초록
<P><B>Background</B></P><P>Styrene is an important building-block petrochemical and monomer used to produce numerous plastics. Whereas styrene bioproduction by <I>Escherichia coli</I> was previously reported, the long-term potential of this approach will ultimately rely on the use of hosts with improved industrial phenotypes, such as the yeast <I>Saccharomyces cerevisiae</I>.</P><P><B>Results</B></P><P>Classical metabolic evolution was first applied to isolate a mutant capable of phenylalanine over-production to 357 mg/L. Transcription analysis revealed up-regulation of several phenylalanine biosynthesis pathway genes including <I>ARO3</I>, encoding the bottleneck enzyme DAHP synthase. To catalyze the first pathway step, phenylalanine ammonia lyase encoded by <I>PAL2</I> from <I>A. thaliana</I> was constitutively expressed from a high copy plasmid. The final pathway step, phenylacrylate decarboxylase, was catalyzed by the native <I>FDC1</I>. Expression of <I>FDC1</I> was naturally induced by <I>trans</I>-cinnamate, the pathway intermediate and its substrate, at levels sufficient for ensuring flux through the pathway. Deletion of <I>ARO10</I> to eliminate the competing Ehrlich pathway and expression of a feedback-resistant DAHP synthase encoded by <I>ARO4</I><SUP><I>K229L</I></SUP> preserved and promoted the endogenous availability precursor phenylalanine, leading to improved pathway flux and styrene production. These systematic improvements allowed styrene titers to ultimately reach 29 mg/L at a glucose yield of 1.44 mg/g, a 60% improvement over the initial strain.</P><P><B>Conclusions</B></P><P>The potential of <I>S. cerevisiae</I> as a host for renewable styrene production has been demonstrated. Significant strain improvements, however, will ultimately be needed to achieve economical production levels.</P><P><B>Electronic supplementary material</B></P><P>The online version of this article (doi:10.1186/s12934-014-0123-2) contains supplementary material, which is available to authorized users.</P>