The structure of the O-specific polysaccharide of the lipopolysaccharide from Pantoea agglomerans strain FL1

D-Rhamnan and Pyruvate-Containing Teichuronic Acid from the Cell Wall of Rathayibacter sp. VKM Ac-2759

Rathayibacter sp. VKM Ac-2759 (family Microbacteriaceae, class Actinobacteria) contains two glycopolymers in the cell wall. The main chain of rhamnan, glycopolymer 1, is built from the repeating tetrasaccharide units carrying terminal arabinofuranose residues at the non-reducing end, →3)-α-[α-D-Araf-(1→2)]-D-Rhap-(1→2)-α-D-Rhap-(1→3)-α-D-Rhap-(1→2)-α-D-Rhap-(1→. Similar to other described Rathayibacter species, rhamnose in the neutral glycopolymer of the VKM Ac-2759 strain is present in the D-configuration. Acetalated with pyruvic acid teichuronic acid, glycopolymer 2, is composed of the repeating tetrasaccharide units, →4)-β-D-GlcpA-(1→4)-β-D-Galp-(1→4)-β-D-Glcp-(1→3)-β-[4,6-S-Pyr]-D-Manp-(1→. Glycopolymers 1 and 2 were identified in prokaryotic microorganisms for the first time and their structures were established by chemical analysis and NMR spectroscopy. The obtained data can be used in taxonomic research, as well as for elucidating the mechanisms of plant colonization and infection by bacteria of the Rathayibacter genus.

Structure of O-Polysaccharide and Lipid A of Pantoea Agglomerans 8488

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.

Pantoea agglomerans P1a lipopolysaccharide: Structure of the O-specific polysaccharide and lipid A and biological activity

O-specific polysaccharide and lipid A were obtained from the lipopolysaccharide from new strain of Рantoea agglomerans P1a by mild acid hydrolysis. It was found that the major form of lipid A presented by tetraacylated derivative containing biphosphorylated GlcN disaccharide, three 14:0 (3-OH) and 12:0 residues. The structure of the O-specific polysaccharide was established by chemical, NMR and computational methods: →3)-α-D-Manp-(1 → 4)-β-D-Fucp-(1 → 4)-ɑ-D-Fucp-(1→The LPS of Р. agglomerans P1a showed low level of toxicity and pyrogenicity to compare with LPS of E. coli O55:B5 and pyrogenal (respectively).

Lipopolysaccharides of Pantoea agglomerans 7604 and 8674 with structurally related O-polysaccharide chains: Chemical identification and biological properties

Structurally related O-specific polysaccharide (O-antigen) and lipid A components were obtained by mild acid degradation of the lipopolysaccharides (LPSs) of two strains of bacteria Pantoea agglomerans, 7604 and 8674. Studies by sugar analysis along with 1D and 2D ¹H and ¹³C NMR spectroscopy enabled elucidation of the following structures of the O-polysaccharides, which differ only in the linkage configuration of a side-chain glucose residue: R=α-d-Glcp in strain 7604 or β-d-Glcp in strain 8674 Lipid A samples were studied by GC-MS and high-resolution ESI-MS and found to be represented by penta- and tetra-acyl species; lipid A of strain 8674 also included hexaacyl species. A peculiar feature of lipid A of both strains is the presence of the major cis-9-hexadecenoic (palmitoleic) acid, which has not been found in P. agglomerans strains studied earlier. The LPSs of both strains were pyrogenic, reduced the average adhesion and the index of adhesiveness and showed a relatively low level of lethal toxicity. O-antiserum against strain 7604 showed one-way cross-reactivity with the LPS of strain 8674, and O-antisera against both strains cross-reacted with LPSs of some other Р. agglomerans strains but more strains were serologically unrelated. These structural and serological data indicate immunochemical heterogeneity of Р. agglomerans strains and will find demand in classification of Р. agglomerans by O-antigens.

Studies on the O-specific polysaccharide of the lipopolysaccharide from the Pseudomonas mediterranea strain C5P1rad1, a bacterium pathogenic of tomato and chrysanthemum

An O-specific polysaccharide (OPS) was isolated from the lipopolysaccharide of Pseudomonas mediterranea strain C5P1rad1, the causal agents of tomato pith necrosis and Chrysanthemum stem rot, and studied by one- and two-dimensional ¹H and ¹³C NMR spectroscopy. The following structure of the trisaccharide repeating unit of the OPS was established, which, to our knowledge, is unique among the known bacterial polysaccharide structures: →4)-β-d-ManpNAc3NAcA-(1 → 4)-β-d-ManpNAc3NAcA-(1 → 3)-α-d-QuipNAc4NAc-(1→ where QuiNAc4NAc and ManNAc3NAcA indicate 2,4-diacetamido-2,4,6-trideoxyglucose and 2,3-diacetamido-2,3-dideoxymannuronic acid, respectively. Pre-treatment of leaves with LPS or OPS preparations at 250 and 50 μg mL^-1 did not inhibit development of a hypersensitivity reaction induced by P. mediterranea C5P1rad1 on tobacco, tomato and chrysanthemum plants. The same preparations at 250 μg mL^-1 partially prevented elicitation of the hypersensitivity reaction by Pseudomonas syringae KVPT7RC on chrysanthemum but not tobacco and tomato.

Characterization of the O-antigen polysaccharide derived from Pantoea agglomerans IG1 lipopolysaccharide

A polysaccharide fraction was isolated from the Pantoea agglomerans IG1 lipopolysaccharide (IP-PA1), and its O-antigenic polysaccharide was characterized by chemical analyses and 1D and 2D ¹H and ¹³C NMR spectroscopy. The polysaccharide is composed of linear tetrasaccharide repeating units, consisting of glucose and rhamnose, where 40% of one of the rhamnose residues is substituted with glucose: →2)-α-l-Rhap-(1→6)-α-d-Glcp-(1→2)-[β-d-Glcp-(1→3)]_0.4-α-l-Rhap-(1→2)-α-l-Rhap-(1→.

Lipopolysaccharide of Pantoea agglomerans 7969: Chemical identification, function and biological activity

Lipopolysaccharide (LPS) of Pantoea agglomerans 7969 isolated from apple tree was purified and characterized chemically by sugar and fatty acid analysis. Lipid A was analysed by negative-ion mode ESI MS and found to consist mainly of hexa- and tetra-acyl species typical of E. coli lipid A. The O-specific polysaccharide of the LPS was studied by sugar analysis, Smith degradation, and one- and two-dimensional ¹H and ¹³C NMR spectroscopy. The polysaccharide is built up of linear tetrasaccharide repeating units, and about ∼25% repeats contain glycerol 1-phosphate on the GlcNAc residue: →3)-α-l-Rha p-(1→6)-α-d-Man p-(1→3)-α-d-Fuc p-(1→3)-β-d-Glc pNAc-(1→∼25% Gro-1-P-(O→6)^⌋ The LPS showed low levels of toxic and pyrogenic activities and reduced the average adhesion and the index of adhesiveness.

A novel rhamno-mannan exopolysaccharide isolated from biofilms of Burkholderia multivorans C1576

Burkholderia multivorans C1576 is a Gram negative opportunistic pathogen causing serious lung infection in cystic fibrosis patients. Considering that bacteria naturally form biofilms, and exopolysaccharides are recognized as important factors for biofilm architecture set-up, B. multivorans was grown both in biofilm and in non-biofilm mode on two different media in order to compare the exopolysaccharides biosynthesized in these different experimental conditions. The exopolysaccharides produced were purified and their structure was determined resorting mainly to NMR spectroscopy, ESI mass spectrometry and gas chromatography coupled to mass spectrometry. The experimental data showed that both in biofilm and non-biofilm mode B. multivorans C1576 produced a novel exopolysaccharide having the following structure: [Formula: see text]. About 50% of the 2-linked rhamnose residues are substituted on C-3 with a methyl ether group. The high percentage of deoxysugar Rha units, coupled with OMe substitutions, suggest a possible role for polymer domains with marked hydrophobic characteristics able to create exopolysaccharide junction zones favouring the stability of the biofilm matrix.

Bacteriophage-resistant Staphylococcus aureus mutant confers broad immunity against staphylococcal infection in mice

In the presence of a bacteriophage (a bacteria-attacking virus) resistance is clearly beneficial to the bacteria. As expected in such conditions, resistant bacteria emerge rapidly. However, in the absence of the phage, resistant bacteria often display reduced fitness, compared to their sensitive counterparts. The present study explored the fitness cost associated with phage-resistance as an opportunity to isolate an attenuated strain of S. aureus. The phage-resistant strain A172 was isolated from the phage-sensitive strain A170 in the presence of the M^Sa phage. Acquisition of phage-resistance altered several properties of A172, causing reduced growth rate, under-expression of numerous genes and production of capsular polysaccharide. In vivo, A172 modulated the transcription of the TNF-α, IFN-γ and Il-1β genes and, given intramuscularly, protected mice from a lethal dose of A170 (18/20). The heat-killed vaccine also afforded protection from heterologous methicillin-resistant S. aureus (MRSA) (8/10 mice) or vancomycin-intermediate S. aureus (VISA) (9/10 mice). The same vaccine was also effective when administered as an aerosol. Anti-A172 mouse antibodies, in the dose of 10 µl/mouse, protected the animals (10/10, in two independent experiments) from a lethal dose of A170. Consisting predominantly of the sugars glucose and galactose, the capsular polysaccharide of A172, given in the dose of 25 µg/mouse, also protected the mice (20/20) from a lethal dose of A170. The above results demonstrate that selection for phage-resistance can facilitate bacterial vaccine preparation.