Production of Enantiomerically Pure (S)-3-Hydroxybutyrate Using Metabolically Engineered Saccharomyces Cerevisiae

(S)-3-Hydroxybutyrate can be used as a precursor to synthesize the biodegradable plastics, polyhydroxyalkalonoates (PHAs) and stereo-specific fine chemicals, such as antibiotics, pheromone and drugs. To produce (S)-3-HB using Saccharomyces cerevisiae, the biosynthetic pathway consisting of three enzymes was introduced into the metabolic pathway of the yeast. To promote maximal activity, we compared the enzymatic activities of each expressed proteins composing the metabolic pathway of 3-HB synthesis. By comparing the in vitro enzymatic activities and in vivo assays by flask cultures of the recombinant strains with ethanol carbon source, the optimal combination of the three enzymes was selected for the maximal production of 3-HB. This is the first report of producing enantiomerically pure (S)-HB using S. cerevisiae.