We have chosen three potential biofuel molecules as targets for which we will meta — bolically engineer R. eutropha (Fig. 4). We have targeted three classes of biofuel molecules: butanol, which will be derived from modifications to the PHB pathway; farnesene, which will be produced by introduction of a heterologous pathway to produce isoprenoids; and long-chain alkenes, which will be produced by modifying the fatty acid biosynthesis pathway and introducing genes for alkene biosynthesis. We have genetically modified wild-type R. eutropha to knock out the genes associ­ated with the PHB biosynthesis pathway [15]. We are comparing biofuel production from plasmid-encoded heterologous pathways in the wild-type strain with produc­tion in the PHB- strains.