Polysaccharide extracellular

Extracellular starch-like materials are produced. Extracellular dextrans are synthesized from sucrose. 

Intracellular and Extracellular Polysaccharides.—Fourier transform infrared 

Chemically defined, highly branched, dextrans have been studied by a C spin-lattice relaxation method. Correlations were made to the positions of carbon atoms associated with branching residues, permitting the values of 0-substitution to be established for D-glucopyranosyl residues. Fourier transform i.r. difference 

The results of the high-temperature enhancement of C n.m.r. chemical shifts of dextrans have been correlated with those of methylation analysis. The diagnostic nature of the 70—75 p.p.m. spectral region with regard to the type of dextran branching, and an increase in resolution of the polysaccharide spectra at higher temperatures, are reported. 

A two-reaction model of Streptococcus mutans adherence to smooth surfaces has been developed. In one reaction, attachment of the cells to the tooth pellicle is mediated by cell-surface proteins rather than D-glucans or teichoic acids. The other reaction is cellular accumulation mediated by sucrose derived D-glucans and cell surface lectins. 

The interactions between cell-free D-glucosyltransferase of S. mutans (serotype d) and water-insduble and water-soluble ( D-glucans of different origin have been reported. The effects of these interactions on de novo o-D-glucan synthesis and adherence to glass surfaces has been considered. 

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Treatment of an extracellular polysaccharide of Rhizobium japonicum (an important factor for nitrogen-fixing symbiosis between bacteria and soybeans) with liquid HF (—40°, 30 min) gave mono- and oligo-saccharides involving 0- -D-glucopyranosyl-( 1 - 3)-C>-(4-0-acetyl-a-D-galactopyrano-syluronic acid)-(l— 3)-D-mannose and its 1-fluoride. 

D-Mannose is common, but L-mannose has only been found in a small group of extracellular polysaccharides of related structures, one of which is elaborated by Alcaligenes ATCC 31555. In these polysaccharides, it is a-linked and partially replaces an a-L-rhamnopyranosyl residue in the pentasaccharide repeating-unit. It seems possible that these sugar residues are scrambled, but the other possibility, that there are two populations of polysaccharides, has not yet been excluded. 

D-Allose and L-altrose are components of the extracellular polysaccharides elaborated by Pseudomonas viscogena and Butyrovibrio fibrisol-vens, respectively. 

Deoxy-L-galactose (L-fucose) is common, and has only been found as the a- or )3-pyranoside. The rare D-fucose has, however, been found both as a-pyranoside, in the LPS frorn Pseudomonas cepacia serotypes B and E, and as a-furanoside, in the cell-wall antigen from Eubacterium saburreum L 452 and the O-antigens from different strains of Psuedomonas syrin-gae The a-furanoside, as in 3, has a cis relationship between the aglycon and OH-2. The corresponding P form has not yet been found. 6-Deoxy-o-and -L-talose are components of the extracellular polysaccharides from some strains of Butyrivibrio fibrisolvens and of the LPS from some strains of E. coli respectively. 

Several glyculosonic acids have been identified as components of bacterial polysaccharides. D-/yxo-Hexulosonic acid, as Q -D-pyranosyl residues (23), is a component of the extracellular polysaccharide from a Rhodococcus species. The LPS from Acinetobacter calcoaceticus NCTC 10305 contains - D-g/ycero-D-/a/o-octulosonic acid (24). It is isosteric with 3-deoxy-D-mnnno-octulosonic acid (25), which is a constituent of bacterial LPS and links the polysaccharide part to the lipid A region. It seems possible that D-g/ycero-D-tfl/o-octulosonic acid replaces 3-deoxy-D-/wan o-octulosonic acid in the A. calcoaceticus LPS. 

A number of 3-deoxyglyculosonic acids have been identified. These substances are acid-labile and are decomposed on hydrolysis with acid under normal conditions, and have therefore often escaped detection in the past. The simplest member of this class, 3-deoxy-L- /yccro-pentulosonic acid (26), occurs as terminal groups in the capsular polysaccharide from Klebsiella K38. Pyranosidic 3-deoxy-D-r/ircohexulosonic acid is a component of the Vibrio parahaemolyticus 07 and 012 LPS. The same acid, as )3-py-ranosyl groups, is also present in the extracellular polysaccharide from Azo-tobacter vinelandii. ... 

Three 3-deoxynonulosonic acids containing amino groups are known. The most abundant of these is 5-amino-3,5-deoxy-D- /yc ro-D-ga/acto-nonulosonic acid (neuraminic acid, 27), which occurs in different extracellular polysaccharides. Some of these, like colominic acid from E. coli K1, are homopolysaccharides. Neuraminic acid is generally A-acetylated and, as in the animal glycoconjugates, has only been found in the a-pyranosyl form (27). It also occurs in some LPS, for example those from some Rhodobacter... 

Several methylated sugars have been identified in hydrolyzates of LPS, cell-wall polysaccharides, and extracellular polysaccharides. A considerable number of these have been found in the LPS from photosynthetic prokaryotes. Two polysaccharides from Mycobacterium species, a glucan" and a mannan" are remarkable in that they contain high percentages of methylated sugars. Glycolipids from Mycobacterium species are also rich in methylated sugars, some of which have not been found elsewhere, but this is beyond the scope of the present article. 

Abbreviations LPS, lipopolysaccharide EPS, extracellular polysaccharide Photosynth., photosynthetic prokaryote. 

Cyclic acetals of pyruvic acid are common in extracellular polysaccharides (compare, for example, Ref. 6). They have also been found in some LPS, namely, those from Shigella dysenteriae type 6 and E. coli 0-149 (Ref. 139), and in the teichoic acid from Brevibacterium iodinum. The biosynthesis of these acetals has already been discussed. 

The pyruvic acid may also be linked to vicinal positions. When linked to 0-3 and 0-4 of a D-galactopyranosyl residue (40), the dioxolane ring becomes cw-fused. In the limited number of known examples, the absolute configuration at the acetalic carbon atom is (S), as in 40. There are some examples of tra -fused dioxolane rings, and these are more sensitive to hydrolysis with acid than the others. Thus, pyruvic acid is acetalically linked to 0-3 and 0-4 of an a-L-rhamnopyranosyl residue in the Klebsiella type 72 capsular polysaccharide, to 0-2 and 0-3 of an a-D-galactopyranosyl residue in the Streptococcus pneumoniae type 4 capsular polysaccharide, and to 0-2 and 0-3 of a S-D-glucopyranosyluronic acid residue in the Klebsiella K1 capsular polysaccharide. " In the extracellular polysaccharide from... 

Several natural polysaccharides are esterified with sulfuric or phosphoric acid. Sulfated bacterial polysaccharides are not, however, very common. One example is a polysaccharide from an Arthrobacter species, which is most probably linked to the proteoglycan and contains sulfated D-galactopy-ranosyl residues. An extracellular polysaccharide from a Phormidium spe-... 

In some polysaccharides, the reducing terminal is linked, through a phosphoric diester linkage, to O-1 of a 2,3-di-6 -acylglycerol. This structural feature has been demonstrated for some capsular polysaccharides from E. coli and Neisseria species, - but is probably more common than that. Non-covalent linkage between the lipid part and the cell membrane may explain why extracellular polysaccharides often occur as capsules, and the high (apparent) molecular weight observed for these polysaccharides may be due to micelle formation in aqueous solution. 

Wagner et al. obtained immunostimulating pectic polysaccharides from plant cell culture of Echinacea purpurea [5]. From the extracellular polysaccharide... 

Cell suspension cultures from H.anmus 1805 which release large amounts of extracellular polysaccharides were investigated. 

A considerable amount of extracellular polysaccharides is produced in the process of cultivation of certain plant suspension cultures and the spent culture medium has proved to be an accessible source for their production (1-3). The interest in investigating these extracellular polysaccharides has been quite strong over the past 10-15 years, motivated by their biological activity (4,5). Plants of the Asteraceae family, as well as their cell cultures, have been established to contain polysaccharides with immunostimulating activity (1-6). The object of our research was Helianthus annuus 1805 cell culture (Asteraceae), which according to the preliminary investigation produces a considerable amount of exopolysaccharides. 

The purpose of this research was to study the time course of growth of the cell culture, the production of extracellular polysaccharides, and their characteristics. 

Experiments were carried out by varying the amount of inoculum (10, 15 and 20 % v/v) to determine the optimal quantity which ensures a steady growth. The time course of growth of the cell suspensions, inoculated with the corresponding amount of inoculum was traced by day-to-day determining the yield of dry cell biomass (7), while the time course of biosynthesis of extracellular polysaccharides was followed by their daily determination, using the carbazole method (9). 

Growth of the Helianthus annuus 1805 cell suspension and biosynthesis of extracellular polysaccharides. A particular characteristic of plant cell suspensions is the requirement for a high inoculation density in order to initiate growth. This is due to one of their special features in order that their growth be initiated when transferred into the new medium, they need certmn growth factors which are released and secreted into the medium by the cells themselves. Consequently, to ensure the growth of plant cell suspensions, a certain volume (in which plant cells have to be present at above certain densities) has to be used to import the necessary quantity of these substances (17). 

It is sometimes claimed that mucilage and similar gels may help to maintain hydraulic conductivity between root and. soil (52). However, the hydraulic conductivity of soils is often substantially decreased when soils are irrigated with waste water. Apart from the inducement of sodicity, which is real in many cases, the decreases in hydraulic conductivity are attributed largely to the production of microbial biomass, particularly extracellular polysaccharides (e.g.. Ref. 53). These extracellular polysaccharides form gels that may store large quantities of water and allow water and ions to diffu.se through them at rates not much less than those of free water, but they could be expected to restrict mass flow of water and thus nutrients, to roots (54). 

Polymeric carbohydrates are usually encountered as distributions, so high resolution is rarely important. Of all biological macromolecules, carbohydrates are particularly amenable to analysis by GPC because hydrophobic interactions are typically weak. A section below is devoted to the analyses of carboxymethylcellulose and xanthan. Other examples of polysaccharides of interest are hyaluronic acid,62 polymers of (l-glucose,121125 heparin,126127 cellulose and chitin,128 and Mucorales extracellular polysaccharides.129... 

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