Xanthanonic acid


Although there are hundreds of different products and as many companies producing them, relatively few products rank ia aimual worldwide sales above 50,000,000. Included in this small group are the antibiotics, bacitracin, cephalosporins, erythromycin, gentamicins, kanamycin, neomycins, penicillins, tetracycline, tylosin, and some newer additions the enzymes amylases, diagnostic enzymes, glucose isomerase, rennet and proteases citric and gluconic acids ethanol vitamin B 2 amino acids, MSG, L-lysine, L-tryptophan, t.-phenylalanine, L-aspartic acid and miscellaneous substances, eg, ergot alkaloids, L-sorbose for vitamin C synthesis, xanthan gum, and insulin. Setting aside the tremendous volume of potable ethanol produced by fermentation, the nearly 470,000 t of MSG and approximately 325,000 t of citric acid produced per year represent the top end of the volume scale (Table 4). Fermentation product sales in the United States are presented in Table 5. The 1992 U.S. market share by sales volume for the top 10 fermentation companies is as follows  [c.183]

Guar gum is compatible with other common plant gums, starch, and water-soluble proteins such as gelatin, except for the synergistic viscosity increases given by blends with xanthan gum (55). The presence of salts, water-miscible solvents or low molecular weight sugars can affect the hydration rate. Small amounts of borate, however, cross-link the guar to form mbbery gels (56). These gels can be reversed by adjusting the pH to the acid ranges.  [c.435]

Concentrations above 0.3% form a gel with borate which is reversible upon the subsequent addition of mannitol (a sequestrant for borate) or of acid. Usefiil combinations are formed with carrageenan (63) and xanthan gum (64) and agar. In many appHcations, it is used in combination with these gums at considerable cost savings.  [c.435]

Structure nd Conformation. As subsequendy found for all microbial polysaccharides, the primary stmcture consists of regular repeating units. Each unit contains five sugars two glucose units, two mannose units, and one glucuronic acid unit. The main chain of xanthan gum is built up of P-D-glucose units linked through the 1- and 4-positions, ie, the chemical stmcture of the main chain of xanthan gum is identical to the chemical stmcture of ceUulose. A three-sugar side chain is linked to the 3-position of every other glucose residue in the main chain (78). About half of the terminal D-maimose residues contain a pymvic acid residue linked to the 4- and 6-positions. The distribution of these pymvate groups is unknown. The nonterminal D-maimose unit in the side chain contains an acetyl group at position 6.  [c.436]

Structure of xanthan has been determined by chemical degradation and methylation analysis (335,336) it is composed of repeating units consisting of a main chain of D-glucopyranosyl residues with trisaccharide side chains made up of D-mannopyranosyl and D-glucopyranosyluronic acid residues.  [c.302]

Low molecular weight (1000—5000) polyacrylates and copolymers of acryflc acid and AMPS are used as dispersants for weighted water-base muds (64). These materials, 40—50% of which is the active polymer, are usually provided in a Hquid form. They are particularly useful where high temperatures are encountered or in muds, which derive most of their viscosity from fine drill soHds, and polymers such as xanthan gum and polyacrylamide. Another high temperature polymer, a sulfonated styrene maleic—anhydride copolymer, is provided in powdered form (65,66). AH of these materials are used in relatively low (ca 0.2—0.7 kg/m (0.5—2 lb /bbl)) concentrations in the mud.  [c.180]

Xanthan. Xanthan, known commercially as xanthan gum [11138-66-2], has a main chain of (1 — 4)-linked P-D-glucopyranosyl units therefore, the chemical stmeture of the main chain is identical to the stmeture of cellulose [9004-34-6]. However, in xanthan, every other P-D-glucopyranosyl unit in the main chain is substituted on 0-3 with a trisaccharide unit. The trisaccharide side chain consists of (reading from the terminal, nonreducing end in towards the main chain) a -D-mannopyranosyl unit linked (1 — 4) to a P-D-glucopyranosyluronic acid unit linked (1 — 2) to a  [c.488]

Microbial polysaccharides may be categorized into groups based on the types of monomer units present. Two of the most important types of microbial polysaccharides are neutral homopolysaccharides and anionically charged heteropolysaccharides. Other groups also exist, such as charged homopolysaccharides, but are of limited occurrence and not commercially significant as of this writing. Homopolysaccharides consist of a single type of monosaccharide, some examples being puUulan and dextran, both of which are polymers of D-glucose [50-99-7]. Some important anionic heteropolysaccharides are xanthan, which contains both neutral sugar and uronic acid residues within its stmcture, and alginic acid, which consists of two different types of uronic acid. Stmctures can be compUcated by the presence of noncarbohydrate groups attached to the carbohydrate chains. Such groups include 0-acetyl esters, and 1-carboxyethylidene (or pymvate) ketals.  [c.295]

Although cellulose [9004-34-6] is usually thought of as a plant-derived polysaccharide, there does exist one weU-known example of cellulose (qv) production by a bacterium. In 1886, a bacterial isolate from what was referred to as the vinegar plant was described. This bacterium, yAcetobacteryylinum, produced a tough, membranous pellicle in Hquid cultures. Using the best methods then available, it was concluded that the pellicular material was cellulose (54), which was later confirmed by chemical methods and x-ray diffraction (55). M. y linum has become a usehil model in the study of cellulose biosynthesis (56,57). The extracellular pellicle is composed primarily of microfibrils of cellulose, a P (1 — 4)-1inked D-glucan. These microfibrils, which consist of parallel chains of polysaccharide molecules, form ribbon-like arrays, which in turn make up the pellicle itself (56,58). Values for the average molecular weight vary, but are typically in the range of 350,000 to 975,000, corresponding to average chain lengths of approximately 2000 to 6000 glucose residues. The polymer chains are synthesized by a membrane-associated enzyme complex. The precursor is the nucleotide phosphate—sugar ester uridine disphosphate—glucose (UDP—glucose), and synthesis seems to proceed through a lipid-linked intermediate (56), although there is still some disagreement as to the exact mechanism of biosynthesis. Part of the problem with studying cellulose biosynthesis inM. y linum is that the bacteria also produce other polysaccharides (59), some of which also contain P-inked D-glucose units. These include P(1 — 2)-linked D-glucans (60) and heteropolysaccharides such as acetan (61,62). Acetan appears to be stmcturaHy related to xanthan as well as to cellulose in that it consists of a P(1 — 4)-1inked D-glucan backbone with side-chain units containing D-glucose, D-mannose, and D-glucuronic acid, as well as terminal L-rhamnose residues (62). Because it is possible that these polysaccharides are all produced by similar mechanisms, the difficulty in separating the enzymes and intermediates involved in the biosynthesis of each is considerable.  [c.296]

A wide variety of organic polymers serve a number of useful purposes ia drilling fluids, the most important of which are to iacrease viscosity and control filtration rates (Table 5). These polymers are either natural polysaccharides, eg, s. 2nxh.[9005-25-8] (qv),guar gum, xanthan gum [11138-66-2] and other biopolymers (see Gums Microbialpolysaccharides) or derivatives of natural polymers, eg, cehulose (qv), lignosulfonate, and lignite and synthetic polymers, eg, polymers and copolymers of acryflc acid, acrylonittile, acrylamide, and 2-acrylamido-2-methylpropanesulfonic acid (AMPS). The most commonly used polymeric viscosity budders are the cehulosics, xanthan gum, and polyacrylamides.  [c.178]

Complex carbohydrates (qv) such as microbially produced xanthan, curdlan, puUulan, hyaluronic acid, alginates, carageenan, and guar are accepted as biodegradable and are finding uses where cost is not an impediment. Xanthan is the predominant microbial polysaccharide on the market, ca 10,000 t worldwide (59), and finds use in the food industry and as a thickener in many industrial apphcations (see Gums). It is foreseeable that other polysaccharides will gain acceptance in specialty areas where biodegradabihty is essential.  [c.477]

The coalescence of internal phase droplets can be further decreased by raising the viscosity of the external contiauous phase through additioa of gums or syathetic polymers, for example, ceUulosic gums such as hydroxypropylmethyl-ceUulose [9004-65-3] fermentation gums such as xanthan gum [11138-66-2] or cross-linked carboxyvinyl polymers such as carbomer [39007-16-3J. The iacreased viscosity also counteracts changes ia the emulsion resultiag from differeaces ia the specific gravity of the two phases as mandated by Stokes law. An advance ia cosmetic emulsificatioa technology has resulted from the development of cross-linked carboxyvinyl polymers, ia which some of the carboxylic acid residues are esterified with various fatty alcohols. These polymers possess the ability to act as primary emulsifiers and thicken the system when some of the remaining carboxylic groups are neutralized with alkali (see Carboxylic acids).  [c.294]

Bindings and Thickenings Ag ent. The rheological properties of a dentifrice are primarily determined by the agent used to bind and thicken the product and allow its extmsion as a firm, but easily dispersible, ribbon. A weU-formulated toothpaste exhibits a high yield point and thixotropy, that is, it is easily Uquified (see RpiEOLOGiCALmeasurements). Gums and resins are employed to obtain the desired thickening and binding. Each has a characteristic rheological spectmm and lends stmcture to the toothpaste accordingly. Gums and resins widely used include acrylic acid polymers, carrageenan [9000-07-17, sodium carboxymethyl cellulose [9004-32-4], xanthan gum [11138-66-2], and hydrated siUca [10279-57-9]. Each is available in several variations having different properties. Selection of an optimal gum or resin along with the selection of appropriate other ingredients results in a paste that extmdes with the apphcation of minimal pressure to form a smooth, cohesive ribbon, which stands up on the toothbmsh bristles and breaks down and disperses quickly in the mouth during bmshing.  [c.502]

The synthetic polymers commonly used in completion fluids are HEC and Xanthan gum (XC Polymer). Xanthan gum is a biopolymer that provides good rheological properties and that is completely soluble in HCl. HEC-hydroxyethyl cellulose is currently the best viscosifer. It gives good carrying capacity, fluid loss control, and rheology it is completely removable with hydrochloric acid. The effect of HCl on the restored permeability for HEC completion fluid is shown in Figure 4-124 and Table 4-68 [36]. It can be noticed that 100% of the original core permeability was restored by displacing acid-broken HEC with brine. The comparison of permeability damage caused by different polymers is given in Table 4-69 [36].  [c.710]


See pages that mention the term Xanthanonic acid : [c.178]    [c.486]    [c.129]    [c.521]   
Thin-layer chromatography Reagents and detection methods (1990) -- [ c.89 ]