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: Citrobacter freundii, Klebsiella pneumoniae, O-antigen, Polysaccharide structure
FEMS immunology and medical microbiology, 2008, v. 53(1), pp. 60-64
Lipopolysaccharide was extracted from cells of Citrobacter freundii PCM 1443 from serogroup O39 and degraded by mild acid hydrolysis to give an O-polysaccharide. Based on enzymatic and methylation analyses, along with 1H and 13C nuclear magnetic resonance spectroscopy, it was found that the lipopolysaccharide studied has two different linear polysaccharide chains of D-galactan type containing 3-substituted galactose residues. One of the galactans has the disaccharide repeating units of a-D-galactopyranose and b-D-galactofuranose and the other is comprised of a-D-galactopyranose and b-D-galactopyranose, the latter being substituted in 25% repeats with PEtN at O-6. An immunoblotting assay demonstrated that the lipopolysaccharide of C. freundii PCM 1443 is serologically related to that of Klebsiella pneumoniae O1, which contains the same galactan chains but is devoid of phosphoethanolamine.