Structure of the O-polysaccharide from the moderately halophilic bacterium Halomonas fontilapidosi KR26

Lipopolysaccharide was obtained from the aerobic moderately halophilic bacterium Halomonas fontilapidosi KR26. The O-polysaccharide was isolated by mild acid degradation of the lipopolysaccharide and was examined by chemical methods and by 1H and 13C NMR spectroscopy, including 1H,1H COSY, TOCSY, ROESY, and 1H,13C HSQC, and HMBC experiments. The following structure of the linear tetrasaccharide repeating unit was deduced. →2)-α-l-Rhap-(1→2)-α-l-Rhap-(1→3)-α-l-Rhap-(1→3)-β-d-Galp-(1→ [Display omitted] •Halomonas fontilapidosi KR26 is a moderately halophilic bacterium.•OPS was isolated from Halomonas fontilapidosi KR26 lipopolysaccharide.•The novel OPS tetrasaccharide repeating unit structure has been established.•The O-chain contains a widespread motif composed of three l-Rha residues.