Presidential Green Chemistry Challenge: 2005 Small Business Award
Producing Nature's Plastics Using Biotechnology
Innovation and Benefits: Metabolix used new biotechnology methods to develop microorganisms that produce polyhydroxyalkanoates (PHAs) directly. PHAs are natural plastics with a range of environmental benefits, including reduced reliance on fossil carbon, reduced solid waste, and reduced greenhouse gas emissions. PHAs biodegrade to harmless products in the environment, reducing the burden of plastic waste on landfills and the environment. Metabolix hopes to develop plants that produce PHAs as well.
Summary of Technology: Metabolix is commercializing polyhydroxyalkanoates (PHAs), a broadly useful family of natural, environmentally friendly, high-performing, biobased plastics. PHAs are based on a biocatalytic process that uses renewable feedstocks, such as cornstarch, cane sugar, cellulose hydrolysate, and vegetable oils. PHAs can provide a sustainable alternative to petrochemical plastics in a wide variety of applications.
Metabolix uses biotechnology to introduce entire enzyme-catalyzed reaction pathways into microbes, which then produce PHAs, in effect creating living biocatalysts. The performance of these engineered microbes has been fully validated in commercial equipment, demonstrating reliable production of a wide range of PHA copolymers at high yield and reproducibility. A highly efficient commercial process to recover PHAs has also been developed and demonstrated. The routine expression of exogenous, chromosomally integrated genes coding for the enzymes used in a non-native metabolic pathway is a tour de force in the application of biotechnology. These accomplishments have led Metabolix to form an alliance with Archer Daniels Midland Company, announced in November 2004, to produce PHAs commercially, starting with a 100-million-pound-per-year plant to be sited in the U.S. Midwest.
These new natural PHA plastics are highly versatile, have a broad range of physical properties, and are practical alternatives to synthetic petrochemical plastics. PHAs range from rigid to highly elastic, have very good barrier properties, and are resistant to hot water and greases. Metabolix has developed PHA formulations suitable for processing on existing equipment and demonstrated them in key end-use applications such as injection molding, thermoforming, blown film, and extrusion melt casting including film, sheet, and paper coating.
Metabolix's PHA natural plastics will bring a range of environmental benefits, including reduced reliance on fossil carbon and reduced greenhouse gas emissions. PHAs are now made from renewable raw materials, such as sugar and vegetable oils. In the future, they will be produced directly in plants. In addition, PHAs will reduce the burden of plastic waste on solid waste systems, municipal waste treatment systems, and marine and wetland ecosystems: they will biodegrade to harmless products in a wide variety of both aerobic and anaerobic environments, including soil, river and ocean water, septic systems, anaerobic digesters, and compost.
Metabolix's PHA technology is the first commercialization of plastics based on renewable resources that employs living biocatalysts in microbial fermentation to convert renewable raw materials all the way to the finished copolymer product. PHAs are also the first family of plastics that combine broadly useful properties with biodegradability in a wide range of environments, including marine and wetlands ecosystems. Replacement of petrochemical plastics with PHAs will also have significant economic benefits. Producing 50 billion pounds of PHA natural plastics to replace about half of the petrochemical plastics currently used in the United States would reduce oil imports by over 200–230 million barrels per year, improving the U.S. trade balance by $6–9 billion per year, assuming oil at $30–40 per barrel.