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.

The present invention is in the technical field of synthetic biology and metabolic engineering. More particularly, the present invention is in the technical field of metabolically engineered cells and use of said cells in a cultivation, preferably fermentation. The present invention describes a metabolically engineered cell and a method by cultivation, preferably fermentation, with said cell for production of a bioproduct. More specifically, the present invention describes a metabolically engineered cell and a method by cultivation, preferably fermentation, with said cell for production of an N-acetylneuraminic acid (Neu(n)Ac)-containing compound, wherein (n) is 4, 5, 7, 8 or 9 or a combination thereof. The metabolically engineered cell comprises a pathway for production of said Neu(n)Ac-containing compound and is modified in the expression or activity of at least one NeuNAc synthase according to the present invention. Furthermore, the present invention provides for purification of said Neu(n)Ac-containing compound from the cultivation.

The disclosure is in the technical field of synthetic biology and metabolic engineering. More particularly, the disclosure is in the technical field of metabolically engineered cells and use of the cells in a cultivation or fermentation. The disclosure describes a cell and a method for production of a di- and/or oligosaccharide. The cell comprises a pathway for production of the di- and/or oligosaccharide and is genetically modified for expression and/or overexpression of at least one set of multiple coding DNA sequences wherein the multiple coding DNA sequences within one set differ in nucleotide sequence and each encode a polypeptide, wherein the polypeptides have the same function and/or activity of interest. Furthermore, the disclosure provides for purification of the di- and/or oligosaccharide from the cultivation.

Mammalian milk oligosaccharides (MMO) are produced in plants engineered to express recombinant MMO biosynthetic pathways.

This disclosure is in the technical field of synthetic biology and metabolic engineering. More particularly, the disclosure is in the technical field of fermentation of metabolically engineered microorganisms. The disclosure describes engineered microorganisms able to synthesize sialylated compounds via an intracellular biosynthesis route. These microorganisms can dephosphorylate N-acetylglucosamine-6-phopshate to N-acetyl glucosamine and convert the N-acetylglucosamine to N-acetylmannosamine. These microorganisms also have the ability to convert N-acetylmannosamine to N-acetyl-neuraminate. Furthermore, provided is a method for the large scale in vivo synthesis of sialylated compounds, by culturing a microorganism in a culture medium, optionally comprising an exogenous precursor such as, but not limited to lactose, lactoNbiose, N-acetyllactosamine and/or an aglycon, wherein the microorganism intracellularly dephosphorylates N-acetylglucosamine-6-phopshate to N-acetylglucosamine, converts N-acetylglucosamine to N-acetylmannosamine and convert the latter further to N-acetyl-neuraminate.