Structure of a polysaccharide from the lipopolysaccharides of Vibrio vulnificus strains CECT 5198 and S3-I2-36, which is remarkably similar to the O-polysaccharide of Pseudoalteromonas rubra ATCC 29570

High-molecular-mass polysaccharides were released by mild acid degradation of the lipopolysaccharides of two wild-type Vibrio vulnificus strain, a flagellated motile strain CECT 5198 and a non-flagellated nonmotile strain S3-I2-36. Studies by sugar analysis and partial acid hydrolysis along with H-1 and C-13 NMR spectroscopies showed that the polysaccharides from both strains have the same trisaccharide repeating unit of the following structure: -> 4)-beta-D-GlcpNAc3NAcylAN-(1 -> 4)-alpha-L-GalpNAmA-(1 -> 3)-alpha-D-QuipNAc-(1 -> where QuiNAc stands for 2-acetamido-2,6-dideoxyglucose, GalNAmA for 2-acetimidoylamino-2-deoxygalacturonic acid, GlcNAc3NAcylAN for 2-acetamido-3-acylamino-2,3-dideoxyglucuronamide and acyl for 4-D-malyl (similar to 30%) or 2-O-acetyl-4-D-malyl (similar to 70%). The structure of the polysaccharide studied resembles much that of a marine bacterium Pseudoalteromonas rubra ATCC 29570 reinvestigated in this work. The latter differs in (i) the absolute configuration of malic acid (L VS D), (ii) 3-O-acetylation of GalNAmA and (iii) replacement of QuiNAc with its 4-keto biosynthetic precursor. (C) 2009 Elsevier Ltd. All rights reserved.