Structures of two O-polysaccharides of the lipopolysaccharide of Citrobacter youngae PCM 1538 (serogroup O9)

Polysaccharide chain I: → 2)-α- d-Rha p4NAc-(1 → Polysaccharide chain II: → 3)-α- d-Rha p4NAc-(1 → 3)-β- d-Rha p4NAc-(1 → Mild acid degradation of the lipopolysaccharide of Citrobacter youngae O9, strain PCM 1538 released a homopolysaccharide of 4-acetamido-4,6-dideoxy- d-mannose ( d-Rha4NAc, N-acetyl- d-perosamine). Studies by methylation analysis and 1H and 13C NMR spectroscopy, using two-dimensional 1H, 1H COSY, TOCSY, NOESY and H-detected 1H, 13C HSQC experiments showed the presence of two structurally different polysaccharides consisting of the following units: →2) -α- d -Rhap4 NAc-(1→ and→3) -α- d -Rhap4 NAc-(1→3) -β- d -Rhap4 NAc-(1→