Bacterial polymer

Teichoic acids (16) are bacterial polymers in which alditols, glycerol, or ribitol are joined through the primary hydroxyl groups via phosphate diester linkages. 

Phosphonomannans (7) are bacterial polymers in which maimo-oligosaccharides are joined by phosphate diester linkages. Phosphonogalactans are present in certain fungi. 

Although such reactions and the consequences with respect to contaminant fate have primarily focused on soluble humic materials (Carter Suffet, 1982 Madhun et al., 1986 Traina et al., 1989 Morra et al., 1990 Puchalski et al., 1992 Engebretson von Wandruszka, 1994), the participation of microbial products in similar reactions is possible. Dohse and Lion (1994) showed that extracellular bacterial polymers enhanced the transport of phenanthrene in sand columns. The mobilization of contaminants might be beneficial to bioremediation if degradation reactions are not inhibited and substrate bioavailability is increased. Conversely, increased contaminant transport may increase the potential for contaminant movement and likewise the extent of environmental contamination. 

Kenis PR, Hoyt JW (1971) Friction reduction by algal and bacterial polymers J Fluid Mech 50 133... 

The sugar nucleotides (an uninformative name that has been used for glycosyl nucleotides, or more strictly, glycosyl esters of nucleoside di- or mono-phosphates) were discussed in this Series12 in 1973. Since then, accumulation of new data about these derivatives has continued, and now, about 35 representatives of this class are known to participate in the biosynthesis of polysaccharide chains of bacterial polymers (for a survey, see Ref. 13). These include glycosyl esters of uridine 5 -diphosphate (UDP), thymidine 5 -diphosphate (dTDP), guanosine 5 -diphosphate (GDP), cytidine 5 -diphosphate (CDP), cytidine 5 -monophosphate (CMP), and adenosine 5 -diphosphate (ADP). 

The ability of nucleoside glycosyl diphosphates to serve as glycosyl phosphate donors in the biosynthesis of polyprenyl glycosyl diphosphates (see Section 11,3) is well documented. It is not yet known whether they may function as immediate precursors of glycosyl phosphate residues not infrequently present as components of bacterial polymers, or whether some other intermediates are involved. 

Polyprenyl glycosyl diphosphates operate mainly as membrane-linked glycosyl acceptors in the biosynthesis of carbohydrate chains of bacterial polymers. In reactions of polymerization of repeating units during polysaccharide synthesis, the polyprenyl diphosphate derivatives serve as donors of growing polysaccharide chain, but monosaccharide transfer from a polyprenyl glycosyl diphosphate has never been detected. 

It seems probable that other L-hexuronic acids listed in Table III, such as L-iduronic,208 2-amino-2-deoxy-L-altruronic,209 and 2,3-diamino-2,3-dideoxy-L-guluronic210 acids may arise in bacterial polymers as a result of epimerization at C-5 at the polymer level. Such a pathway was demonstrated for the biosynthesis of L-idosyluronic acid residues in glycosaminoglycans of higher animals.211 212... 

Two of the most frequent monosaccharide components of bacterial polymers belonging to this group have been the subjects of articles in this Series. They are 3-deoxy-D-manno-2-octulosonic acid,247 a normal constituent of the core region of bacterial lipopolysaccharides that is also present in some other polymers, and N-acetylneuraminic acid,248 found in several capsular polysaccharides. Enolpyruvate phosphate serves as the precursor of the C-l-C-3 fragment of the monosaccharides, with D-arabinose 5-phosphate or 2-acetamido-2-deoxy-D-mannose 6-phosphate being an acceptor for transfer of the three-carbon unit. Characteristic, activated forms of these monosaccharides are the CMP derivatives. 

Keywords Bacterial polymers, extraction methods, biosynthesis, tailor-made synthesis, applications... 

Bacterial Polymers Resources, Synthesis and Applications 293 Table 11.1 (cont.) List of bacterial polymers and applications. 

The goal of this chapter is to provide general information on various bacterial species and the kind of polymers obtained from them. We will also briefly discuss the conventional methods (extraction/isolation), biosynthesis, tailor-made synthesis, and applications of the bacterial polymers. 

Various methods are involved in the isolation or extraction of bacterial polymers from various species. However, here we will only be providing information concerning a few common methods used for the isolation or extraction of various polymers. 

For large-scale recombinant production of bacterial polymers, non-polymer producing bacteria were exposed to biosynthesis pathways. Polymers such as PHA, CGP (cyanophycin granule peptide), HA (hyaluronic acid), and PGA [poly-y-glutamate] were produced by these methods [89, 85-96]. For example, recombinant E.coli [89] was fermented for the lai e-scale production of PHA [89]. In addition the PHB biosynthesis genes of Ralstonia eutropa were harbored in E.coli to produce poljmers such as PHA composed of (R)-S-hydroxybutyrate and (R)-3-hydroxyvalerate and/or (R)-3-hydroxyhexanoate which showed preferable properties for use in industrial applications [97-99, 85-96]. 

The cell as a biosynthesis machine can use cheap carbon sources (waste products) as precursor substrates to produce bacterial polymers. However, the in vitro synthesis of biopolymers requires costly purified key enzymes and precursor molecules such as ATP, coal, coal bolsters, and nucleotide sugars or sugar acids to synthesize polymers such as PHA, cellulose, alginate, and PGA. Consequently, these polymers have limited commercial applicability due to their very high production costs. It is estimated the production of PHB by in vitro synthesis would amount to a cost of around US 286,000 per gram of PHB whereas, bacterial production of PHB was estimated to cost about 0.0025 per gram of PHB, and this is still 5-10 times as expensive to produce as the respective petroleum-based polymers. 

Bacterial polymers obtained by any form (e.g. extraction, biosynthesis methods, tailor-made synthesis) are used for various industrial, agricultural, and biomedical applications [120]. The details of the applications are listed in Table 11.1. 

An improvement of medical devices based on bacterial polymers by the encapsulation of different drugs, opens up the wide prospects in applications for these new devices with pharmacological activity in medicine. PHB polymer was used as a drug delivery matrix for sustaining the release of various drugs such as dipyridamole [DP], indomethacin and antibiotics (rifampicin, metronidazole, ciprofloxacin, levofloxacin), anti-inflammatory drugs (flurbiprofen, dexamethasone, prednisolone), and antitumor drugs (paclitaxel) [132]. 

Currently cellulose (exopolysaccharide) and polyhydroxyalkonates are the most important bacterial polymers which can be profitably used as polymeric material for industrial and medical applications. But it seems to be particularly difficult to achieve a quantitative upgrading of the corresponding extraction, biotechnology and tailor-made synthesis for substantial production at lower prices. Hence, the exploitation of these polymers in various applications will be very difficult until this situation is resolved. Indeed, much awaited is the development of methodologies to increase production of these polymers at affordable prices for more utility. 

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