Structures and genetics of Kdo-containing O-antigens of Cronobacter sakazakii G2706 and G2704, the reference strains of serotypes O5 and O6 Original Research Article

Cronobacter sakazakii G2706 and G2704 are the reference strains of serotypes O5 and O6 in the serological classification of this species proposed recently. Mild acid degradation of the lipopolysaccharides of both strains resulted in cleavage of the O-polysaccharide chains at the acid-labile linkage of 3-deoxy-d-manno-oct-2-ulosonic acid (Kdo) to yield oligosaccharides representing repeating units of the O-polysaccharides. The oligosaccharides and alkali-degraded lipopolysaccharides were studied by sugar analysis along with 1D and 2D 1H and 13C NMR spectroscopy, and the following O-polysaccharide structures were established: