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The Pantoea agglomerans 8488 lipopolysaccharide (LPS) was isolated, purified and characterized by monosaccharide and fatty acid analysis. The O-polysaccharide and lipid A components of the LPS were separated by mild acid degradation. Lipid A was studied by electrospray ionization mass spectrometry (ESI-MS) and found to consist of hexa-, penta-, tetra- and tri-acylated species. Two-dimensional nuclear magnetic resonance (NMR) spectroscopy revealed the following structure of the O-polysaccharide repeating unit →3)-α-L-Rhap-(1→6)-α-D-Manp-(1→3)-α-L-Fucp-(1→3)-β-D-GlcNAcp-(1→. The LPS showed a low level of toxicity, was not pyrogenic, and reduced the adhesiveness index of microorganisms to 2.12, which was twofold less than the control. LPS modified by complex compounds of germanium (IV) and tin (IV) were obtained. It was found that six LPS samples modified by Sn compounds and two LPS samples modified by Ge compounds lost their toxic activity when administered to mice in a dose of LD50 (105 µg/mice or 5 mg/kg). However, none of the modified LPS samples changed their serological activity in an Ouchterlony double immunodiffusion test in agar.

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this review analyzed literature data, as well as our own research on lipopolysaccharides (lPs) of gram-negative bacteria, focusing mainly on Pantoea agglomerans, a member of the enterobacteriaceae family. the unique structures of O-specific polysaccharide chains of lPs from Pantoea agglomerans represented by both linear and branched tetra-and pentasaccharide repeating units were described for the first time. the heterogeneity of the lPs molecule itself and the presence of several lPs in the bacterial cell, which differ in the structure of lipids a, O-specific polysaccharide chains, serological activity, as well as endotoxic properties, such as toxicity and pyrogenicity, were shown. such heterogeneity represents one of the mechanisms of lPs multifunctionality. Based on the antigenicity of lPs, serotyping of P. agglomerans strains and their assignment to 10 serogroups were carried out for the first time. the high immunomodulatory activity of P. agglomerans lPs suggests the possibility to use their oligosaccharide fragments in the development of conjugated vaccines against diseases caused by gram-negative bacteria.