초록
<P>Through metabolic engineering microorganisms can be engineered to produce new products and further produce these with higher yield and productivities. Here, we expressed the bacterial polyhydroxybutyrate (PHB) pathway in the yeast <I>Saccharomyces cerevisiae</I> and we further evaluated the effect of engineering the formation of acetyl coenzyme A (acetyl-CoA), an intermediate of the central carbon metabolism and precursor of the PHB pathway, on heterologous PHB production by yeast. We engineered the acetyl-CoA metabolism by co-transformation of a plasmid containing genes for native <I>S. cerevisiae</I> alcohol dehydrogenase (<I>ADH2</I>), acetaldehyde dehydrogenase (<I>ALD6</I>), acetyl-CoA acetyltransferase (<I>ERG10</I>) and a <I>Salmonella enterica</I> acetyl-CoA synthetase variant (<I>acs</I><SUP>L641P</SUP>), resulting in acetoacetyl-CoA overproduction, together with a plasmid containing the PHB pathway genes coding for acetyl-CoA acetyltransferase (<I>phaA),</I> NADPH-linked acetoacetyl-CoA reductase <I>(phaB)</I> and poly(3-hydroxybutyrate) polymerase (<I>phaC)</I> from <I>Ralstonia eutropha</I> H16. Introduction of the acetyl-CoA plasmid together with the PHB plasmid, improved the productivity of PHB more than 16 times compared to the reference strain used in this study, as well as it reduced the specific product formation of side products.</P>