Abstract: A genetically engineered bacterium and a preparation method and use thereof are disclosed. The genetically engineered bacteria contain a gene encoding ?-1,2-fucosyltransferase, and a gene encoding a protein tag is connected to the gene encoding ?-1,2-fucosyltransferase; the protein tag is MBP, SUMO1, SUMO2 or TrxA, the amino acid sequence of the MBP is shown in SEQ ID NO: 2, the amino acid sequence of the SUMO1 is shown in SEQ ID NO: 3, the amino acid sequence of the SUMO2 is shown in SEQ ID NO: 4, the amino acid sequence of the TrxA is shown in SEQ ID NO: 5. Fermentation with the genetically engineered bacteria can greatly increase the yield of 2?-fucosyllactose compared to the genetically engineered bacteria that only expresses ?-1,2-fucosyltransferase exogenously, and the yield can be more than doubled in a preferred case.

Abstract: The present invention discloses a genetically engineered bacteria, which is E. coli integrated with lysogenic ?DE3, and lacZ gene is completely inactivated, but does not affect exogenous protein expression of the genetically engineered bacteria. The present invention also discloses a method for culturing the genetically engineered bacteria, and a method for preparing human milk oligosaccharides using the same, and use of the genetically engineered bacteria. The genetically engineered bacteria of the present invention can efficiently produce human milk oligosaccharides, such as 2?-fucosyllactose, and have wide industrial application prospects.

Abstract: The invention discloses a genetically engineered bacterium and a method for preparing a fucosylated oligosaccharide using the same. The method includes: transferring a fucosyl group of a donor to an oligosaccharide receptor by a fucosyltransferase heterologously expressed in a genetically engineered bacterium; wherein the donor is a nucleotide-activated donor, the fucosyltransferase has ?-1,2-fucosyltransferase activity; wherein, the fucosyltransferase is selected from one or more of the enzymes corresponding to NCBI Accession Numbers WP_109047124.1, RTL12957.1, MBP7103497.1, WP_120175093.1, RYE22506.1, WP_140393075.1 and HJB91111.1. The preparation method of the invention has high yield, greatly improved substrate conversion rate and product conversion rate, and has the potential to be applied to industrial production.

Abstract: The invention discloses a genetically engineered bacterium and its application in the preparation of sialyllactose. The genetically engineered bacterium has an N-acetylneuraminic acid biosynthesis pathway, includes multiple copies of a gene neuB for encoding sialic acid synthase, and the gene neuB is initiated for expression by a strong promoter. Using the genetically engineered bacteria of the invention to produce sialyllactose has the advantages of high yield and low overall cost.