Escherichia coli expression strain and method thereof for producing N-acetyl-D-neuraminic acid

The invention relates to a method for producing an N-acetyl-D-neuraminic acid based on genomes through enzymatic synthesis. The method is implemented through integrating an isomerase gene BT0453 and an aldolase gene nanA to a malE gene region so as to obtain a recombinational genetically engineered bacterium, wherein the isomerase gene BT0453 and the aldolase gene nanA are respectively placed under a T7 strong promoter, the isomerase gene BT0453 is derived from a polymorphic bacteroidetes VPI-5482 genome, and the aldolase gene nanA is derived from escherichia coli; enabling a strain to express the isomerase BT0453 and the aldolase NanA under the inducing of isopropyl-beta-D-isopropyl thiogalactoside, through taking a whole cell as a catalyst and n-acetyl-D-glucosamine and sodium pyruvate as substrates, preparing a N-acetyl-D-neuraminic acid through catalytic synthesis, wherein the yield can reach 36.3%. The efficient N-acetyl-D-neuraminic acid expression system has a potential of becoming an N-acetyl-D-neuram