Yeast polysaccharides

Polysaccharide Yeast Composition Dose (mg/kg x number) Route Regression Inhibition ratio (%)... 

Ribose, ribose-5-phosphate, hydrolyzed polysaccharides, yeast, and yeast autolysates also appear in the patent literature as carbohydrate sources for these flavorings. There are no economical sources of ribose or ribose-5-phosphate. Yeast and yeast autolysates both will contribute some free carbohydrate. 

Agar, which is low in metabolizable or inhibitory substances, debris, and thermoduric spores, is ideal for the propagation and pure culture of yeasts, molds, and bacteria. Agar also meets the other requirements of ready solubiUty, good gel firmness and clarity, and a gelation temperature of 35—40°C and a gel melting temperature of 75—85°C. A clarified and purified form of the bacterial polysaccharide, geUan gum, is the only known satisfactory substitute. 

Another microbial polysaccharide-based emulsifier is Hposan, produced by the yeast Candida lipolytica when grown on hydrocarbons (223). Liposan is apparentiy induced by certain water-immiscible hydrocarbons. It is composed of approximately 83% polysaccharide and 17% protein (224). The polysaccharide portion consists of D-glucose, D-galactose, 2-amino-2-deoxy-D-galactose, and D-galacturonic acid. The presence of fatty acyl groups has not been demonstrated the protein portion may confer some hydrophobic properties on the complex. 

The function of Jisper Uis fermentation appears to be primarily the breakdown of protein and polysaccharides by secreted proteases and amylases. Replacement oiPispergillis by chemical or enzymatic hydrolysis has no major impact on the organoleptic properties of the sauce. Likewise, inoculation with a pure culture of Ixictobacillus delbrueckii to carry out the acetic acid fermentation produces a normal product. The S. rouxii and Toru/opsis yeasts, however, are specifically required for proper flavor development. 

Many different types of carbohydrate-containing molecules are located on the surface of microbial cells. Some of these are components of die microbial cell wall and are limited to certain types of micro-organisms such as bacterial peptidoglycan, lipopolysaccharides, techoic adds and yeast mannans. Other polysaccharides are not... 

Fungi (whole yeasts capsular polysaccharides proteins)... 

Escot, S. et al.. Release of polysaccharides by yeasts and the influence of released polysaccharides on color stability and wine astringency, Austr. J. Grape Wine Res., 7, 153, 2001. 

This review deals with bacterial and related polysaccharides, such as those of molds and yeasts. The bacteriological nomenclature is that of Bergey10 non-systematic nomenclature is indicated by ( ). 

Although polysaccharide metabolic products of molds and yeasts are not strictly bacterial polysaccharides, they are considered briefly here because of similarities in chemical structure (see also page 191). 

Yeast Insoluble Polysaccharide. The structure of an insoluble polysaccharide from the yeast Saccharomyces cerevisiae was investigated by Zechmeister and Toth,90a and also by Hassid, Joslyn and McCready.904 The isolation904 of 2,4,6-trimethyl-D-glucose as the sole product of the hydrolysis of the methylated polysaccharide indicated a chain of gluco-pyranose units joined by 1,3-glucosidic linkages. 

If branching is (1 —> 3), no glycol grouping will be present in any central unit and it may be seen that reaction will only occur on the terminal units. Such is the case with the polysaccharide laminarin, with the glucan of yeast membrane, and with a galactose-containing polysaccharide isolated from agar.146-148... 

The liquid was then evaporated in vacuo to a small volume and two volumes of 95% ethanol were added. A small amount of flocculent precipitate, probably consisting of yeast polysaccharides, was removed by centrifugation, and the solution was concentrated to a sirup in a vacuum oven at 40°. This colorless sirup, when treated with hot absolute alcohol and stirred, set to a crystalline mass. The crystals were filtered, washed with alcohol and ether and dried in vacuo at 70°. The yield was 2.8 g. 

Polysaccharides from which 2,4,6-trimethyl-D-glucose can be prepared by methylation and hydrolysis include a polyglucose isolated from the cell wall of brewer s yeast,166 laminarin168 and the hemicellulose fraction of Iceland moss.188... 

Yeasts may be identified, and classified, according to the H-l portion of the p.m.r. spectrum of the cell-wall, D-mannose-containing polysaccharide. This portion has served most frequently as a fingerprint for identification of unknown yeasts, but, sometimes, the presence of certain signals of a particular chemical-shift could indicate the presence of certain structures (for example, /3-D-linkages).121 For some... 

When grown at 25°, mycelia, or conidia mixed with mycelia, produce di-O-rhamnosyl side-chains (see the preceding) that are the main, antigenic determinants, as shown by inhibition experiments with oligosaccharides and rabbit immune serum.131 The response of human sera to the polysaccharide, and the fact that 13C-n.m.r. spectroscopy showed that conidia of S. schenckii form a rhamnomannan similar to the yeast component and different from the di-O-rhamnosylman-nan of hyphae,132 suggest the formation of hyphae in vivo. 

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