Capsules Streptococcus

Although it has, to date, not been possible to identify any common structural feature among all the polysaccharide capsules of bacteria associated with the most pathogenic human disease, there is one common feature in many of them. The capsular polysaccharide of type III group B Streptococcus has terminal sialic acid residues in its structure,62,63 as do the groups B and C N. meningitidis and K1 E. coli.3 -34 The ability of terminal sialic acid residues to inhibit the activation of complement by way of the alternative pathway has been well docu-... 

This chapter describes dental caries (tooth decay) and its causes. Sucrose and other mono- and disaccharides are metabolized to acid (lactate) by bacteria that remain in stagnation areas of the teeth. Rats and hamsters fed a 50% sucrose diet developed a caries-sensitive, predominantly gram-positive microbiota that became caries resistant when the rodents were fed penicillin (Sect. 1). Further studies identified Streptococcus mutans (S. mutans) as the etiological agent. This organism synthesizes an insoluble polysaccharide capsule that is stable and retains lactate at the enamel surface (Sect. 2). The key enzyme, glucosyl transferase, is related to salivary amylase which adheres to oral bacteria and enhances bacterial acid production. The chapter concludes with a discussion of salivary and other factors responsible for the marked variation observed in individual caries experience (Sect. 3). 

The probiotic strain E. faecium PR88 was studied in clinical trial (Allen et al. 1996). The consumption of this strain led to alleviation of the symptoms of irritable bowel syndrome in humans. The efficacy and safety of live combmedBifidobacterium, Lactobacillus and Enterococcus capsules in treatment of irritable bowel syndrome was also demonstrated (Fan et al. 2006). E. faecium functions as a probiotic strain inhibiting biofilm formation by Streptococcus mutants, which is an etiological agent for dental caries (Kumada et al. 2008). 

On-the-fly comparison of two gene clusters from Streptococcus pneumoniae for the biosynthesis of differing polysaccharide capsule structures. Sequences will be selected from the public databases for the generation of comparison files and subsequent visualization in ACT. 

GARCIA, V.E., GHERARDI, M.M., IGLESIAS, M.F., CERQUETTI, M.C. SORDELLI, D.O. (1993) Local and systemic immunity against Streptococcus pneumoniae humoral responses against a non-capsulated temperature-sensitive mutant. FEMS Microbiology Letters, 108, 163-167. 

D-Fructofuranosides occur abundantly in Nature. They occur in plants, examples include inulin, levan, and sucrose, and also in bacterial cell-walls and capsules such as those of species of Streptococcus, Haemophilus, and Yersinia 85 Unfortunately, synthesis of their glycosides presents the same type of problem as that in the synthesis of (3-mannosides, namely difficulty of approach of a nucleophile from the [3 side ... 

Lactic acid bacteria synthesise a range of different polysaccharides, defined by their location in the cell. Some are located intracellularly and are used as energy or carbon sources others are cell wall components and some are located outside the cell wall. The latter are called extracellular polysaccharides (EPs) and are either associated with the cell wall as a slime capsule, or secreted into the environment. Many lactic acid bacteria such as Lactobacillus delbrueckii subsp. bulgaricus, Streptococcus thermo-philus and Lactococcus lactis subsp. cremoris produce EPs. 

In addition to helping organisms adhere to surfaces (e.g. Streptococcus mutans and teeth) and protecting them from body defence mechanisms, such as the bactericidal action of serum or ingestion and killing by phagocytes (e.g. the pneumococci and Staphylococcus aureus) capsules probably protect cells from desiccation in natural environments which are prone to periodic drying. Their survival value to the cells therefore justifies the metabolic effort required for their production. 

Hyaluronan can be extracted from the tissue of vertebrate animals (Table 3.1) or from the bacteria that creates the protecting capsule from the polysaccharides. The best bacterial strain for such a purpose is the haemolytic Streptococcus groups A and B. 

A limited amount of gram-positive bacteria (Streptococcus sp. and Pasteurella sp.) are able to synthesize a polysaccharide from the upper capsule (1 mm thick) they create [31,32]. The majority of such microorganisms are pathogenic to humans and animals, but they are also able to parasite in the intercellular space of the mammal s tissue. That is why there is high demand for these microorganisms ... 

Many polysaccharides contain branched structures and are chemically modified by the addition of other molecules. Their monomeric or repeat units are often made up of more than one sugar molecule and, consequently, can be quite complex. They form protective capsules of some of the most virulent microorganisms, capsules that, nevertheless, carry information that activate mammalian defenses the immune, interferon, and properdin systems [9, 136]. They are found as key portions of the exoskeletons of insects and arthropods and cell walls of plants and microbes and perform as reserve foodstuffs and important components of intercellular, mucous secretions, synovial and ocular fluids, and blood serum in many organisms. Food Applications compiles recent data on the food applications of marine polysaccharides from such various sources as fishery products, microorganisms, seaweeds, microalgae, and corals [137, 138]. One of the applications of this biopolymer relates to a method for protecting against diseases induced by Streptococcus pneumoniae infections, which comprises mucosal administration of a S. pneumoniae capsular polysaccharide to a patient in need. 

Dougherty, B.A. van de Rijn, I. Molecular characterization of a locus required for hyaluronic acid capsule production in group A streptococci. J. Exp. Med. 1992, 175, 1291-1299. DeAngelis, P. L. Papaconstantinou, J. Weigel, P.H. Isolation of a Streptococcus pyogenes gene locus that directs hyaluronan biosynthesis in acapsular mutants and in heterologous bacteria. J. Biol. Chem. 1993, 268, 14568-14571. 

Moses AE, Wessels MR, Zalcman K, Alberti S, Natanson-Yaron S, Menes T, Hanski E. Relative contributions of hyaluronic acid capsule and M protein to virulence in a mucoid strain of the group A Streptococcus. Infect Immun 1997 65 64-71. 

Schrager HM, Alberti S, Cywes C, Dougherty GJ, Wessels MR. Hyaluronic acid capsule modulates M protein-mediated adherence and acts as a ligand for attachment of group A Streptococcus to CD44 on human keratinocytes. J Clin Invest 1998 101 1708-1716. 

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