,3-butanediol,but increased the yield of acetic acid,lactic acid,ethanol and other by-products.By optimizing culture conditions and medium components during fermentation,the yield of 1,3-butanediol was increased to 0.531 g/L.This conclusion provides a theoretical basis for the study of 1,3-butanediol biosynthesis.