The O-specific polysaccharide of the marine bacterium Rheinheimera pacifica KММ 1406T containing d- and l-2-acetamido-2-deoxy-galacturonic acids

•The new structure of the O-polysaccharide of R. pacifica KММ 1406T is reported.•The OPS contains both d and l isomers of 2-acetamido-2-deoxy-galacturonic acids.•The presence of 4-(N-acetyl-d-alanyl)amino-4,6-dideoxy-d-glucose was found in OPS. The O-specific polysaccharide was isolated from the lipopolysaccharide of Rheinheimera pacifica KММ 1406T and studied by chemical methods along with 1H and 13C NMR spectroscopy. It was shown that the polysaccharide contains one residue each of 2-acetamido-2-deoxy-d-galactose (d-GalNAc), 2-acetamido-2-deoxy-d- and 2-acetamido-2-deoxy-l-galacturonic acids (d-GalNAcA, l-GalNAcA), 2,4-diacetamido-2,4,6-trideoxy-d-glucose (d-QuiNAc4NAc), and 4-(N-acetyl-d-alanyl)amino-4,6-dideoxy-d-glucose (d-Qui4NAlaAc) and has the following structure: →4)-α-d-GalpNAc-(1→4)-α-l-GalpNAcA-(1→3)-β-d-QuipNAc4NAc-(1→2)-β-d-Quip4NDAlaAc-(1→4)-α-d-GalpNAcA-(1→