Structures of the O-polysaccharides of Salmonella enterica O59 and Escherichia coli O15

The O-polysaccharide of Salmonella enterica O59 was studied using sugar analysis and 2D 1H and 13C NMR spectroscopy, and the following structure of the tetrasaccharide repeating unit was established: →2)-β-d-Galp-(1→3)-α-d-GlcpNAc-(1→4)-α-l-Rhap-(1→3)-β-d-GlcpNAc-(1→ Accordingly, the O-antigen gene cluster of S. enterica O59 includes all genes necessary for the synthesis of this O-polysaccharide. Earlier, another structure has been reported for the O-polysaccharide of Salmonella arizonae (S. enterica IIIb) O59, which later was found to be identical to that of Citrobacter (Citrobacter braakii) O35 and, in this work, also to the O-polysaccharide of Escherichia coli O15.