Bacterial polysaccharides fractionation

In the late 1940s Stacey, with the able and enthusiastic assistance of Paul Kent, examined polysaccharide material from Mycobacterium tuberculosis human strain. From heat-killed cells, two stable, serologically specific polysaccharide fractions and a degraded bacterial glycogen were isolated and examined. 

Adams and coworkers21 also examined the chemical composition and antitumor activity of polysaccharide fractions obtained from the Temple University strain of S. marcescens grown in a medium containing sucrose. Some fractions were obtained from bacterial cells by repeated extraction with aqueous phenol, followed by digestion with... 

The validity of the power law, eq 2, was established in all cases. For atactic polystyrene (a-PS) and polyethylene oxide (PEO) a was found to be 1.5, and rather remarkably, irrespective of solvent quality, in the few instances when the solvent was varied. A value of 1.7 for a has just been reported (9) for the good solvent bromobenzene (not used by us) from a different source. For the bacterial polysaccharide pullulan, which happened to be obtainable in comparatively sharp fractions, a was 1.8 in what is believed to be good solvent (iO). 

With the exception of O-acetyl groups, the deacetylated polysaccharide has a similar composition. The removal of a large amount of insoluble debris is reflected in the composition of the purified polysaccharide fraction. The insoluble debris, which contains the bacterial cells, has not been completely characterized. The debris contains a large proportion of protein, but no carbohydrates. 

Bacterial polysaccharides represent a large variety of polymers biosynthesized by bacteria. Their chemical structures and also their physical properties in solution or in the solid state may vary widely. They often contain uronic acid and then become polyelectrolytes (190). Many new polysaccharides have been developed from bacteria for industrial purposes. Exocellular polysaccharides are produced on a large scale by the usual techniques of microbiology and fermentation. This procedure allows good control of the characteristics of the polymers and allows purification of the polysaccharides more easily than from other natural sources (191-194). Extension of such production also allows reducing the price and extends the range of applications. A good example remains the hyalmonan previously produced by extraction from animal somces but in which some fraction of proteins remained. Bacterial hyaluronan can be prepared in a very pme form (195). 

Fractionation. The process by which components are extracted firm bacterial eells or from the medium in whieh the baeteria are grown and obtained in a purified form. The polysaccharide antigens of Neisseria meningitidis are separated from the bacterial cells by treatment with hexadecyltrimethylammonium bromide and those of Streptococcus pneumoniae with ethanol. The purity of an extracted material may be improved by resolubilization in a suitable solvent and precipitation. After purification, a component may be dried to a powder, stored indefinitely and, as required, incorporated into a vaccine in precisely weighed amounts at the blending stage. 

Dextrans are bacterial and yeast polysaccharides made up of (a 1—>6)-linked poly-D-glucose all have (al—>3) branches, and some also have (al—>2) or (al—>4) branches. Dental plaque, formed by bacteria growing on the surface of teeth, is rich in dextrans. Synthetic dextrans are used in several commercial products (for example, Sephadex) that serve in the fractionation of proteins by size-exclusion chromatography (see Fig. 3-18b). The dextrans in these products are chemically cross-linked to form insoluble materials of various porosities, admitting macromolecules of various sizes. 

The extracellular polysaccharides of Rhizobium meliloti 201 have been examined by using enzymic degradation and chemical procedures.314 A mixture of polysaccharides produced by the bacterium, when incubated with a bacterial enzyme that hydrolyzed one of these, gave oligosaccharides that could be separated by DEAE-cellulose chromatography. The major fraction was a pentasaccharide, for which methylation analysis and Smith... 

Lipolysis in milk is affected by inhibiting and activating factors. As discussed above, proteose peptone fraction of milk can inhibit milk LPL while apolipoproteins stimulate the enzyme. This is particularly important in spontaneous lipolysis however, proteose peptone 3 has been shown to inhibit lipolysis induced by homogenization, sonication, and temperature activation (Arora and Joshi, 1994), while protein components of the milk fat globule membrane inhibit lipolysis caused by bacterial lipase (Danthine et al., 2000). Several exogenous chemical agents can also inhibit lipolysis (Collomb and Spahni, 1995). For example, polysaccharides such as X-carrageenan at 0.3 g/1 effectively inhibits lipolysis in milk activated by mechanical means or temperature manipulation (Shipe et al., 1982) and lipolysis caused by the lipase from P. fluorescens (Stern et al., 1988). 

Endotoxins. Name for bacterial toxins which, in contrast to the exotoxins, are not secreted by living bacteria but are released from the cells by autolysis (e.g. in the intestines). In the case of classic E. they consist of the thermostable lipopolysaccharide (LPS-) fraction of the cell membrane anchored on the outer membranes of Gram-negative bacteria. The LPS consists of lipid A, the chain polysaccharide, and the O-specific chain lipid A is responsible for the toxic action of LPS. E. are found in all Enterobacteriaceae, e.g.. Salmonella (typhus), Shigella (dysentery), and many other Gramnegative pathogens. In the host organism E. stimulate mediators (cytokines) of the immune system. One of... 

Bacterial species can be differentiated by spectral analysis of organic solvent extracts, and by typing spectra of crude capsular polysaccharides. Infrared spectra can be used as d control over processes of inoculation, growth, harvesting, and in the production of fractions to be tested for biologic activity. However, it must be pointed out that rigid standards must be maintained with respect to the use of the spectrophotometer, the incubation time and temperature, culture media, harvest procedures, and the preparation of a dried film on an optical window. 

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