Structural studies of the polysaccharides from the lipopolysaccharides of Azospirillum brasilense Sp246 and SpBr14

•Lipopolysaccharides of A. brasilense Sp246 and SpBr14 were degraded with mild acid.•The O-specific polysaccharides (OPS) were obtained.•Structure of the repeating units of the OPS was established by 2D NMR spectroscopy.•The OPS of both strains contained the same two distinct repeating units.

Lipopolysaccharides from closely related Azospirillum brasilense strains, Sp246 and SpBr14, were obtained by phenol–water extraction. Mild acid hydrolysis of the lipopolysaccharides followed by GPC on Sephadex G-50 resulted in polysaccharide mixtures. On the basis of sugar and methylation analyses, Smith degradation and 1H and 13C NMR spectroscopy data, it was concluded that both bacteria possess the same two distinct polysaccharides having structures 1 and 2:Figure optionsDownload full-size imageDownload as PowerPoint slideStructure 1 has been reported earlier for a polysaccharide of A. brasilense 54 [Fedonenko et al., 2011]6 whereas to our knowledge structure 2 has not been hitherto found in bacterial polysaccharides.

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