Metabolix creates bioplastic from switchgrass

By Jerry W. Kram
Web exclusive posted August 15, 2008 at 10:19 a.m. CST

Once upon a time, the one word that expressed economic opportunity was plastics, at least in the iconic movie, The Graduate. Today that word might be bioplastics. While bacteria have been genetically engineered to produce bioplastics for many years, production may soon be as easy as watching the grass grow.

Cambridge, Mass.-based Metabolix Inc. has created a variety of switchgrass that produces significant amounts of polyhydroxyalkanolate (PHA) bioplastics in leaf tissues. The company incorporated multiple genes into the switchgrass genome resulting in a new functional multi-gene pathway in switchgrass. Metabolix recently completed greenhouse trials showing that economically significant amounts of PHA and biomass could be produced by its new varieties.

"Metabolix has been developing technology to produce PHA polymer in switchgrass for over 7 years," said Dr. Oliver Peoples, chief scientific officer for Metabolix. "This result validates the prospect for economic production of PHA polymer in switchgrass, and demonstrates for the first time an important tool for enhancing switchgrass for value-added performance as a bioenergy crop."

Switchgrass has been identified by the U.S. DOE and USDA as a prime feedstock for producing next generation biofuels and bioproducts. The 2007 Energy Independence and Security Act mandated 16 billion gallons of ethanol must be produced by biomass crops, such as switchgrass, by the year 2022.

"A key corporate goal has been to develop value-added industrial crops such as oilseeds, sugarcane and switchgrass," said Richard Eno, president and chief executive officer of Metabolix. "This proof of concept in switchgrass is an important milestone as we develop commercialization strategies for our plant science activities."

PHA is a term for a broad range of plastics including polyhydroxybutyrate, or PHB. PHB has been found to be naturally produced by certain bacteria. Metabolix and Archer Daniels Midland Co. created a joint venture called Telles to produce PHB through fermentation which will be marketed under the brand name Mirel. A facility in Clinton, Iowa, will produce 110 million pounds of Mirel per year and is expected to be operational in the second quarter of 2009.

A detailed scientific paper on the technology, titled "Production of polyhydroxybutyrate in switchgrass, a value-added coproduct in an important lignocellulosic biomass crop," was recently accepted for publication in Plant Biotechnology Journal.