P-hydroxyalkanoates

Polyesters, such as microbially produced poly[(P)-3-hydroxybutyric acid] [poly(3HB)], other poly[(P)-hydroxyalkanoic acids] [poly(HA)] and related biosynthetic or chemosynthetic polyesters are a class of polymers that have potential applications as thermoplastic elastomers. In contrast to poly(ethylene) and similar polymers with saturated, non-functionalized carbon backbones, poly(HA) can be biodegraded to water, methane, and/or carbon dioxide. This review provides an overview of the microbiology, biochemistry and molecular biology of poly(HA) biodegradation. In particular, the properties of extracellular and intracellular poly(HA) hydrolyzing enzymes [poly(HA) depolymerases] are described. 

Cl in conjunction with a direct exposure probe is known as desorption chemical ionization (DCI). [30,89,90] In DCI, the analyte is applied from solution or suspension to the outside of a thin resistively heated wire loop or coil. Then, the analyte is directly exposed to the reagent gas plasma while being rapidly heated at rates of several hundred °C s and to temperatures up to about 1500 °C (Chap. 5.3.2 and Fig. 5.16). The actual shape of the wire, the method how exactly the sample is applied to it, and the heating rate are of importance for the analytical result. [91,92] The rapid heating of the sample plays an important role in promoting molecular species rather than pyrolysis products. [93] A laser can be used to effect extremely fast evaporation from the probe prior to CL [94] In case of nonavailability of a dedicated DCI probe, a field emitter on a field desorption probe (Chap. 8) might serve as a replacement. [30,95] Different from desorption electron ionization (DEI), DCI plays an important role. [92] DCI can be employed to detect arsenic compounds present in the marine and terrestrial environment [96], to determine the sequence distribution of P-hydroxyalkanoate units in bacterial copolyesters [97], to identify additives in polymer extracts [98] and more. [99] Provided appropriate experimental setup, high resolution and accurate mass measurements can also be achieved in DCI mode. [100]... 

Abate, R. Garozzo, D. Rapisardi, R. BalUstreri, A. Montaudo, G. Sequence Distribution of P-Hydroxyalkanoate Units in Bacterial Copolyesters Determined by-DCI-MS. Rapid Commun. Mass Spectrom. 1992, 6,702-706. 

Another interesting example of lactones are the p-hydroxyalkanoates, whose ROP affords poly(p-hydroxyalkanoate)s (PHAs), a class of aliphatic polyesters naturally produced by bacteria (Fig. 3) [12, 13]. Poly(3-(R)-hydroxybutyrate) (PHB) is a typical example. PHB is a stiff thermoplastic material with relatively poor impact strength, but the incorporation of other monomers can improve the mechanical properties. 

Ajellal N, Thomas CM, Carpentier J-F (2009) Functional syndiotacticpoly(P-hydroxyalkanoate)s via stereoselective ring-opening copolymerization of rac-P-butyrolactone and rac-allyl-P-butyrolactone. J Polym Sci A Polym Chem 47 3177-3189... 

Another example where metabolic pathway engineering has made a dramatic impact is in the biodegradable polymer field. One of the most widely studied polymers in this family is poly-P-hydroxybutyrate (PHB) (64). A related member of the poly-P-hydroxyalkanoate (PHA) family commercialized by Imperial Chemical Industries (ICI), which later became Zeneca Bio Products,... 

Brandi, H., Gross, R. A., Lenz, R. W., and Fuller, R. C. 1988. Pseudomonas oleovorans as a source of poly(P-hydroxyalkanoates) for potential applications as biodegradable polyesters. Appl. Environ. Microbiol.,54,1977-1982. 

A petroleum-degrading strain HD-1 was able to grow autotrophically by using CQ2 as sole carbon source. Inside the cell there accumulated alkane/alkene besides fatty acids or poly-p-hydroxyalkanoic acid. Fatty acids and fatty aldehydes were shown to be reduced to alkane/alkene by anaerobic incubation with the HD-1 cell lysate. 

Fig. 19. Top C-NMR spectra of the amorphous component of solid poly(p-hydroxyalkanoates) as a function of temperature. Spectra were obtained without MAS. Only the aliphatic region is shown, and the backbone and side-chain carbons are labeled bb and sd, respectively. The differential dynamics of the backbone and side chains is evident in the differential line widths. Bottom Schematic behavior of the line width, under conditions of decoupling, when the...

Kim YB, Lenz RW, Fuller RC (1991) Preparation and characterization of poly(P-hydroxyalkanoates) obtained from Pseudomonas oleovorans grown with mixtures of 5-phenylvaleric add and n-alka-noic acids. Macromolecules 24 5256-5260... 

Y.B. Kim, R.W. Lenz, R.C. Fuller, Poly(p-hydroxyalkanoate) copolymers containing brominated repeating units produced by Pseudomonas oleovorans. Macromolecules 25 (1992) 1852-1857, doi 10.1021/ ma00033a002. 

Some micro-organisms, especially bacteria, can synthesise aliphatic polyesters of the poly(p-hydroxy acid)-type, namely poly(P hydroxyalkanoates) (PHA). The natural compound is poly(p-hydroxy... 

Rossignol, H., Boustta, M., Vert, 1999, Synthetic poly(P-hydroxyalkanoates) with carboxylic acid or primary amine pendent groups and their complexes. Intern. J. Biol. Macromol. 25 255-264... 

Fritsche, K., Lenz, R.W., and Fuller, R.C., 1990, Bacterial polyesters containing branched poly(p-hydroxyalkanoate) units. Int.J.Biol.Macromol. 12 92... 

Tombolini R., Nuti M.P. 1989. Poly (P-hydroxyalkanoate) biosynthesis and accumulation by different Rhizobium species. FEMS Microbiol. Letters 60 299-304. 

Phospholipid fatty add assays can also indicate metabolic changes in a microbial community. During nutrient deprivation and other environmental stresses, fatty add ratios can shift. Guckert et al. [36] found increases in the transxis ratio of monoenoic 16-carbon tty adds in Vibrio cholerae during nutrient starvation. The protocol used to extract the lipids fix>m environmental samples simultaneously extracts other biochemical indicators of nutritional status in microbial communities, for example, poly-P-hydroxyalkanoates [31]. 

Green PR, Kemper J, Lee S, Guo L, Satkowski M, Fiedler S, Stembiichel A, Rehm BHA (2002) Formation of short chain length/medium chain length polyhydroxyalkanoate copolymers by fatty acid oxidation inhibited Ralstonia eutropha. Biomacromolecules 3 208—213 Gross RA, DeMeUo C, Lenz RW, Brandi H, Fuller RC (1989) Biosynthesis and characterization of poly(P-hydroxyalkanoates) produced by Pseudomonas oleovorans. Macromolecules 22 1106-1115... 

Gross RA, DeMeUo C, Lenz RW, Brandle H, Fuller RC (1989) Biosynthesis and characterization of poly(P-hydroxyalkanoates) produced by Pseudomonas oleovorans. Macromolecules 22 1106-1115... 

Kim YB, Lenz RW, Fuller RC (1992) Poly(P-hydroxyalkanoate) copolymers containing bromi-nated repeating units produced by Pseudomonas oleovorans. Macromolecules 25 1852-1857 Kim OY, Gross RA, Rutherford DR (1995a) Bioengineering of poly(P-hydroxyalkanoates) for advanced material applications incorporation of cyano and nitrophenoxy side chain substituents. Can J Microbiol 41(Suppl l) 32-43... 

Brandi H, Knee EJ, Fuller RC, Gross RA, Lenz RW (1989) Abihty of the phototrophic bacterium Rhodosprillum rubrum to produce various poly(p-hydroxyalkanoates) potential sources for biodegradable polyesters. Int J Biol Macromol 11 49-55 Caballero KP, Karel SF, Register RA (1995) Biosynthesis and characterization of hydroxybu-tyrate-hydroxycaproate copolymers. Int J Biol Macromol 17 86-92 Chen GQ, Zhang G, Park SJ, Lee SY (2001) Industrial scale production of poly(3-hydroxybu-tyrate-co-3-hydroxyhexanoate). Appl Microbiol Biotechnol 57 50-55 Doi Y (1990) Microbial polyesters. VCH, New York... 

Pouton CW, Majid MIA, Notarianni LJ (1988) Degradation of polyhydroxybutyrate and related copolymers. Proc Int Symp Control Release Bioact Mater 15 182-183 Ramsay BA, Saracovan I, Ramsay JA, Marchessault RH (1994) A method for the isolation of microorganism producing extracellular long-side-chain poly(P-hydroxyalkanoate) depolymerase). J Environ Polym Degrad 2 1-7... 

Many bacteria are a potential source of naturally occurring polyesters, mainly poly (P-hydroxyalkanoate)s with a general structure... 

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