The expression of lipopolysaccharide by strains of Shigella dysenteriae, Shigella flexneri and Shigella boydii and their cross-reacting strains of Escherichia coli.

Strains of Shigella dysenteriae, Shigella flexneri and Shigella boydii express lipopolysaccharides, that enable the serotyping of strains based on their antigenic structures. Certain strains of S. dysenteriae, S. flexneri and S. boydii are known to share epitopes with strains of Escherichia coli; however, the lipopolysaccharide profiles of the cross-reacting organisms have not been compared by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) lipopolysaccharides profiling. In the present study, type strains of these bacteria were examined using SDS-PAGE/silver staining to compare their respective lipopolysaccharide profiles. Strains of S. dysenteriae, S. boydii and S. flexneri all expressed long-chain lipopolysaccharide, with distinct profile patterns. The majority of strains of Shigella spp., known to cross-react with strains of E. coli, had lipopolysaccharide profiles quite distinct from the respective strain of E. coli. It was concluded that while cross-reacting strains of Shigella spp. and E. coli may express shared lipopolysaccharide epitopes, their lipopolysaccharide structures are not identical.

[Antigenic polysaccharides of bacteria: 40. The structures of O-specific polysaccharides from Shigella dysenteriae types 3 and 9 and S. boydii type 4 revised by NMR spectroscopy].

The reported structures of O-specific polysaccharides from three standard strains of Shigella bacteria were corrected by modern NMR techniques. The revisions concerned the configuration of the O-glycoside linkage (S. dysenteriae type 3, structure 1), the positions of monosaccharide residue glycosylation and acetylation by pyruvic acid (S. dysenteriae type 9, structure 2), and the attachment position of the side monosaccharide chain (S. boydii type 4, structure 3) [struxture in text].

Estudio comparativo de la actividad antibacteriana in vitro de los neumatóforos de Heritiera fomes y Xylocarpus moluccensis / A comparative study on the in vitro antibacterial activity of the pneumatophores of Heritiera fomes and Xylocarpus moluccensis

Se evaluó la actividad antibacteriana in vitro de los extractos de etanol de los neumatóforos de Xylocarpus moluccensis (Familia: Meliaceae) y Heritiera fomes (Familia: Sterculiaceae) frente a diversas cepas bacterianas utilizando el ensayo de difusión en disco. Ambos extractos presentaron perfiles antibacterianos similares, y las zonas de inhibición fueron >10 mm en la mayoría de los casos. Estos extractos presentaron la máxima actividad frente a aerógenos Enterobacter, siendo las zonas de inhibición de 19 y 21 mm, respectivamente. La concentración inhibitoria mínima(CIM) se determinó mediante el método de dilución en caldo de cultivo. El extracto de X. moluccensis fue el más potente frente a Shigella boydii y Shigella sonnie (CIM = 200 y 300 mg/mL, respectivamente). Se puede asumirque X. moluccensis y H. fomes podrían ser fuentes potenciales de nuevos descubrimientos para el desarrollo de fármacos (AU)

The ethanol extracts of the pneumatophores of Xylocarpus moluccensis (Family: Meliaceae) and Heritiera fomes (Family: Sterculiaceae) were assessed for in vitro antibacterial activities against a number of bacterial strains using the disc diffusion assay. Both extracts showed similar antibacterial profiles, and the zones of inhibitions were >10 mm in the most cases. These extracts exhibited the most prominent activity against Enterobacter aerogenes, with the zones of inhibition of 19 and 21 mm, respectively. The minimum inhibitory concentration (MIC) was determined by the broth dilution method. The extract of X. moluccensis was the most potent against Shigella boydii and Shigella sonnie (MIC = 200 and 300 mg/mL, respectively). It can be assumed that that X. moluccensis and H. fomes could be potential sources for novel ‘lead’ discovery for antibacterial drug development (AU)

Spectroscopic characterization of microorganisms by Fourier transform infrared microspectroscopy.

Spectroscopic fingerprints of bacteria were investigated by Fourier transform infrared (FTIR) microspectroscopy for the elucidation of chemical composition and structural information during growth. Good differentiation of six microorganisms was achieved down to the strain level. The inherent compositional and structural differences of cell envelopes and cytoplasm were investigated and utilized to obtain more detailed analysis of the spectroscopic features. Bands or regions of key functional groups were also identified in the original spectra. Microspectroscopic monitoring of bacterial growth demonstrated that FTIR spectroscopy cannot only provide molecular fingerprints of the cell envelope, but also compositional and metabolic information of the cytoplasm under different physiological conditions. This approach could be an effective alternative to traditional nutritional and biochemical methods to monitor and assess the effects of inhibitors and other environmental factors on microbial cell growth.

Structure of the O-specific polysaccharide chain of Shigella boydii type 5 lipopolysaccharide: a repeated study.

An acidic, partially O-acetylated O-specific polysaccharide was obtained by mild acid degradation of Shigella boydii type 5 lipopolysaccharide and studied by 1H and 13C NMR spectroscopy, including 2D COSY, 13C-1H heteronuclear COSY, 1D NOE, and 2D ROESY experiments, and chemical methods (sugar and methylation analysis, O-deacetylation, carboxyl reduction, solvolysis with anhydrous HF, partial acid hydrolysis. Smith degradation). It was concluded that the polysaccharide has a hexasaccharide repeating unit of the following structure: [Formula: See Text] with the degree of O-acetylation varying over 30-50%. The established structure differs from that proposed recently for the O-specific polysaccharide of the same S. boydii serotype [M.J. Albert et al., Carbohydr. Res., 265 (1994) 121-127].

Structural studies of the Shigella boydii type 5 O-antigen polysaccharide.

The structure of the Shigella boydii type 5 O-antigen polysaccharide has been investigated by sugar and methylation analyses, and specific degradations. It is proposed that it is composed of hexasaccharide repeating units with the following structure. The repeating unit also contains an O-acetyl group, linked to one of the primary positions. [formula: see text]

Relatedness of O-specific lipopolysaccharide side chain genes from strains of Shigella boydii type 12 belonging to two clonal groups and from Escherichia coli O7:K1.

The O-specific lipopolysaccharide side chains of Escherichia coli O7 and Shigella boydii type 12 possess similar but not identical chemical structures. We investigated the genetic relatedness between the O-specific side chain genes in members of these two species. Examination of outer membrane protein and lipopolysaccharide (LPS) banding patterns demonstrated that five strains which had been identified as S. boydii type 12 fell into two clonal groups, SB1 and SB2. Hybridizations with O7-specific radiolabeled probes derived from the chromosomal DNA of an E. coli O7 strain detected identical fragments among the three SB1 strains of S. boydii type 12 and the two E. coli O7 reference isolates. The two other S. boydii type 12 strains, which belonged to the SB2 clone, did not show homologies with the O7 probe under high-stringency conditions of hybridization. The homology between the O7 and type 12 LPS gene regions from the SB1 strains was further confirmed by the construction of O-specific side chain-deficient mutations in these strains by homologous recombination of a suicide plasmid containing O7-specific DNA sequences. Immunoblot experiments with O7 antiserum gave a weak cross-reaction with LPS purified from the SB2 strains but a very strong cross-reaction with the LPS from SB1 isolates. Antiserum raised to one of the SB2 strains cross-reacted only with S. boydii type 12 LPS from the SB1 clone but failed to react with O7 LPS.