Teichoic effectiveness

The walls of Gram-positive bacteria, unlike the membranes, sometimes do not contain teichoic acids. However, there are numerous examples of walls which do contain these compounds in substantial proportions, although in relatively few cases has detailed structural work been carried out. The purification of wall teichoic acids is often much more readily achieved than for the membrane polymers. Addition of ethanol to trichloroacetic acid extracts of walls gives a precipitate which is usually pure teichoic acid. Extraction is effected at low temperatures, and for a reasonably short time, in order to avoid extensive degradation of the polymers under the acidic conditions. Consequently, although walls may contain 20-50% by weight of teichoic acid, practiced yields are generally rather low. 

The teichoic acid shows an infrared absorption band at 1751 cm.-1, characteristic of carboxylic ester groups, which is not observed in samples from which the D-alanine residues have been removed. Removal of the u-alanine was readily effected with ammonia or hydroxylamine, when D-alaninamide or D-alanine hydroxamate were formed. The kinetics of the reaction with hydroxylamine reveal the high reactivity of its D-alanine ester linkages, which, like those in most other teichoic acids, are activated by the presence of a neighboring phosphate group. That the D-alanine residue is attached directly to the ribitol residues, instead of to the d-glucosyl substituents, was also shown by oxidation with periodate under controlled conditions of pH, when it was found that the D-alanine residues protect the ribitol residues from oxidation. Under the same conditions, all of the ribitol residues were oxidized in a sample of teichoic acid from which the D-alanine had been removed, and it is concluded that the ester groups are attached to C-2 or C-3 of the ribitol residues. 

The teichoic acids of the wall and membrane act as a buffer system maintaining a concentration of Mg2 in the range of 10-15 mM, which is the optimum value for the activity of enzymes associated with membranes 31). Changes of the Mg2 + concentration in the medium have no effect on the activity of membrane-bound enzymes if the system keeps both the membrane and the cell wall closely in contact. Preparations devoid of cell walls (lysozyme digestion) exhibit a dependence of enzyme activity on the Mg2 + concentration. The membrane fragments without LTAs show a marked influence of the Mg2+ concentration on enzyme activity 31). 

LAB are Gram-positive bacteria with cell wall components such as peptidoglycan, polysaccharide, and teichoic acid, all of which have been shown to have immunostimulatory properties. In addition to cell wall components, immunostimulatory effects were observed with antigens originated from the cytoplasms of some strains of LAB. 

Studies of the effects of thermal stress on three strains of Staphylococcus aureus have indicated that the teichoic acid in the cell walls aids the survival of the cells by maintaining the accessible pool of Mg ions on the cell surface. A spore-forming Gram-negative bacterium with properties closely similar to those of Bacillus circulans, and which hydrolyses the 2-acetamido-2-deoxy-D-glucosylribitol teichoic acid from Staph, aureus, has been isolated from soil. The immunogenicities of teichoic and lipoteichoic acids from the cell walls and plasma membranes of several oral bacteria that produce lactic acid have been reported. 

In clinical studies of Szmigielski (1982), P. granulosum KP-45 was shown to display immunomodulating, antineoplastic and antiviral effects, which were associated with the activation of monocyte-macrophage system, induction of interferon synthesis and/or activation of killer cells. Stimulation of interferon synthesis was also observed in human tissue cultures. The author suggested that these effects are mediated by the cell wall components, in particular, by peptidoglycans and teichoic acids. 

The ribitol teichoic acid from the cell walls of Staphylococcus aureus in solution binds Mg + ions univalently to phosphate groups and to a counter-ion, in contrast to the cell wall where Mg + ions form bridges across phosphate groups of adjacent chains of teichoic acid. Differences in the affinities between cell walls with or without alanyl ester residues were much greater at low concentrations than they were at high concentrations of Mg + ions. Thus, at very low concentrations of Mg + ions, effective binding to the cell wall is significantly improved... 

Although the cell wall of Spirillum serpens lost much of its rigidity after infection with Bdellovibrio bacteriovorus, the peptidoglycan remained as a discrete cell-wall layer. Comparisons of the abilities of some oligosaccharyl-peptides (obtained from the peptidoglycans of Staph, aureus and Lactobacillus plantarurri) to induce arthritis in rats showed that, at least, one disaccharide unit linked to a peptide is necessary. The presence of teichoic acid did not have any effect. 

Adhesion of microorganisms to the intestinal mucosa is a key feature in colonization and is related to the ability of probiotics to interact with the host in order to exert beneficial health effects. Species- and strain-specific colonization strategies involve proteinaceous compounds as well as teichoic and lipoteicoic acids, peptidoglycans, and EPS. Extracellular proteins, that include cell-envelope and secreted proteins, represent the first-line interaction with the mucus layer of the GIT... 

Beneficial effects of probiotic consumption in the prevention and treatment of several gastrointestinal diseases, such as inflammatory bowel diseases, antibiotic associated-diarrhoea, neonatal necrotizing enterocolitis, irritahle bowel syndrome, Helicobacter pylori infection, as well as food allergies and intolerances, have been clearly assessed (Sanders et al. 2013). Furthermore, probiotics are effective in reducing cholesterol levels and lowering blood pressure (Kumar et al. 2012). However, molecular mechanisms underlying strain-specific probiotic action and the identity of effector molecules (peptidoglycan, teichoic acid, cell surface polysaccharides, extracellular proteins) still remain to be fully elucidated. 

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