Neu5Ac used to be purified from animal sources such as edible bird's nest (Martin et al., 1977) or egg yolk (Koketsu et al., 1992). However the low sialic acid content of these materials resulted in a low overall production yield and precluded the development of an economically practical industrial process. Glycosidically bound, but not free, dietary sialic acids are used for the biosynthesis of new glycoconjugates in humans, making the quantitation of these two forms in infant food sources important, as in neonates the demand for sialic acid may exceed the de novo biosynthetic supply. Alternatively, selectable markers may encode proteins that complement auxotrophic deficiencies or supply critical nutrients not available from complex media, e.g If you liked this write-up and you would certainly like to obtain additional info concerning sialic acid manufacturer kindly visit the internet site. .