Heteropolysaccharides species

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... 

During start-up, the microbial population distribution in the biofilm varies with time. Initial colonization of the particle may be by one or more species that alter the surface favorably for colonization by other species. For instance, in the operation of a butyrate-degrading fluidized bed bioreactor, methanogens attached to the sand particles early in the start-up process and produced a primary matrix of heteropolysaccharides that allowed attachment of other bacterial species (Sreekrishnan et al., 1991 Zellner et al., 1991 Yongming et al., 1993). This is contrary to findings in an acetate-propionate-butyrate degrading reactor, in which facultative anaerobes were found to be the initial colonizers (Lauwers et al., 1990). 

Properties of Exocellular Heteropolysaccharides from Cryptococcua and Tremella species... 

Peptidoglycans are components of bacterial cell walls and consist of heteropolysaccharide chains cross-linked by short peptide chains. These cell walls bear the antigenic determinants when exposed to them, humans (and other mammalian species) develop specific antibodies to defend against bacteria. Bacterial virulence is also related to substances associated with the cell wall. Cell wall synthesis is the target for the action of the penicillins and cephalosporins. 

In soils nearly 50% of the total sulphur is found in the hydroiodic acid reducible fraction , consisting of sulphate esters, which are probably in part polysaccharide sulphates (e.g. condroitin sulphate), keratin sulphates, choline sulphate, and arylsulphates (Zinder and Brock, 1978b). The heteropolysaccharide sulphates, which are also reported from msirine species (e.g. Torres-Pombo et al., 1969 Abdel-Fattah et al., 1973 Batey and Turvey, 1975), serve mainly as structural materials reaccessible to the marine sulphur cycle as SO ", depending on the ability of microorganisms, plants, and mammals to produce enzymes (sulphhydrolases) to hydrolyze these esters (Fitzgerald, 1978). 

Tremella/Cryptococcus. The first definitive compositional and structural studies (, ) on a member of this family of polysaccharides were done on the heteropolysaccharide produced by C. laurentii var. flavescens NRRL Y-1401. Because haploid, yeastlike species of the basidiomycetous genus Tremella formed glucu-ronoxylomannans (GXM) similar to those from species of Crypto-coccus, a taxonomic relationship was suggested between the genera "(576)7 Basidiomycetous perfect states were subsequently discovered for C. laurentii (7 ) and C. neoformans ( ). 

PS-60 is an anionic heteropolysaccharide that forms viscous solutions and can under certain conditions, form thermoreversible gels with characteristics similar to those formed by both carrageenan and agar. The polysaccharide is produced by a bacterium that was originally isolated from a plant the taxonomy(l) of the organism identifies it as a new species, Pseudo-manos el odea. 

Hemicelluloses are heteropolysaccharides. Their structure and polymeric properties vary depending on the origin, i.e., plant species, industrial processing, isolation and purification procedure. They are a heterogeneous group of polysaccharides. The term was coined at a time when the structures were not well understood and biosynthesis was completely unknown [6]. 

Welan Aicaiigenes species Heteropolysaccharide of glucose, glucuronic acid, and rhamnose with side chains of n repeat of either t-rhammose or t-mannose (1 4 a) or n repeat of glucose(1 units substituted on C3 of every 1,4 linked glucose repeating unit of backbone [d-GIc-(1 4)j8-d-GIcUA-(1 4)j8d-GIc(1 4) a -t-Rha/Man(1 3) P ] ... 

H. are, next to - cellulose and - lignin, the most abundant natural organic chemicals in the biosphere, present in all parts of plants, concentrated in the primary and secondary layers of the cell wall and closely associated with cellulose and lignin. Their biological function are in coimecting and integrating in plant tissues. Some annual as well as hardwood plant species may contain up to 35% h as - pentosans (xylan). H. are heteropolysaccharides. Composition and structure differ widely based on the plant source. 

---