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: [Display omitted] Structure 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.