Poly-β-hydroxybuterate (PHB), a biodegradable polyester, is accumulated as a storage compound in many species of bacteria. It belongs to a class of polymers called polyhydroxyalkanoates (PHAs). PHA's were originally identified in 1923.However these polymers first came to the attention of industry in the early 1980's when they were recognized as having thermoplastic properties.Monsanto currently markets a form of PHA produced via fermentation under the trade name Biopol™. It is used to make biodegradable plastic products such as credit cards, bottles and disposable drinking cups. However fermentation is an expensive route to production. The use of crop plants genetically engineered to produce PHA's could provide a less expensive source of the plastic and therefore a more attractive alternative to traditional non-biodegradable petrochemical derived plastics. PHB production in plants was first demonstrated in 1992 in transgenic Arabidopsis thaliana by Chris Somerville and coworkers. They showed that PHB production was tolerated by the plant if it was targeted to the chloroplasts.