Exostructures of Rhizobium meliloti

Mutaftschiev, S

doi:10.1016/0378-1097(82)90131-8

Cited by 14 publications

(22 citation statements)

References 18 publications

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“…A drop of bacterial culture was placed on a coated grid for 1 min and blotted with filter paper. The glutaraldehyde-ruthenium red-uranyl acetate method was used to stain the cells (36). The sample was dried and observed by transmission electron microscopy.…”

Section: Methodsmentioning

confidence: 99%

NovelAeromonas hydrophilaPPD134/91 Genes Involved in O-Antigen and Capsule Biosynthesis

Zhang¹,

Arakawa

Leung

2002

Infect Immun

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The sequences of the O-antigen and capsule gene clusters of the virulent Aeromonas hydrophila strain PPD134/91 were determined. The O-antigen gene cluster is 17,296 bp long and comprises 17 genes. Seven pathway genes for the synthesis of rhamnose and mannose, six transferase genes, one O unit flippase gene, and one O-antigen chain length determinant gene were identified by amino acid sequence similarity. PCR and Southern blot analysis were performed to survey the distribution of these 17 genes among 11 A. hydrophila strains of different serotypes. A. hydrophila PPD134/91 might belong to serotype O:18, as represented by JCM3980; it contained all the same O-antigen genes as JCM3980 (97 to 100% similarity at the DNA and amino acid levels). The capsule gene cluster of A. hydrophila PPD134/91 is 17,562 bp long and includes 13 genes, which were assembled into three distinct regions similar to those of the group II capsule gene cluster of Escherichia coli and other bacteria. Regions I and III contained four and two capsule transport genes, respectively. Region II had five genes which were highly similar to capsule synthesis pathway genes found in other bacteria. Both the purified O-antigen and capsular polysaccharides increased the ability of the avirulent A. hydrophila strain PPD35/85 to survive in naïve tilapia serum. However, the purified surface polysaccharides had no inhibitory effect on the adhesion of A. hydrophila PPD134/91 to carp epithelial cells.Surface polysaccharides, such as O-antigen and capsule, are important bacterial cell surface components. The O-antigen polysaccharide is covalently ligated to the lipid A-core complex and extends outward from the cell surface. The capsule is an extracellular polysaccharide enclosing the bacterium while remaining attached to the cell. Both the O-antigen polysaccharide and the capsule are composed of repeating oligosaccharide units (44). They act as prominent antigens and play important roles in the pathogenicity of many bacterial pathogens, such as protecting bacterial cells from complement-mediated serum killing (20, 30), acting as adhesion factors (31), protecting the bacteria from the effects of desiccation (38), and aiding survival in phagocytes (56). The serogrouping of bacterial strains within a genus is determined by the structural variability of surface polysaccharides. For example, Escherichia coli strains are divided into more than 160 serogroups based on the different surface polysaccharides (67). Klebsiella species have been classified into 72 serogroups based on the structural variability of their capsular polysaccharides (39).Aeromonas hydrophila is an important pathogen of a wide variety of aquatic and terrestrial animals, especially fish (4). In fish, it causes hemorrhagic septicemia, which often results in high mortalities in commercial aquaculture. Some strains of A. hydrophila are also reported to cause infections in humans. The clinical symptoms include septicemia (17), meningitis (25), peritonitis (35), pneumonia (32), myonecrosis (34), and diarrh...

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Section: Methodsmentioning

confidence: 99%

NovelAeromonas hydrophilaPPD134/91 Genes Involved in O-Antigen and Capsule Biosynthesis

Zhang¹,

Arakawa

Leung

2002

Infect Immun

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“…The morphology of extracellular polysaccharides in interconnected fibrils has been widely discussed in the literature as being, or not being, an artefact of SEM preparation (Fraser and Gilmore 1986, Mutafschiev et a/. 1982, Read et al 1983, Rhodes et al 1985, Van Doorn et al 1990).…”

Section: Discussionmentioning

confidence: 99%

Cryoscanning electron microscopy of microbial extracellular polysaccharides and their association with minerals

Chenu

Jaunet

1992

Scanning

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The morphology of pure microbial extracellular polysaccharides (EPS) and of their association with a mineral was studied by scanning electron microscopy. Several methods were compared: cryo‐SEM, critical point dehydration (CPD), and TEM observation after solvent exchanges and inclusion in a resin. The EPS were observed as fibrils, interconnected into a network. Their dimensions were compared with literature data on the conformation and shape of the given EPS. It was deduced that these EPS have an undoubtably fibrillar structure when hydrated, and that some aggregation or collapse artifacts took place in both CPD or cryo‐SEM samples but were quite limited. Cryo‐SEM appears then as a relevant tool for the study of the secretion of EPS by microorganisms in soils.

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“…The glutaraldehyde/ruthenium red/uranyl acetate method was used to stain the A. hydrophila cells (Mustaftschiev et al, 1982). A drop of bacterial culture was placed on a carbon-coated grid and surplus fluid was removed with filter paper.…”

Section: Methodsmentioning

confidence: 99%

Detection and genetic analysis of group II capsules in Aeromonas hydrophila

et al. 2003

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The genetic organization and sequences of the group II capsule gene cluster of Aeromonas hydrophila PPD134/91 have been determined previously. The purified capsular polysaccharides can increase the ability of avirulent strain PPD35/85 to survive in naive tilapia serum but have no inhibitory effect on the adhesion of PPD134/91 to carp epithelial cells. In this study, the presence of group II capsules among 33 randomly chosen A. hydrophila strains was examined by electron microscopy and genetic analysis. Ten strains were found to produce group II capsules. A PCR detection system was developed to identify two types of group II capsules (IIA and IIB) based on their genetic organization in the region II gene clusters. Group IIA capsules in the authors' collection of A. hydrophila strains are mainly found in the O : 18 and O : 34 serogroups, while group IIB capsules are found in the O : 21 and O : 27 serogroups. The presence of group II capsules in A. hydrophila strongly correlates with the serum and phagocyte survival abilities (seven out of ten strains). The results indicate that the authors' PCR detection system can constitute a reliable assay for the classification of group II capsules in A. hydrophila.

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Exostructures of Rhizobium meliloti

Cited by 14 publications

References 18 publications

NovelAeromonas hydrophilaPPD134/91 Genes Involved in O-Antigen and Capsule Biosynthesis

NovelAeromonas hydrophilaPPD134/91 Genes Involved in O-Antigen and Capsule Biosynthesis

Cryoscanning electron microscopy of microbial extracellular polysaccharides and their association with minerals

Detection and genetic analysis of group II capsules in Aeromonas hydrophila

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