Structural analysis of the O-polysaccharide from the lipopolysaccharide of Azospirillum brasilense S17

A mixture of two structurally distinct neutral O-polysaccharides was obtained by mild acid degradation of the lipopolysaccharide isolated by the phenol/water extraction from the asymbiotic diazotrophic rhizobacterium Azospirillum brasilense SIT The following structures of the O-polysaccharides were established by composition and methylation analyses, Smith degradation, and H-1 and C-13 NMR spectroscopy, including a 2D NOESY experiment: [GRAPHICS] where L-Rha2Me stands for 2-O-methyl-L-rhamnose and SHb for the (S)-3-hydroxybutanoyl group. The occurrence of two distinct polysaccharides is reported for the first time in Azospirillum spp. (c) 2007 Elsevier Ltd. All rights reserved.