Yeast produces tailor-made PHA polymers

Researchers at the University of Minnesota genetically engineered Saccharomyces cerevisiae yeast to produce polyhydroxyalkanoate (PHA) polymers composed of monomers ranging from four to 14 carbon atoms. The group genetically engineered the yeast to produce PHA polymers in either the cytosol or peroxisome of the yeast by using intermediates of fatty acid metabolism. The researchers were able to establish beta-oxidation activities from the peroxisomes in the cytosol. As a result, medium-chain (C6 to C14) precursors from both fatty acid degradation and synthesis were supplied to the cytosol, where they were polymerized by medium-chain-length polymerase from Pseudomonas oleovorans expressed there. The synthesis of short-chain length (scl) PHAs in the peroxisome was established by genetically engineering a wild type yeast to express scl polymerase from Ralstonia eutropha in the organelle.