The structure of a mannitol teichoic acid from Bifidobacterium bifidum ssp. Pennsylvanicum

Bifidobacteria cell wall-derived exo-polysaccharides, lipoteichoic acids, peptidoglycans, polar lipids and proteins - their chemical structure and biological attributes

A variety of health benefits has been documented to be associated with the consumption of probiotic bacteria, namely bifidobacteria and lactobacilli. Thanks to the scientific advances in recent years we are beginning to understand the molecular mechanisms by which bacteria in general and probiotic bacteria in particular act as host physiology and immune system modulators. More recently, the focus has shifted from live bacteria towards bacteria-derived defined molecules, so called postbiotics. These molecules may represent safer alternative compared to the live bacteria while retaining the desired effects on the host. The excellent source of effector macromolecules is the bacterial envelope. It contains compounds that are pivotal in the adhesion phenomenon, provide direct bacteria-to-host signaling capacity and the associated physiological impact and immunomodulatory properties of bacteria. Here we comprehensively review the structure and biological role of Bifidobacterium surface and cell wall molecules: exopolysaccharides, cell wall polysaccharides, lipoteichoic acids, polar lipids, peptidoglycans and proteins. We discuss their involvement in direct signaling to the host cells and their described immunomodulatory effects.

Extraction of the same novel homoglycan mixture from two different strains of Bifidobacterium animalis and three strains of Bifidobacterium breve

Three strains of Bifidobacterium breve (JCM 7017, JCM 7019 and JCM 2258) and two strains of Bifidobacterium animalis subsp. lactis (AD011 and A1dOxR) were grown in broth cultures or on plates, and a standard exopolysaccharide extraction method was used in an attempt to recover exocellular polysaccharides. When the extracted materials were analysed by NMR it was clear that mixtures of polysaccharides were being isolated including exopolysaccharides (EPS) cell wall polysaccharides and intracellular polysaccharides. Treatment of the cell biomass from the B. breve strains, or the B. animalis subsp. lactis AD011 strain, with aqueous sodium hydroxide provided a very similar mixture of polysaccharides but without the EPS. The different polysaccharides were partially fractionated by selective precipitation from an aqueous solution upon the addition of increasing percentages of ethanol. The polysaccharides extracted from B. breve JCM 7017 grown in HBM media supplemented with glucose (or isotopically labelled D-glucose-1-¹³C) were characterised using 1D and 2D-NMR spectroscopy. Addition of one volume of ethanol generated a medium molecular weight glycogen (Mw=1×10⁵ Da, yield 200 mg/l). The addition of two volumes of ethanol precipitated an intimate mixture of a low molecular weight β-(1→6)-glucan and a low molecular weight β-(1→6)-galactofuranan which could not be separated (combined yield 46 mg/l). When labelled D-glucose-1-¹³C was used as a carbon supplement, the label was incorporated into >95% of the anomeric carbons of each polysaccharide confirming they were being synthesised in situ. Similar ¹H NMR profiles were obtained for polysaccharides recovered from the cells of B. animalis subsp. lactis AD011and A1dOxR (in combination with an EPS), B. breve JCM 7017, B. breve JCM 7019, B. breve JCM 2258 and from an EPS (-ve) mutant of B. breve 7017 (a non-EPS producer).

Cell wall teichoic acids: structural diversity, species specificity in the genusNocardiopsis, and chemotaxonomic perspective

Data on the structures of cell wall teichoic acids, the anionic carbohydrate-containing polymers, found in many Gram-positive bacteria have been summarized and the polymers of the actinomycete genus Nocardiopsis have been considered from the taxonomic standpoint. The structures of these polymers or their combinations have been demonstrated to be indicative of each of seven Nocardiopsis species and two subspecies, verified by the DNA-DNA relatedness data, and to correlate well with the grouping of the organisms based on 16S rDNA sequences. As each of the intrageneric taxa discussed is definable by the composition of teichoic acids, the polymers are considered to be valuable taxonomic markers for the Nocardiopsis species and subspecies. The (13)C NMR spectra of the polymers, data on the products of their chemical degradation, and distinguishing constituents of whole cell walls derived from teichoic acids are discussed, which are useful for identification of certain polymers and members of the genus Nocardiopsis at the species and subspecies level in microbiological practice.

Isolation and structural analysis of polysaccharide containing galactofuranose from the cell walls of Bifidobacterium infantis

We isolated cell wall polysaccharides (PS-1 and PS-2) from Bifidobacterium infantis Reuter ATCC 15697 and found that the backbone of PS-2 is-->3)-beta-D-Galf-(1-->3)-alpha-D-Galp- (1-->in which beta-D-Galf and alpha-D-Galp are partially substituted at O-6 with beta-D-Glcp. This is the first report of the presence of this disaccharide backbone in a gram-positive bacterium; it resembles the O antigen of some bacteria.

Structural studies on a cell wall polysaccharide from Bifidobacterium longum YIT4028

The major fraction of rhamnogalactan was isolated from the cell wall of Bifidobacterium longum YIT4028 by treatment with N-acetylmuramidase. This polysaccharide was composed of rhamnose and galactose in a molar ratio of about 2:3. The 13C NMR spectrum indicated that it contained a pentasaccharides repeating unit. This observation, and the results of Smith degradation, partial acid hydrolysis and methylation analysis led to the conclusion that its structure is [formula: see text]

Interaction of bifidobacterial lipoteichoic acid with human intestinal epithelial cells

Binding of the lipoteichoic acids of Bifidobacterium bifidum to human colonic epithelial cells appeared to be specific, reversible, and cell concentration and time dependent. A single population of approximately 8.3 X 10(8) binding sites per cell was detected, with a dissociation constant of 125 microM. Ester-linked fatty acids are essential for binding.

Structure of the lipoteichoic acids from Bifidobacterium bifidum spp. pennsylvanicum

The lipoteichoic acids from Bifidobacterium bifidum spp. pennsylvanicum were extracted from cytoplasmic membranes or from disintegrated bacteria with aqueous phenol and purified by gel chromatography. The lipoteichoic acid preparations contained phosphate, glycerol, galactose, glucose and fatty acids in a molar ratio of 1.0:1.0:1.3:1.2:0.3. Chemical analysis and NMR studies of the native preparations and of products from various acid and alkaline hydrolysis procedures gave evidence for the structure of two lipoteichoic acids. The lipid anchor appeared to be 3-O-(6'-(sn-glycero-1-phosphoryl)diacyl-beta-D-galactofuranosyl)-sn-1, 2-diacylglycerol. The polar part showed two structural features not previously described for lipoteichoic acids. A 1,2-(instead of the usual 1,3-) phosphodiester-linked sn-glycerol phosphate chain is only used substituted at the terminal glycerol unit with a linear polysaccharide, containing either beta(1----5)-linked D-galactofuranosyl groups or beta(1----6)-linked D-glucopyranosyl groups.