| abstract |
The invention belongs to the technical field of recombinant microorganism genetic engineering, and in particular relates to a genetically engineered bacterium Z3 capable of increasing the yield of 3'-sialyllactose (3'-SL) and its application. The present invention takes the high-yielding N-acetylneuraminic acid (Neu5Ac) strain 3D6.2 as the starting strain, and integrates the exogenous gene N-acylneuraminic acid cytidyltransferase NeuA and α-2,3-sialyltransferase Nst In the genome of Bacillus subtilis, the β-galactosidase gene yesZ was knocked out, and the promoters of the key enzymes N-acylneuraminic acid cytidyltransferase NeuA and α-2,3-sialyltransferase Nst were optimized The optimal expression level was obtained, and the carbon source in the fermentation medium was also optimized to find the optimal carbon source for 3'-SL synthesis, so that the yield of 3'-SL in shake flask fermentation reached 185.2 mg/L. |