RESUMEN
Two polysaccharides were obtained by mild acid degradation of the lipopolysaccharide of associative nitrogen-fixing bacteria Azospirillum brasilense Jm125A2 isolated from the rhizosphere of a pearl millet. The following structures of the polysaccharides were established by sugar and methylation analyses, Smith degradation, and (1)H and (13)C NMR spectroscopy: [Formula: see text] Structure 1 has been reported earlier for a polysaccharide from A. brasilense S17 (Fedonenko YP, Konnova ON, Zdorovenko EL, Konnova SA, Zatonsky GV, Shaskov AS, Ignatov VV, Knirel YA. Carbohydr Res 2008;343:810-6), whereas to our knowledge structure 2 has not been hitherto found in bacterial polysaccharides.
Asunto(s)
Azospirillum brasilense/química , Antígenos O/química , Secuencia de Carbohidratos , Datos de Secuencia MolecularRESUMEN
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 (1)H and (13)C NMR spectroscopy data, it was concluded that both bacteria possess the same two distinct polysaccharides having structures 1 and 2: [structure: see text]. Structure 1 has been reported earlier for a polysaccharide of A. brasilense 54 [Fedonenko et al., 2011] whereas to our knowledge structure 2 has not been hitherto found in bacterial polysaccharides.
Asunto(s)
Azospirillum brasilense/química , Antígenos O/química , Secuencia de Carbohidratos , Espectroscopía de Resonancia Magnética , Datos de Secuencia MolecularRESUMEN
Lipopolysaccharide was obtained by phenol-water extraction from dried bacterial cells of Azospirillum brasilense type strain Sp7. Mild acid hydrolysis of the lipopolysaccharide followed by GPC on Sephadex G-50 resulted in a polysaccharide mixture, which was studied by composition and methylation analyses, Smith degradation and (1)H and (13)C NMR spectroscopy. The following polysaccharide structures were established, where italics indicate a non-stoichiometric (â¼40%) 2-O-methylation of l-rhamnose.
Asunto(s)
Azospirillum brasilense/química , Antígenos O/química , Azospirillum brasilense/clasificación , Secuencia de Carbohidratos , Datos de Secuencia Molecular , Antígenos O/aislamiento & purificaciónRESUMEN
A high-molecular mass polysaccharide fraction was obtained by mild acid hydrolysis of the lipopolysaccharide of diazotrophic rhizobacterium Azospirillum brasilense SR80 followed by GPC on Sephadex G-50 Superfine. Studies by composition and methylation analyses, Smith degradation, and 1D and 2D (1)H and (13)C NMR spectroscopy demonstrated the presence of two structurally distinct repeating units having the following structures: It seems likely, although not proved, that these are repeats of two distinct polysaccharides rather than they build blocks within the same polysaccharide chain. The former structure is new, whereas the latter is closely related to the O-polysaccharide structure of A. brasilense Jm6B2 established earlier, which differs in partial (~60%) 3-O-methylation of d-rhamnose only [Boiko, A. S.; Dmitrenok, A. S.; Fedonenko, Yu. P.; Zdorovenko, E. L.; Konnova, S. A.; Knirel, Y. A.; Ignatov, V. V. Carbohydr. Res.2012, 355, 92-95].
Asunto(s)
Azospirillum brasilense/química , Lipopolisacáridos/química , Antígenos O/química , Ramnosa/química , Secuencia de Carbohidratos , Hidrólisis , Espectroscopía de Resonancia Magnética , Metilación , Datos de Secuencia MolecularRESUMEN
Two types of neutral O-polysaccharides were obtained by mild acid degradation of the lipopolysaccharide isolated by phenol-water extraction from the asymbiotic diazotrophic rhizobacterium Azospirillum brasilense Jm6B2. The following structure of the major O-polysaccharide was established by composition and methylation (ethylation) analyses, Smith degradation, and 1D and 2D (1)H and (13)C NMR spectroscopy: [structure: see text] where a non-stoichiometric (~60%) 3-O-methylation of D-rhamnose is indicated by italics.
Asunto(s)
Azospirillum brasilense/química , Lipopolisacáridos/química , Manosa/análogos & derivados , Azospirillum brasilense/crecimiento & desarrollo , Conformación de Carbohidratos , Hidrólisis , Lipopolisacáridos/aislamiento & purificación , Manosa/químicaRESUMEN
Azospirillum brasilense SR55, isolated from the rhizosphere of Triticum durum, was classified as serogroup II on the basis of serological tests. Such serogroup affiliation is uncharacteristic of wheat-associated Azospirillum species. The lipid A of A. brasilense SR55 lipopolysaccharide contained 3-hydroxytetradecanoic, 3-hydroxyhexadecanoic, hexadecanoic and octadecenoic fatty acids. The structure of the lipopolysaccharide's O polysaccharide was established, with the branched octasaccharide repeating unit being represented by l-rhamnose, l-3-O-Me-rhamnose, d-galactose and d-glucuronic acid. The SR55 lipopolysaccharide induced deformations of wheat root hairs. The lipopolysaccharide was not involved in bacterial cell aggregation, but its use to pretreat wheat roots was conducive to cell adsorption. This study shows that Azospirillum bacteria can utilise their own lipopolysaccharide as a carbon source, which may give them an advantage in competitive natural environments.
Asunto(s)
Azospirillum brasilense/química , Azospirillum brasilense/crecimiento & desarrollo , Lipopolisacáridos/química , Lipopolisacáridos/metabolismo , Triticum/microbiología , Azospirillum brasilense/clasificación , Azospirillum brasilense/aislamiento & purificación , Lipopolisacáridos/inmunología , Raíces de Plantas/microbiología , SerotipificaciónRESUMEN
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 S17. The following structures of the O-polysaccharides were established by composition and methylation analyses, Smith degradation, and 1H and 13C NMR spectroscopy, including a 2D NOESY experiment: [Formula: see text] 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.
Asunto(s)
Azospirillum brasilense/química , Lipopolisacáridos/química , Secuencia de Carbohidratos , Espectroscopía de Resonancia Magnética , Datos de Secuencia MolecularRESUMEN
An O-specific polysaccharide was isolated from the lipopolysaccharide of a plant-growth-promoting bacterium Azospirillum brasilense Sp245 and studied by sugar analyses along with one- and two-dimensional 1H and 13C NMR spectroscopy, including NOESY. The polysaccharide was found to be a new rhamnan with a pentasaccharide repeating unit having the following structure:-->2)-beta-D-Rhap-(1-->3)-alpha-D-Rhap-(1-->3)-alpha-D-Rhap-(1-->2)-alpha-D-Rhap-(1-->2)-alpha-D-Rhap-(1-->