aL. Hirszfeld Institute of Immunology and Experimental Therapy, Polish Academy of Sciences, Weigla, Wroclaw, Poland
bN. D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, Moscow, Russia
KEYWORDS: Lipopolysaccharide, Citrobacter, O-Specific polysaccharide structure, Endotoxin, Serological classification
FEMS immunology and medical microbiology, 2009, v. 344(13), pp. 1724-1728
The lipopolysaccharide of Citrobacter freundii O22 (strain PCM 1555) was degraded under mild acidic conditions and the O-polysaccharide released was isolated by gel chromatography. Sugar and methylation analyses along with 1H- and 13C-NMR spectroscopy, including two-dimensional 1H,1H ROESY and 1H,13C HMBC experiments, showed that the repeating unit of the O-polysaccharide has the following structure:
a-Abep(1 | 3 ->2)-a-D-Manp-(1->4)-a-L-Rhap-(1->3)-a-D-Galp-(1->
where Abe is abequose (3,6-dideoxy-D-xylo-hexose). SDS-PAGE and immunoblotting revealed that the O-antigen of C. freundii O22 is serologically identical to those of Salmonella group B serovars (Typhimurium, Brandenburg, Sandiego, Paratyphi B) but not related to other abequose-containing O-antigens tested (Citrobacter werkmanii O38 and Salmonella Kentucky) or colitose (L enantiomer of abequose)-containing O-antigen of Escherichia coli O111.