Polyhydroxyalkanoates or PHAs are linear polyesters produced in nature by bacterial fermentation of sugar or lipids. They are produced by the bacteria to store carbon and energy. More than 150 different monomers can be combined within this family to give materials with extremely different properties.[1] These plastics are biodegradeable and are used in the production of bioplastics.
To produce PHA, a culture of a micro-organism such as Alcaligenes eutrophus is placed in a suitable medium and fed appropriate nutrients so that it multiplies rapidly. Once the population has reached a substantial level, the nutrient composition is changed to force the micro-organism to synthesize PHA. The yield of PHA obtained from the intracellular inclusions can be as high as 80% of the organism's dry weight.
In the industrial production of PHA, the polyester is extracted and purified from the bacteria by optimizing the conditions of microbial fermentation of sugar or glucose.
In the 1980s, Imperial Chemical Industries developed poly(3-hydroxybutyrate-co-3-hydroxyvalerate) obtained via fermentation that was named "Biopol". It was sold under the name "Biopol" and distributed in the U.S. by Monsanto and later Metabolix.[4]
As raw material for the fermentation, carbohydrates such as glucose and sucrose can be used, but also vegetable oil or glycerine from biodiesel production. Researchers in industry are working on methods with which transgenic crops will be developed that express PHA synthesis routes from bacteria and so produce PHA as energy storage in their tissues. Several companies are working to develop methods of producing PHA from waste water, including start-up Micromidas[5] and Veolia subsidiary Anoxkaldnes.[6]
PHAs are processed mainly via injection molding, extrusion and extrusion bubbles into films and hollow bodies.
Polyhydroxyalkanoates or PHAs are linear polyesters produced in nature by bacterial fermentation of sugar or lipids. They are produced by the bacteria to store carbon and energy. More than 150 different monomers can be combined within this family to give materials with extremely different properties.[1] These plastics are biodegradeable and are used in the production of bioplastics.To produce PHA, a culture of a micro-organism such as Alcaligenes eutrophus is placed in a suitable medium and fed appropriate nutrients so that it multiplies rapidly. Once the population has reached a substantial level, the nutrient composition is changed to force the micro-organism to synthesize PHA. The yield of PHA obtained from the intracellular inclusions can be as high as 80% of the organism's dry weight.In the industrial production of PHA, the polyester is extracted and purified from the bacteria by optimizing the conditions of microbial fermentation of sugar or glucose.In the 1980s, Imperial Chemical Industries developed poly(3-hydroxybutyrate-co-3-hydroxyvalerate) obtained via fermentation that was named "Biopol". It was sold under the name "Biopol" and distributed in the U.S. by Monsanto and later Metabolix.[4]As raw material for the fermentation, carbohydrates such as glucose and sucrose can be used, but also vegetable oil or glycerine from biodiesel production. Researchers in industry are working on methods with which transgenic crops will be developed that express PHA synthesis routes from bacteria and so produce PHA as energy storage in their tissues. Several companies are working to develop methods of producing PHA from waste water, including start-up Micromidas[5] and Veolia subsidiary Anoxkaldnes.[6]
PHAs are processed mainly via injection molding, extrusion and extrusion bubbles into films and hollow bodies.
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