The Cronobacter spp. (former Enterobacter sakazakii) are Gram-negative pathogens most dangerous to infants, and cause meningitis or necrotizing enterocolitis [1].
The O-polysaccharide (OPS), also known as O-antigen, is the external region of lipopolysaccharides (LPS) found in Gram-negative bacteria. This unique structure is unique to Gram-negative bacteria and is the basis for further classification of the types and species [2]. Determination of the chemical structure of repeating unit of the O‑polysaccharide is essential for both the chemotaxonomy, and diagnostics.
The structural studies were performed on the O-polysaccharide of Cronobacter malonaticus NTU 681.
Purified polysaccharide was analyzed by NMR spectroscopy (1H, COSY, TOCSY, ROESY, HSQC, HMBC and HSQC-TOCSY experiments) and by chemical methods. The study allowed the isolation LPS and separation of OPS fractions, determine the type and number of monosaccharides units in OPS and their positions of linkages. Interpretation of NMR spectra allowed the assignment of 1H and 13C chemical shifts of OPS and revealed the sequence of the sugar residues in the repeating unit.
[1] J.M. Farber, S.J. Forsythe, Emerging issues in food safety Enterobacter sakazakii, ASM PRESS, Washington, D.C., (2008),
[2] H. Friedman, T.W. Klein, M. Nakano, A. Nowotny ed., Endotoxin, Adv. Exp. med. Biol. 256, 81-99 (1990)
