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Journal ArticleDOI

Up-Cycling of PET (Polyethylene Terephthalate) to the Biodegradable Plastic PHA (Polyhydroxyalkanoate)

12 Sep 2008-Environmental Science & Technology (American Chemical Society)-Vol. 42, Iss: 20, pp 7696-7701
TL;DR: The conversion of the petrochemical polymer polyethylene terephthalate to a biodegradable plastic polyhydroxyal-kanoate (PHA) is described here and PHA was detected in all three strains when nitrogen depleted below detectable levels in the growth medium.
Abstract: The conversion of the petrochemical polymer polyethylene terephthalate (PET) to a biodegradable plastic polyhydroxyalkanoate (PHA) is described here. PET was pyrolised at 450 °C resulting in the production of a solid, liquid, and gaseous fraction. The liquid and gaseous fractions were burnt for energy recovery, whereas the solid fraction terephthalic acid (TA) was used as the feedstock for bacterial production of PHA. Strains previously reported to grow on TA were unable to accumulate PHA. We therefore isolated bacteria from soil exposed to PET granules at a PET bottle processing plant. From the 32 strains isolated, three strains capable of accumulation of medium chain length PHA (mclPHA) from TA as a sole source of carbon and energy were selected for further study. These isolates were identified using 16S rDNA techniques as P. putida (GO16), P. putida (GO19), and P. frederiksbergensis (GO23). P. putida GO16 and GO19 accumulate PHA composed predominantly of a 3-hydroxydecanoic acid monomer while P. freder...
Citations
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Journal ArticleDOI
TL;DR: In this paper, challenges and opportunities regarding polyhydroxyalkanoate production are presented and discussed, covering key steps of their overall production process by applying pure and mixed culture biotechnology, from raw bioprocess development to downstream processing.
Abstract: Sustainable biofuels, biomaterials, and fine chemicals production is a critical matter that research teams around the globe are focusing on nowadays. Polyhydroxyalkanoates represent one of the biomaterials of the future due to their physicochemical properties, biodegradability, and biocompatibility. Designing efficient and economic bioprocesses, combined with the respective social and environmental benefits, has brought together scientists from different backgrounds highlighting the multidisciplinary character of such a venture. In the current review, challenges and opportunities regarding polyhydroxyalkanoate production are presented and discussed, covering key steps of their overall production process by applying pure and mixed culture biotechnology, from raw bioprocess development to downstream processing.

448 citations

Journal ArticleDOI
TL;DR: This review outlines production and characteristics of PHAs, developments in their production, and applications in various industries including nanotechnology.

423 citations

Journal ArticleDOI
12 Mar 2014-Polymers
TL;DR: This review aims to facilitate the start-up of PHA research by providing a summary of commercially available PHA-accumulating microbial cultures, PHA biosynthetic pathways, and methods for PHA detection, extraction and analysis.
Abstract: With the impending fossil fuel crisis, the search for and development of alternative chemical/material substitutes is pivotal in reducing mankind's dependency on fossil resources. One of the potential substitute candidates is polyhydroxyalkanoate (PHA). PHA is a carbon-neutral and valuable polymer that could be produced from many renewable carbon sources by microorganisms, making it a sustainable and environmental-friendly material. At present, PHA is not cost competitive compared to fossil-derived products. Encouraging and intensifying research work on PHA is anticipated to enhance its economic viability in the future. The development of various biomolecular and chemical techniques for PHA analysis has led to the identification of many PHA-producing microbial strains, some of which are deposited in culture collections. Research work on PHA could be rapidly initiated with these ready-to-use techniques and microbial strains. This review aims to facilitate the start-up of PHA research by providing a summary of commercially available PHA-accumulating microbial cultures, PHA biosynthetic pathways, and methods for PHA detection, extraction and analysis.

357 citations


Cites background from "Up-Cycling of PET (Polyethylene Ter..."

  • ..., polystyrene [PS], polyethylene [PE] and polyethylene terephthalate [PET]) for mcl-PHA production [76,77,80], which offers the potential benefit to off-set waste treatment cost through PHA recovery....

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Journal ArticleDOI
TL;DR: The objective of this review is to outline the advances made in the microbial degradation of synthetic plastics and, overview the enzymes involved in biodegradation.
Abstract: Synthetic plastics are pivotal in our current lifestyle and therefore, its accumulation is a major concern for environment and human health. Petroleum-derived (petro-)polymers such as polyethylene (PE), polyethylene terephthalate (PET), polyurethane (PU), polystyrene (PS), polypropylene (PP), and polyvinyl chloride (PVC) are extremely recalcitrant to natural biodegradation pathways. Some microorganisms with the ability to degrade petro-polymers under in vitro conditions have been isolated and characterized. In some cases, the enzymes expressed by these microbes have been cloned and sequenced. The rate of polymer biodegradation depends on several factors including chemical structures, molecular weights, and degrees of crystallinity. Polymers are large molecules having both regular crystals (crystalline region) and irregular groups (amorphous region), where the latter provides polymers with flexibility. Highly crystalline polymers like polyethylene (95%), are rigid with a low capacity to resist impacts. PET-based plastics possess a high degree of crystallinity (30-50%), which is one of the principal reasons for their low rate of microbial degradation, which is projected to take more than 50 years for complete degraded in the natural environment, and hundreds of years if discarded into the oceans, due to their lower temperature and oxygen availability. The enzymatic degradation occurs in two stages: adsorption of enzymes on the polymer surface, followed by hydro-peroxidation/hydrolysis of the bonds. The sources of plastic-degrading enzymes can be found in microorganisms from various environments as well as digestive intestine of some invertebrates. Microbial and enzymatic degradation of waste petro-plastics is a promising strategy for depolymerization of waste petro-plastics into polymer monomers for recycling, or to covert waste plastics into higher value bioproducts, such as biodegradable polymers via mineralization. The objective of this review is to outline the advances made in the microbial degradation of synthetic plastics and, overview the enzymes involved in biodegradation.

301 citations

References
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Journal ArticleDOI
TL;DR: A new criterion for triggering the extension of word hits, combined with a new heuristic for generating gapped alignments, yields a gapped BLAST program that runs at approximately three times the speed of the original.
Abstract: The BLAST programs are widely used tools for searching protein and DNA databases for sequence similarities. For protein comparisons, a variety of definitional, algorithmic and statistical refinements described here permits the execution time of the BLAST programs to be decreased substantially while enhancing their sensitivity to weak similarities. A new criterion for triggering the extension of word hits, combined with a new heuristic for generating gapped alignments, yields a gapped BLAST program that runs at approximately three times the speed of the original. In addition, a method is introduced for automatically combining statistically significant alignments produced by BLAST into a position-specific score matrix, and searching the database using this matrix. The resulting Position-Specific Iterated BLAST (PSIBLAST) program runs at approximately the same speed per iteration as gapped BLAST, but in many cases is much more sensitive to weak but biologically relevant sequence similarities. PSI-BLAST is used to uncover several new and interesting members of the BRCT superfamily.

70,111 citations

01 Jan 1991

10,143 citations

Journal ArticleDOI
TL;DR: Compounds Used-N”l-Acetyl-n-ornithine was synthesized as previously described and L-Ornithine monohydrochloride was obtained from the Mann Research Laboratories.

4,028 citations

Journal ArticleDOI
TL;DR: The physiological functions of PHB as a reserve material and in symbiotic nitrogen fixation and its presence in bacterial plasma membranes and putative role in transformability and calcium signaling are also considered.

2,654 citations

Journal ArticleDOI
01 Mar 1978
TL;DR: The gas chromatographic method for the determination of poly-β-hydroxybutyric acid (PHB) is characterized by high accuracy and excellent reproducibility, permitting determinations as low as 10−5 g/l.
Abstract: The gas chromatographic method for the determination of poly-β-hydroxybutyric acid (PHB) consists of a mild acid or alkaline methanolysis of poly-β-hydroxybutyric acid directly without previous extraction of PHB from the cells; this is followed by gas chromatography of the 3-hydroxybutyric acid methylester. The method is characterized by high accuracy and excellent reproducibility, permitting determinations as low as 10−5 g/l. Only 4 h is required from sampling from the fermenter till completion of the PHB determination.

1,100 citations

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