Structure of the O-specific polysaccharide from the lipopolysaccharide of Azospirillum brasilense KR77

Azospirillum brasilense is a plant-growth-promoting rhizobacterium widely distributed in associations with crops. Lipopolysaccharide was extracted by Westphal procedure from A. brasilense KR77, isolated in Senegal. Mild acid hydrolysis of the lipopolysaccharide followed by GPC on Sephadex G-50 resulted in O-specific polysaccharide, which was studied by compositional analysis, 1D and 2D ¹H and ¹³C NMR spectroscopy along with computational NMR-based structure analysis, and Smith degradation. The following structure of heptasaccharide repeating units was established: →2)-[α-d-Galf-(1→2)-α-l-Rhap-(1→3)-α-l-Rhap-(1→3)-α-l-Rhap(1→3)]-β-d-Glcp-(1→3)-α-l-Fucp-(1→3)-β-d-GlcpNAc-(1 → .