Polyhydroxyalkanoates PHA

Polyhydroxyalkanoates (PHAs) are polyesters that were first isolated and characterized in 1925 by French microbiologist Maurice Lemoigne. They are produced by microorganisms (e.g. Alcaligenes eutrophus mdBacillus megaterium) in response 

Many other polymers of this class are produced by a variety of organisms these include poly-4-hydroxybutyrate (P4HB), polyhydroxyvalerate (PHV), poly-hydroxyhexanoate (PHH), polyhydroxyoctanoate (PHO) and their copolymers. 

Their biosynthetic pathway involves uptake of carbon sources followed by conversion into precursor molecules, which are afterwards polymerized by the PHB synthase [321,322]. Other biosynthetic pathways are involved in fatty acid metabolism. The 

The use of P(3HB) in drug delivery has been extensively studied over the past three decades. Tablets, melt-pressed disks and microspheres have been fabricated for controlled drug release applications [328]. Assesments in-vitro and in-vivo of the activity of the conjugates showed that P(3HB) is indeed a promising material for prolonged drug release systems [329]. 

Polyhydroxyalkanoates have been used as matrices for bone repair in orthopedic applications, in tissue regeneration including nerve tissues and as sutures and films in wound healing [330,331]. Furthermore, the possibility to fabricate electrospun nanofi-brous scaffolds based on polyhydroxyalkanoate has opened a new range of potential applications in the medicinal field [332-334]. 

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Other blends such as polyhydroxyalkanoates (PHA) with cellulose acetate (208), PHA with polycaprolactone (209), poly(lactic acid) with poly(ethylene glycol) (210), chitosan and cellulose (211), poly(lactic acid) with inorganic fillers (212), and PHA and aUphatic polyesters with inorganics (213) are receiving attention. The different blending compositions seem to be limited only by the number of polymers available and the compatibiUty of the components. The latter blends, with all natural or biodegradable components, appear to afford the best approach for future research as property balance and biodegradabihty is attempted. Starch and additives have been evaluated ia detail from the perspective of stmcture and compatibiUty with starch (214). 

Fermentation of Sweet Sorghum into Added Value Biopolymer of Polyhydroxyalkanoates (PHAs)... 

SCHEME 8.11 Ring-opening polymerization of (J-lactones to produce polyhydroxyalkanoates (PHAs). 

Keywords. Polyhydroxyalkanoates, PHA biosynthesis genes, Recombinant bacteria, Fermentation... 

The previous example related to manipulation of primary plant metabolism through creating a bypass within the existing system. There are also a range of studies that have looked at the production of novel substances within plants. One particularly relevant example is the production of a polyhydroxyalkanoate (PHA), polyhydroxybutyrate (PHB), in Arabidopsis thaliana. 

Polyhydric alcohols, 2 46-55 analysis, 2 52-53 chemical reactions, 2 46-50 economic aspects, 2 52 health and safety factors, 2 53 manufacture, 2 50-52 physical properties of, 2 48t uses of, 2 53-54 Polyhydroxyalkanoates (PHA),... 

Polyhydroxyalkanoate (PHA) is a biodegradable and biocompatible thermoplastic that can be synthesized in many microoiganisms from almost all genera of the microbial kingdom. Many microoiganisms synthesize polyhydroxyalkanoates (PHAs) as intracellular carbon and energy reserve materials [1]. These microbial polyesters materials are thermoplastics with biodegradable properties [2]. PHAs are usually accumulated... 

Polyhydroxyalkanoates (PHAs) are biological polyesters that are produced by a wide variety of bacteria as osmotically inert carbon- and energy-storage compounds that accumulate in the form of granules (see Fig. 1). 

Fossil Fuel and Solar Energy Contributions to the Production of Polyethylene (PE), Polylactic acid (PLA), and Polyhydroxyalkanoate (PHA) in kg Fuel/kg Product... 

Polyhydroxyalkanoate (PHA) is a polyester of hydroxyalkanoates synthesized by numerous bacteria as an intracellular carbon and energy storage compound and accumulated as granules in the cytoplasm of cells... 

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