Polysaccharide Fermentations

Moundras, C. Behr, S.R. Demigne, G. Mazur, A. Remesy, G. (1994). Fermentable polysaccharides that enhance fecal bile acid excretion lower plasma cholesterol and apolipoprotein E-rich HDL in rats. Journal of Nutrition, Vol. 124, No.ll, (November 1994), pp. 2179-2188, ISSN 0022-3166. 

Human colonic bacteria are quite versatile with respect to their ability to ferment polysaccharides. Moreover, individual species do not seem to have a consistent strategy for degrading polysaccharides. In some cases, cell-associated periplasmic enzymes are used. In other cases the enzymes are extracellular or even membrane-bound. It may turn out to be the case that the catabolic strategy is specific for the type polysaccharide rather than for the species, i.e. different species may utilize a particular type of polysaccharide in the same way. 

As an alternative to conventional methods of dew and water retting, Murdy [8] investigated the feasibility of silage retting. By applying solid state retting in an enclosed facility, she aimed to recover fermented polysaccharides. 

Classification Fermentation polysaccharide Ionic Nature Anionic... 

Gellan Gum. GeUan gum is the generic name for the extraceUular polysaccharide produced by the bacterium. Pseudomonas elodea (ATCC 31461). Proprietary to Kelco Division of Merck Co., Inc., geUan gum is manufactured in an aerobic, submerged fermentation (76). 

Xanthan gum [11138-66-2] is an anionic heteropolysaccharide produced by several species of bacteria in the genus Aanthomonas A. campestris NRRL B-1459 produces the biopolymer with the most desirable physical properties and is used for commercial production of xanthan gum (see Gums). This strain was identified in the 1950s as part of a program to develop microbial polysaccharides derived from fermentations utilizing com sugar (333,334). The primary... 

The above chemicals can be obtained by fermentation (qv) of other sugars. However, some compounds require sucrose as a unique feedstock. Examples are the polysaccharides dextran, alteman, andlevan, which are produced by specific strains of bacteria (48,54—56). Dextrans are used to make chromatographic separation media, and sulfated dextran derivatives are used as plasma extenders (41). Levans show promise as sweetness potentiators and, along with alteman, have potential as food thickeners and bulking agents in reduced-caloric foods (55,56) (see Carbohydrates). 

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. 

Fiber components are the principal energy source for colonic bacteria with a further contribution from digestive tract mucosal polysaccharides. Rate of fermentation varies with the chemical nature of the fiber components. Short-chain fatty acids generated by bacterial action are partiaUy absorbed through the colon waU and provide a supplementary energy source to the host. Therefore, dietary fiber is partiaUy caloric. The short-chain fatty acids also promote reabsorption of sodium and water from the colon and stimulate colonic blood flow and pancreatic secretions. Butyrate has added health benefits. Butyric acid is the preferred energy source for the colonocytes and has been shown to promote normal colonic epitheUal ceU differentiation. Butyric acid may inhibit colonic polyps and tumors. The relationships of intestinal microflora to health and disease have been reviewed (10). 

Physica.1 Sta.bihty, Physical stabiHty depends primarily on the purity of the enzyme. Impurities remaining from the fermentation broth may precipitate or form a hazy solution. Unwanted sedimentation is often related to Ca " or acidic polysaccharides. The solubiHty of some enzymes can be increased by optimizing the ionic strength or changing the dielectric constant of the solution by a dding low molecular-weight polyols. 

The Structure of a Polysaccharide Synthesized by a Streptococcus Isolated from a Ropy Fermentation, The Value of Infrared Spectroscopy in Polysaccharide Studies, S. A. Barker, F. Pautard, I. R. Siddiqui, and M. Stacey, Chem. Ind. (London), (1955) 1450-1451. 

The same methods (chemicals, enzymes, physical treatments) can be also applied on the cell wall materials not with the aim of extracting polysaccharides but with the aim of obtaining modified fibres. New properties concerning for exemple fermentability, ratio soluble/insoluble dietary fibre, hydration., can be obtained (1). 

A traditional system for the preparation of table olives, involves a treatment of the fresh fruit with a solution of NaOH to hydrolised the bitter glycoside oleuropein, followed by a lactic fermentation in brine. The modifications that take place on pectic polysaccharides of olives (Manzanilla variety) during this process was smdied. Processing induced a net loss of polysaccharides soluble in sodium carbonate and a paralel accumulation of water and Imidazole/HCl soluble polysaccharides. A general decrease of the apparent molecular weight of water and carbonate soluble polysaccharides was also detected. 

Scleroglucan is a polysaccharide secreted by the mycelia of certain microorganisms. It is produced by aerobic fermentation of D-glucose by such microorganisms. Scleroglucan has been proposed as a better alternative to xanthan gum for drilling fluid compositions [666]. 

Most of the xanthan gum used in oil field applications is in the form of a fermentation broth containing 8% to 15% polymer. The viscosity is less dependent on the temperature in comparison with other polysaccharides. 

Fine and specialty chemicals can be obtained from renewable resonrces via multi-step catalytic conversion from platform molecules obtained by fermentation. An alternative method decreasing the processing cost is to carry out one-pot catalytic conversion to final product without intermediate product recovery. This latter option is illustrated by an iimovative oxidation method developed in our laboratory to oxidize native polysaccharides to obtain valuable hydrophilic end-products useful for various technical applications. 

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