Structural studies of the O-specific polysaccharide(s) from the lipopolysaccharide of Azospirillum brasilense type strain Sp7

Elucidation of a masked repeating structure of the O-specific polysaccharide of the halotolerant soil bacteria Azospirillum halopraeferens Au4

“…Plant-associated bacteria are no exception, and the presence of non-stoichiometric substituents in the OPS has been reported for phytopathogens Pseudomonas syringae [ 29 ] and Xanthomonas campestris [ 30 ] as well as for beneficial rhizobacteria, including free-living Azospirillum spp. [ 31 – 35 ] and root-nodulating Rhizobium spp. [ 24 ].…”

“…GLC of the alditol acetates [ 37 ] and 2-octyl glycosides [ 38 ] and GLC–MS of the partially alkylated alditol acetates [ 39 ] were performed using an Agilent 7820A GC system and an Agilent MSD 5975C instrument equipped with an HP-5ms column, respectively. GLC parameters were set and chemical modifications of the OPS into the corresponding derivatives were performed as described [ 35 ]. NMR spectra were obtained using an Avance II 600 MHz instrument (Bruker, Germany) at 30 °C in 99.95 % D 2 O using sodium 3-trimethylsilylpropanoate-2,2,3,3- d 4 (δ H 0.0, δ C −1.6) as internal standard for calibration.…”

“…Selective cleavages. Periodate oxidation of an OPS sample (50 mg) was performed as described [ 35 ]. The oxidized polysaccharide was hydrolysed with 2% AcOH at 100 °C for 2 h, reduced with NaBH 4 , desalted with an Amberlit IR-120 (H + -form) resin and fractionated by exclusion chromatography on TSK HW-40 (S) in 1% AcOH to yield a mixture of oligosaccharide (OS) 1 and OS 2 (7 mg) and a higher molecular mass material.…”

Lipopolysaccharides in diazotrophic bacteria

“…Recent findings on the structure of o-antigen from strain SR80 of A. brasilense have shown that two distinct oligosaccharide repeating units are found, a trisaccharide containing D-Rha, L-Fuc, and D-Xyl (1:1:1 molar ratio respectively), and a tetrasaccharide containing D-GalNAc, L-Fuc and D-Gal (1:1:2) (Sigida et al, 2013a). Structural variations for the LPS of other strains of A. brasilense include the presence of 3-O-methyl-D-rhamnose units (strain Jm6B2) (Boyko et al, 2012) and 2-O-methyl-D-rhamnose (Strain Sp7) (Sigida et al, 2013b). The importance of LPS in the Azospirillum -plant association has been reported (Skvortsov and Ignatov, 1998; Bashan et al, 2004), but the actual role of LPS in molecular communication is yet to be understood.…”

Convergent synthesis of a tetrasaccharide repeating unit of the O-specific polysaccharide from the cell wall lipopolysaccharide of Azospirillum brasilense strain Sp7

“…There are only a limited number of reports on structural studies of the LPS present in the cell wall of Azospirilla species despite their well-known role in interactions between plants and bacteria [16–21]. Recently, Sigida et al reported the structure of the repeating unit of the LPS present in the cell wall of Azospirillum brasilense strain Sp7: a tetrasaccharide consisting of D-galactose, D-glucosamine, L-rhamnose and L-fucose [22]. …”