The structural characterization of the O-polysaccharide antigen of the lipopolysaccharide of Escherichia coli serotype O118 and its relation to the O-antigens of Escherichia coli O151 and Salmonella enterica O47 Original Research Article

Mild acid hydrolysis of the lipopolysaccharide produced by Escherichia coli O118:H16 standard strain (NRCC 6613) afforded an O-polysaccharide (O-PS) composed of d-galactose, 2-acetamidoylamino-2,6-dideoxy-l-galactose , 2-acetamido-2-deoxy-d-glucose, ribitol, and phosphate (1:1:1:1:1). From DOC-PAGE, sugar and methylation analyses, one- and two-dimensional NMR spectroscopy, capillary electrophoresis-mass spectrometry, hydrolysis, and sequential Smith-type periodate oxidation studies, the O-PS was determined to be an unbranched linear polymer having the structure: [6)-α-d-Galp-(1→3)-α-l-FucpNAm-(1→3)-β-d-GlcpNAc-(1→3)-Rib-ol-5-P-(O→]n The structure of the O-PS is consistent with the reported DNA data on the O-antigen gene-cluster of E. coli O118 and interestingly, the O-PS is similar to the structures of the O-antigens of Salmonella enterica O47 and E. coli O151:H10 reference strain 880-67, as predicted from the results of DNA sequencing of their respective O-antigen gene-clusters.