초록
<P><B>Background</B></P><P>Isoprene, a volatile C5 hydrocarbon, is an important platform chemical used in the manufacturing of synthetic rubber for tires and various other applications, such as elastomers and adhesives.</P><P><B>Results</B></P><P>In this study, <I>Escherichia coli</I> MG1655 harboring <I>Populus trichocarpa</I> isoprene synthase (Pt<I>ispS</I>) and the exogenous mevalonate (MVA) pathway produced 80 mg/L isoprene. Codon optimization and optimal expression of the <I>ispS</I> gene via adjustment of the RBS strength and inducer concentration increased isoprene production to 199 and 337 mg/L, respectively. To augment expression of MVA pathway genes, the MVA pathway was cloned on a high-copy plasmid (pBR322 origin) with a strong promoter (P<SUB>trc</SUB>), which resulted in an additional increase in isoprene production up to 956 mg/L. To reduce the formation of byproducts derived from acetyl-CoA (an initial substrate of the MVA pathway), nine relevant genes were deleted to generate the <I>E. coli</I> AceCo strain (<I>E. coli</I> MG1655 Δ<I>ackA</I>-<I>pta</I>, <I>poxB</I>, <I>ldhA</I>, <I>dld</I>, <I>adhE</I>, <I>pps</I>, and <I>atoDA</I>). The AceCo strain harboring the <I>ispS</I> gene and MVA pathway showed enhanced isoprene production of 1832 mg/L in flask culture with reduced accumulation of byproducts.</P><P><B>Conclusions</B></P><P>We achieved a 23-fold increase in isoprene production by codon optimization of Pt<I>ispS</I>, augmentation of the MVA pathway, and deletion of genes involved in byproduct formation.</P><P><B>Electronic supplementary material</B></P><P>The online version of this article (doi:10.1186/s12934-016-0612-6) contains supplementary material, which is available to authorized users.</P>