Metabolix is developing environmentally responsible alternatives to petrochemicals in order to meet the global market demand for products that reduce fossil energy use and greenhouse gas emissions.  One of our objectives is to develop microbial strains that enable the commercial-scale production of biodegradable polymers (polyhydroxyalkanoates) and C4/C5 biochemicals from renewable feedstocks.  In particular, the polymers Metabolix is focusing on have material properties that lend themselves to a variety of consumer applications.  In this talk, we will discuss some of our work to construct and introduce novel pathways into microbial strains and to rationally manipulate host metabolism for streamlined production.