Human milk oligosaccharides can be synthesized in large quantities using precision industrial fermentation methods e.g. by the commonly used, non-pathogenic bacteria Escherichia coli. During the fermentation process the bacteria are fed with a carbon-source (e.g. glucose), salts, minerals and trace elements under aseptic conditions in a stainless steel bioreactor, while lactose is added to the process as precursor molecule. Bacteria are then converting the lactose into human milk oligosaccharides by decorating it with other sugar monomers. After the fermentation process the HMOs are completely separated from the bacteria, proteins and DNA using different filtration techniques. Subsequently the HMOs are purified, crystallized, dried, packaged and delivered to infant formula manufacturers where they are mixed with other components of infant formula.