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Biotechnology Foundation: Metabolic Engineering

Metabolic engineering is the modification of existing, or the introduction of entirely new, metabolic pathways in organisms. Introduction of new pathways enables us to use nature's diversity to meet human needs in a sustainable way. This is a key component of both microbial and plant technology at Metabolix.

Many microorganisms in nature synthesize polyhydroxyalkanoates (Mirels) as an energy storage material, in much the same way animals store fat. These microorganisms can be used in fermentation to produce significant quantities of Mirel Bioplastics, but often they exhibit slow growth, instability, low yields, or difficulties in downstream isolation of Mirels. Metabolic engineering has allowed the creation of microbes with better fermentation characteristics. The Mirel pathways can be optimized, while maintaining the viability of the microbial "biofactory". Existing pathways can be tuned to give better product yields, and novel pathways can be assembled that lead to useful polymer compositions from inexpensive feeds. The enzyme activities used to create these pathways may come from other organisms, or they may originate in the host itself and simply require a regulatory change. Pathways that interfere with efficient Mirel production and storage can be selectively shut down.

Mirel Bioplastic production in plants would not be possible at all without metabolic engineering. But the huge scale and favorable economics of agriculture make plants very compelling metabolic engineering targets. Plants must derive all their own organic compounds from carbon dioxide in the air and the favorable economics of plants make them the ideal, low cost biofactories for Bioplastics.