重组大肠杆菌全细胞转化马来酸高效合成富马酸

重组Escherichia coli细胞催化马来酸合成富马酸时，细胞中富马酸酶将产物富马酸转化成苹果酸，转化率达15.5%，降低了富马酸的转化率和纯度。将E. coli BL21（DE3）基因组中fumA-fumC基因敲除，并高效表达马来酸顺反异构酶，重组菌BL21（DE3）△fumA-fumC/pET24a-maiA经发酵罐培养，可产生64 g/L菌体，马来酸顺反异构酶表达量达306 U/mL。按照60 g/L的发酵液：2 mol/L富马酸为1∶4的体积比配置反应液，37 ℃反应1 h，富马酸转化率高达98.4%，仅产生0.7%的苹果酸副产物。该结果为全细胞催化法合成富马酸的工业化奠定了基础。
Fumarate could be produced from maleate with whole cell of recombinant Escherichia coli. However，malate，with a yield of 15.5%，was generated as byproduct by the cellular fumarase，resulting in a decreased fumarate yield and purity. The chromosomal genes，fumA and fumC，in E. coli BL21（DE3） were inactivated，followed by over expression of the maleate cis-trans isomerate. After cultured in a bioreactor，the resulting strain BL21（DE3）△fumA-fumC/pET24a-maiA could generate 64 g/L dry cell weight and maleate cis-trans isomerate of 306 U/mL. With a volumetric ratio of fermentation broth（60 g/L dry cell weight）：fumarate（2 mol/L）=1∶4，fumarate yield of 98.4% and malate yield of 0.7% were produced after incubation at 37 ℃ for 1 h. These results laid a foundation for industrial production of fumarate by whole-cell biocatalyst