FAIR-CT96-1780 PHAstics: Sustainable Production in Biodegradable Polyesters in Starch-Storing Crop Plants

Contacts
Further Information



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Biotechnology : FAIR Area 1.2 - Green Chemicals and Polymers Chain : Paints/Coatings/Plastics : Plant Genetics : Separation/Fractionation

	Type of Project	Shared Cost
	Contract No	FAIR3-CT96-1780
	Total Cost	1,335,000 ECU
	EC Contribution	800,000 ECU
	Start Date	01/01/1997
	Duration	36 Months

PHAstics: Sustainable production of biodegradable polyesters in starch-storing crop plants

Objectives

Bacterial poly-hydroxy-alkanoates (PHAs) are considered valuable alternatives for fossil oil-derived plastics, because they can be produced from renewable resources and they are biodegradable. However, their production by conventional fermentation technologies is relatively expensive and is limited. For the last few years research has, therefore, focused on the production of PHAs in plants, which has already resulted in the generation of PHA-producing Arabidopsis thaliana and Brassica napus.

Technical Approach

For the current project the application of starch-storing crop plants is anticipated which are considered more suitable for the large-scale accumulation of PHAs.

Expected Results

I. Direct Results

• Isolation and characterisation of bacterial genes involved in mclPHA and PHB synthesis
• Isolation and application of plant genes that mediate the formation of PHA precursors (fatty acids or acetyl-CoA)
• Definition of minimum gene sets required
• Mutant or genetically modified crop plants suitable as hosts for bacterial PHA genes
• Transgenic, hybrid crop plants producing PHAs
• Techniques for the efficient detection, analysis, extraction, downstream processing, up-scaling and development of applications for PHAs from transgenic crop plants

II. Indirect results

The results anticipated may provide information concerning methods how to manipulate the composition and characteristics of plant-derived PHAs. In addition, techniques to be developed may be helpful for the use of starch-storing crop plants for the production of other bio-polymers and heterologous (structural) proteins.

Applications

PHAs will be tested for their applicability in packaging and coating materials for food and diary products. Research on and testing of PHA-coatings will focus on: processing and handling; chemical stability and ageing; water vapour- and gas-transmission rates; adhesion; thermal properties; mechanical properties (tear, tensile, burst, stretch and stiffness); appearance (brightness, gloss, scattering, etc.).

Results To Date

Bacterial pathways are being investigated that lead to the biosynthesis a variety of renewable, biodegradable poly-hydroxyalkanoates (e.g. mcl-PHA, PHB, P3HV, P4HV) in order to determine the minimum gene set required for the production of these PHAs in starch-storing crop plants. A number of bacterial genes phaC1, phbC2, phbA, phbB and phbC have been isolated, characterised and distributed. Most recently, the acyl-CoA transferase (phaG) gene of Pseudomonas putida has been described, which is involved in de novo, glucose-based fatty acid (and PHA) biosynthesis. Also, a truncated, cytosolic form of the Escherichia coli thiosterase (tesA) gene has been implicated with de novo PHA biosynthesis. Transformation vectors have been and are being constructed for potato and pea with plastidial targeting sequences and high expression levels in potato tubers and peas, respectively. Transgenic potato microtubers have been produced expressing the P. oleovorans phaC2 (polymerase) gene with a transcript of the expected size. Transgenic potato plants containing the P. oleovorans phaC1 gene or the Alcaligenes eutrophus phbB and phbC genes are currently being analysed. For pea basta-resistant, putative transformants have been produced possibly each containing one gene of the pathway.

Transgenic microtuber expressing the
Pseudomonas oleovorans PHA polymerase (phaC2) gene

Contacts

Coordinator

• ATO Agrotechnological Research Institute / NETHERLANDS

EC Scientific Officer

• Ciarán MANGAN / European Commission - DG Research Quality of Life Programme - Unit B1.2 / BELGIUM

Participant

• Bernard WITHOLT / Institute of Biotechnology ETH-Hoenggerberg HPT / SWITZERLAND
• Trevor L WANG / John Innes Centre UNITED KINGDOM
• Alexander STEINBUECHEL / Westfaelische Wilhems-Universitaet Muenster Institut fuer Mikrobiologie / GERMANY