Microbial Polysaccharides Production

Whey permeate may also be fermented anaerobically to fuel gas. Studies have also been reported on the production of ammonium lactate by continuous fermentation of deproteinized whey to lactic acid followed by neutralization with ammonia. Conversion of whey and whey permeate to oil and single-cell protein with strains of Candida curvata and Trichosporon cutaneum have been examined. Production of the solvents n-butanol and acetone by Clostridium acetobutylicum or C. butyricum is under investigation in New Zealand. Whey permeate also has potential for citric acid and acrylic acid manufacture. Extracellular microbial polysaccharide production from whey permeate has... 

Owing to immense competition between microbial and plant polysaccharides for industrial applications, various advance techniques and methodologies have been explored by several researchers to explore flieir stmctural backbone and their associated biological functions. Development of plant polysaccharides is comparatively cheap, while it is uncontrolled and takes place for a short span in a year. On the contrary, microbial polysaccharides production is well regulated and can be sustained fliroughout the year. Nevertheless, fermentation procedures for fabrication of cheap (from plant sources) polysaccharides are not advisable. 

Sutherland IW (1999) Microbial polysaccharide products. Biotechnol Genet Eng... 

Sutherland, I. W. Microbial polysaccharides products. Biotechnol Genet Eng Rev 1999, 16, 217-229. 

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... 

Polarimetric determination of the sucrose concentration of a solution is vaUd when sucrose is the only optically active constituent of the sample. In practice, sugar solutions are almost never pure, but contain other optically active substances, most notably the products of sucrose inversion, fmctose and glucose, and sometimes also the microbial polysaccharide dextran, which is dextrorotatory. Corrections can be made for the presence of impurities, such as invert, moisture, and ash. The advantage of polarization is that it is rapid, easy, and very reproducible, having a precision of 0.001°. 

Commercial applications for polysaccharides include their use as food additives, medicines and industrial products. Although plant polysaccharides (such as starch, agar and alginate) have been exploited commercially for many years, microbial exopolysaccharides have only become widely used over the past few decades. The diversity of polysaccharide structure is far greater in micro-organisms compared to plants and around 20 microbial polysaccharides with market potential have been described. However, microorganisms are still considered to be a rich and as yet underexploited source of exopolysaccharides. 

Dextran is the first microbial polysaccharide produced and utilized on an industrial scale. The potential importance of dextran as a structually (and property) controlled feedstock is clearly seen in light of the recent emphasis of molecular biologists and molecular engineers in the generation of microbes for feedstock production. Dextran is employed as pharmaceuticals (additives and coatings of medications), within cosmetics, as food extenders, as water-loss inhibitors in oilwell drilling muds and as the basis for a number of synthetic resins. 

Microbial polysaccharides have been shown to stress plant cells, resulting in elicitation (induction) and increased metabolite synthesis. Induction of various enzymes has been reported. Chitosan successfully elicited chitinase production in carrot (Daucus carota) cell cultures and elicitation of desired food ingredients and processing aids via chitosan has been attempted. 

In order to provide access here to information about other microbial polysaccharides, there follows a short review of reviews. The Chemical Nature of Bacterial Antigens is a source of information on the earlier work, and this was followed by two reviews - in the present Series in one of these, the bacterial homopolysaccharides were discussed and some of the more complex products were mentioned. A wide review of mucopolysaccharides and mucoproteins included references to many bacterial polysaccharides, and, subsequently, an account of the specific polysaccharides of the Gram-positive Pneumococcus, and of dextrans, levans, and products of Gram-negative forms appeared. There followed a comprehensive review of pneumococcal polysaccharides, and an account restricted to products of Mycobacterium tuberculosis appeared in 1948. A broad coverage was provided in 1950, in this case the products of pathogenic species being dealt with more particularly this work encompassed the basis of the more... 

The degradation of carbohydrates leads, directly or indirectly, to various products, including carbon dioxide, organic acids, microbial polysaccharides, and humic substances. It has often been maintained that carbohydrates are transformed into the dark-colored humic substances by chemical and microbial processes. ... 

Bacterial polysaccharides can also serve as markers to identify specific bacterial species or genera. Typical microbial polysaccharides include peptidoglycans, lipopolysaccharides, and teichoic/teichuronic acids. Some markers such as muramic acid, D-alanine, and p-hydroxy myristic acid are present in the polysaccharides from eubacteria but are uncommon in higher life forms such as plants and animals. Pyrolysis results on bacterial polysaccharides were discussed in Sections 7.9 and 7.10. Specific pyrolysis products such as propionamide or peaks characteristic for KDO have been used for Py-MS or Py-GC/MS characterization of microorganisms. 

Xanthan gum is the most important microbial polysaccharide from the commercial point of view, with a worldwide production of about... 

Microbial polysaccharides from Xanthomonas campestris, notably xanthan gum for use in food industry, have been studied. Other polysaccharides like dextrans, pullulans, scleroglucan were isolated from several microbial sources. Incorporation of xanthan gum in traditional Indian fermented foods like Idli and Dosa has been investigated in elaborate details. Other products with supplementation of xanthan gum which have been investigated include orange and lemon squash, commercial tomato soup, yogurt preparations with or without CMC. Immunological methods for detection of xanthan gum in... 

Several review articles on extracellular polysaccharides have dealt with such topics as the structures of acidic and neutral extracellular microbial polysaccharides, the production of xanthan gums and other bacterial polysaccharides, and the chemistry and biochemistry of microbial extracellular polysaccharides and polysaccharidases. ... 

Most studies on microbial exopolysaccharides production have been performed so far using batch fermentation conditions and polymer macromolecules are recovered from fermentation broths by simple chemical and physical techniques, e.g. precipitation and centrifugation. In Scheme 7.2 the route of production of alginate is presented [8]. Some attempts have been made to apply immobilized-cell cultures to the production of alginate and other bacterial polysaccharides. Immobilization techniques are likely to allow the permanent separation of microbial cells from the incubation broth. In the last few years, however, membrane processes have been increasingly used to separate microbial cells from the production medium. A number of studies have therefore focused on the microfiltration of fermentation broths after batch incubation and the mechanisms of membrane fouling by cells, debris, colloidal particles and macromolecules, e.g. for recovery of polysaccharides from fermentation broths [2]. 

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