Capsulation of in vitro and in vivo Grown Bacteroides Species

Patrick, Sheila; Reid, J. H.; Coffey, A.

doi:10.1099/00221287-132-4-1099

Cited by 19 publications

(24 citation statements)

References 3 publications

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“…A large capsule (LC) and small capsule (SC) are visible by light microscopy. By electron microscopy, an encapsulating electron-dense layer (EDL) is visible adjacent to the outer membrane on bacteria non-capsulate by light microscopy (Patrick et al, 1986). Expression of the different capsular types is heritable; populations can be enriched by subculture from different interfaces of Percoll step density gradients (Patrick & Reid, 1983).…”

Section: Introductionmentioning

confidence: 99%

Multiple inverted DNA repeats of Bacteroides fragilis that control polysaccharide antigenic variation are similar to the hin region inverted repeats of Salmonella typhimurium

et al. 2003

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The important opportunistic pathogen Bacteroides fragilis is a strictly anaerobic Gram-negative bacterium and a member of the normal resident human gastrointestinal microbiota. Our earlier studies indicated that there is considerable within-strain variation in polysaccharide expression, as detected by mAb labelling. Analysis of the genome sequence has revealed multiple invertible DNA regions, designated fragilis invertible (fin) regions, seven of which are upstream of polysaccharide biosynthesis loci and are approximately 226 bp in size. Using orientation-specific PCR primers and sequence analysis with populations enriched for one antigenic type, two of these invertible regions were assigned to heteropolymeric polysaccharides with different sizes of repeating units, as determined by PAGE pattern. The implication of these findings is that inversion of the fin regions switches biosynthesis of these polysaccharides off and on. The invertible regions are bound by inverted repeats of 30 or 32 bp with striking similarity to the Salmonella typhimurium H flagellar antigen inversion cross-over (hix) recombination sites of the invertible hin region. It has been demonstrated that a plasmid-encoded Hin invertase homologue (FinB), present in B. fragilis NCTC 9343, binds specifically to the invertible regions and the recombination sites have been designated as fragilis inversion cross-over (fix) sites.

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Section: Introductionmentioning

confidence: 99%

Multiple inverted DNA repeats of Bacteroides fragilis that control polysaccharide antigenic variation are similar to the hin region inverted repeats of Salmonella typhimurium

et al. 2003

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“…In addition to MCs, antigenically distinct and within-strain variable large capsules (LCs) and small capsules (SCs) are visible by light microscopy when cultures are grown in a glucose-defined medium ( Fig. 1; Patrick et al, 1986), for which the gene loci remain to be assigned. Populations of B. fragilis enriched for the different capsules can be obtained by using Percoll density-gradient centrifugation.…”

Section: Introductionmentioning

confidence: 99%

“…Potential virulence determinants include expression of within-strain phase and antigenically variable polysaccharides that form a marginal electron-dense layer, or micro-capsule (MC), of approximately 35 nm in size, outwith the outer membrane and not visible by light microscopy ( Fig. 1; Patrick et al, 1986;Lutton et al, 1991). Of the eight PS loci (A-H) that are related to variable MC expression, seven are switched ON and OFF by the site-specific inversion of promoter sequences, where recombination can be mediated by two members of the serine family of invertases (Patrick et al, 2003;Coyne et al, 2003;Liu et al, 2008).…”

Section: Introductionmentioning

confidence: 99%

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Mutational analysis of genes implicated in LPS and capsular polysaccharide biosynthesis in the opportunistic pathogen Bacteroides fragilis

et al. 2009

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The obligate anaerobe Bacteroides fragilis is a normal resident of the human gastrointestinal tract. The clinically derived B. fragilis strain NCTC 9343 produces an extensive array of extracellular polysaccharides (EPS), including antigenically distinct large, small and micro-capsules. The genome of NCTC 9343 encodes multiple gene clusters potentially involved in the biosynthesis of EPS, eight of which are implicated in production of the antigenically variable micro-capsule. We have developed a rapid and robust method for generating marked and markerless deletions, together with efficient electroporation using unmodified plasmid DNA to enable complementation of mutations. We show that deletion of a putative wzz homologue prevents production of highmolecular-mass polysaccharides (HMMPS), which form the micro-capsule. This observation suggests that micro-capsule HMMPS constitute the distal component of LPS in B. fragilis. The long chain length of this polysaccharide is strikingly different from classical enteric O-antigen, which consists of short-chain polysaccharides. We also demonstrate that deletion of a putative wbaP homologue prevents expression of the phase-variable large capsule and that expression can be restored by complementation. This suggests that synthesis of the large capsule is mechanistically equivalent to production of Escherichia coli group 1 and 4 capsules.

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“…They were then stained with uranyl acetate and lead citrate and examined with a Philips 301 transmission electron microscope. Ruthenium red staining was done as described previously (Patrick et al, 1986) before the bacteria were embedded in LR white resin.…”

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Immunochemical Characterization of a Polysaccharide Antigen of Bacteroides fragilis with an IgM Monoclonal Antibody

Reid

Patrick

Tabaqchali³

1987

Microbiology

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~ ~~~~An IgM mouse monoclonal antibody (McAb) Bf4 was produced to a surface polysaccharide of Bacteroidesfiagilis NCTC 9343. Immunoblotting showed that McAb Bf4 reacted strongly with a high molecular mass structure which was sensitive to oxidation with periodate but resisted protease treatment. An inhibition enzyme-linked immunosorbent assay (ELISA) indicated that McAb Bf4 did not cross react with the sixteen Bacteroides species and strains tested. Cells of B..fragilis NCTC 9343 recovered from the various interfaces of a Percoll discontinuous density gradient were tested in the inhibition ELISA. Bacteria from the 0-20%, 20-40% and 40-60% interfaces inhibited the ELISA; however, cells from the 60-80% interface did not. Electron microscopy with immunogold labelling showed that McAb Bf4 did not react with the extracellular fibrous network on bacteria recovered from the 0-20% interface, or the extracellular electron dense layer on cells from the 60-80% interface; however, it was associated with a surface structure on cells from the 20-40% interface. Growth in tivo did not enrich for bacteria with this structure. INTRODUCTXON

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Capsulation of in vitro and in vivo Grown Bacteroides Species

Cited by 19 publications

References 3 publications

Multiple inverted DNA repeats of Bacteroides fragilis that control polysaccharide antigenic variation are similar to the hin region inverted repeats of Salmonella typhimurium

Multiple inverted DNA repeats of Bacteroides fragilis that control polysaccharide antigenic variation are similar to the hin region inverted repeats of Salmonella typhimurium

Mutational analysis of genes implicated in LPS and capsular polysaccharide biosynthesis in the opportunistic pathogen Bacteroides fragilis

Immunochemical Characterization of a Polysaccharide Antigen of Bacteroides fragilis with an IgM Monoclonal Antibody

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