Structure of the O-polysaccharide of Proteus mirabilis CCUG 10701 (OB) classified into a new Proteus serogroup, O74

An acidic O-polysaccharide was isolated by mild acid degradation of the lipopolysaccharide of Proteus mirabilis CCUG 10701 (OB) and studied by chemical analyses and 1H and 13C NMR spectroscopy. The following structure of the tetrasaccharide repeating unit of the polysaccharide was established:→3)-β-d-GlcpNAc6Ac-(1→2)-β-d-GalpA4Ac-(1→3)-α-d-GalpNAc-(1→4)-α-d-GalpA-(1→,where the degree of O-acetylation at position 6 of GlcNAc is ∼50% and at position 4 of β-GalA ∼60%. Based on the unique structure of the O-polysaccharide and serological data, it is proposed to classify P. mirabilis CCUG 10701 (OB) into a new Proteus serogroup, O74.