The present disclosure relates to the production of mixtures of sialylated Human Milk Oligosaccharides (HMOs), in particular 3SL and 6SL and genetically modified cells and their use in said production, where the cells express a heterologous sialyltransferase with dual -2,3-sialyltransferase/-2,6-sialyltransferase activity.

Production of a mixture of neutral fucosylated oligosaccharides by a cell. The disclosure is in the technical field of synthetic biology and metabolic engineering. More particularly, the disclosure is in the technical field of cultivation or fermentation of metabolically engineered cells. The disclosure describes a cell metabolically engineered for production of a neutral mixture of at least four different neutral fucosylated oligosaccharides. Furthermore, the disclosure provides a method for the production of a neutral mixture of at least four different neutral fucosylated oligosaccharides by a cell as well as the purification of at least one of the neutral oligosaccharides from the cultivation.

Provided herein are genetically modified yeast cells capable of producing one or more human milk oligosaccharides (HMOs) and methods of making such cells. The yeast cells are engineered to comprise a heterologous nucleic acid encoding a transporter protein and one or more heterologous nucleic acids that encode enzymes of a HMO biosynthetic pathway. Also provided are fermentation compositions including the disclosed genetically modified yeast cells, and related methods of producing and recovering HMOs generated by the yeast cells.