Metabolix was recently granted or allowed six patents covering technology related to each of our key areas of biopolymers, biobased industrial chemicals and crop-based technologies. Among those granted was patent US 8,487,159, issued on July 16 titled “Production of Polyhydroxybutryrate in Switchgrass.” The patent describes a genetic construct consisting of 3 genes for making PHB, a biopolymer naturally produced in some bacteria as a carbon and energy storage molecule. The patent also describes the invention of switchgrass plants which produce at least 1% dry weight PHB.
This patent particularly drew a lot of interest, including a full technology “Demo” in the MIT Technology Review. Through interviews and a greenhouse tour, we described our research using switchgrass to produce bioplastics and chemicals to reporter David Talbot and photographer Ken Richardson. This article on our crops-based technology combined with a scientific paper from the John Innes Centre in the UK claiming plants can “do math” led to conversations with several reporters. The John Innes paper demonstrates that plants naturally balance the amount of carbon they fix during the day with the amount of carbon they need to get through the night hence the concept that they can do “math.” Given Metabolix commercial targets of 10% by weight PHB in switchgrass without impairing the plants agronomic properties the companies major scientific challenge is to enable the plant to fix more carbon than it normally needs and to direct that carbon through plant metabolism to PHB. This objective can be captured under the broader concept of modifying crops for “enhanced carbon capture” via photosynthesis and “targeted carbon deposition” through metabolic engineering “products of interest” through metabolic engineering. The reporters were very interested in the idea that switchgrass, a perennial high-yielding biomass plant, could be transformed into a value-added crop with the potential to bring value to farmers, as well as a sustainable and cost effective way to make bioplastic and biobased chemicals.
I like to think of a patent as a window into innovation—marking the state of the art at the time of the filing. Metabolix inventors filed the PHB in Switchgrass patent over five years ago, in 2008, and published a paper in the Plant Biotechnology Journal extensively documenting their research titled “Production of polyhydroxybutryrate in switchgrass, a value-added co-product in an important lignosellulosic biomass crop”. In the above scheme this is the “product of interest.” In 2011, Metabolix filed another US Patent application titled “Increasing carbon flow for PHB production in biomass crops.” This pending application describes the design of more complex genetic systems which shift and control carbon flow from the photosynthetic process to increase production of PHB in switchgrass “targeted deposition”. Using this system, the inventors on this patent application described plants that produced 3-7% dry weight PHB. The current focus is on developing systems to enhance the basic photosynthetic systems, “enhanced carbon capture”, such that the plants fix additional carbon to feed this new pathway and further boost PHB levels in plants. We believe that this is a classic case of invention by necessity simply due to the challenging scientific problem we decided to tackle. Interestingly enough our scientists find themselves front and center in what is the major future challenge of agriculture increasing yield. We look forward to describing some of the recent technical success we have achieved in this area as we complete our analysis and new patent filings as well as exploring the potential use of these recent discoveries more broadly in agricultural biotechnology. Our work in switchgrass is supported by our grant from the DOE. We will look forward to reporting more results from our crop program.
Special thanks to Dr. Olly Peoples for his technical review of this blog post.