Production of poly-3-hydroxybuytrate in engineered S. cerevisiae

Abstract

Bioplastics produced by microorganisms are an attractive alternative to petroleum-based plastics because they are biodegradable and synthesized from renewable sources. The bioplastic poly-3-hydroxybutyrate (PHB) can be produced in numerous bacteria and yeast species. Large-scale production of PHB has been hindered due to high production costs and relatively low yields. In this study, the PHB biosynthesis pathway was introduced to the yeast S. cerevisiae through metabolic engineering techniques. The main objective of this project was to investigate methods to increase PHB production in engineered S. cerevisiae. Key innovations never done in yeast before include mitochondrial targeting of the PHB pathway and the addition of the phasin protein phaP. PhaP forms a covering around the PHB granule to promote PHB production. Other strategies include the addition of a nonnative acetyl-coA synthetase and reduction of carbon flux to competing pathways such as ethanol and glycerol production.