Metabolix Announces That Mirel Bioplastic Has Been Certified Compostable by the Biodegradable Products Institute

BPI Certification Provides Third-Party Validation that Mirel Meets the ASTM
D6400 Standard for Compostable Plastics
CAMBRIDGE, Mass.--(Business Wire)--
Metabolix, Inc. (NASDAQ: MBLX) announced that Mirel bioplastic resins produced
by Telles, its joint venture with Archer Daniels Midland Company, have been
certified compostable by the Biodegradable Products Institute (BPI), an
independent North American certifier of compostable material. BPI certification
shows that Mirel base resins comply with the specifications established in the
American Society for Testing and Materials standard ASTM D6400 for composting in
a professionally managed composting facility.

"Mirel bioplastic resins are now certified by the Biodegradable Products
Institute to be compostable in industrial composting systems," said Steve Mojo,
Executive Director of BPI. "Resin manufacturers are encouraged to use the BPI`s
compostable logo in their marketing efforts to demonstrate their compliance to
ASTM D6400 based on independent testing."

Last month Mirel resins received certifications from Belgium-based Vinçotte of
"OK Compost" for industrial composting and "OK Compost HOME" for home
composting.

"Materials certification is an important process for the bioplastic industry to
embrace," said Bob Findlen, Vice President of Sales and Marketing for Telles.
"Product manufacturers, brand owners, and their customers need to have
confidence that the biodegradability and compostability claims of materials
suppliers are substantiated by scientific data and third party validation."

The BPI`s certification covers Mirel`s base resins. These will be further
compounded into specific grades for use in injection molding, film, sheet, and
thermoforming by manufacturers of products and packaging.

Metabolix and Telles are presenting and exhibiting at NPE 2009, The
International Plastics Showcase, in Chicago, IL the week of June 22, 2009. They
are located at booth #W119020, in the West Hall.

About Mirel Bioplastics

Mirel is a family of bioplastic materials with the physical properties of
petroleum-based resins, yet with a unique combination of being biobased and
biodegradable when disposed in natural soil and water environments, home
composting systems, and in industrial composting facilities in areas where such
facilities are available. The rate and extent of Mirel`s biodegradability will
depend on the size and shape of the articles made from it. However, like nearly
all bioplastics and organic matter, Mirel will not biodegrade in conventional
landfills.

Mirel bioplastics are available for injection molding, blown and cast film, and
cast sheet applications. The first commercial-scale plant to produce Mirel
bioplastic resins is being constructed adjacent to ADM's wet corn mill in
Clinton, Iowa. For more information please visit www.mirelplastics.com.

About Metabolix

Founded in 1992, Metabolix, Inc. is an innovation driven bioscience company
focused on providing sustainable solutions for the world`s needs for plastics,
chemicals and energy. The Company is taking a systems approach, from gene to end
product, integrating sophisticated biotechnology with advanced industrial
practice. Metabolix is now developing and commercializing Mirel, a family of
high performance bioplastics which are biobased and biodegradable alternatives
to many petroleum based plastics. Metabolix is also developing a proprietary
platform technology for co-producing plastics, chemicals and energy, from crops
such as switchgrass, oilseeds and sugarcane.

For more information, please visit www.metabolix.com. (MBLX-G)

ICR
Media:
Matt Lindberg, 203-682-8214
matthew.lindberg@icrinc.com
or
Brian Ruby, 203-682-8268
brian.ruby@icrinc.com
or
Investors:
Anthony Gallo, 203-682-8335
anthony.gallo@icrinc.com

Copyright Business Wire 2009