초록
<P><B>Background</B></P><P>To deal with the increasingly severe energy crisis and environmental consequences, biofuels and biochemicals generated from renewable resources could serve as a promising alternative for replacing petroleum as a source of fuel and chemicals, among which isoprene (2-methyl-1,3-butadiene) in particular is of great significance in that it is an important platform chemical, which has been used in industrial production of synthetic rubber for tires and coatings or aviation fuel.</P><P><B>Results</B></P><P>We firstly introduced fatty acid decarboxylase (OleT<SUB>JE</SUB>) from <I>Jeotgalicoccus</I> species into <I>E. coli</I> to directly convert MVA(mevalonate) into 3-methy-3-buten-1-ol. And then to transform 3-methy-3-buten-1-ol to isoprene, oleate hydratase (OhyA<SUB>EM</SUB>) from <I>Elizabethkingia meningoseptica</I> was overexpressed in <I>E. coli</I>. A novel biosynthetic pathway of isoprene in <I>E. coli</I> was established by co-expressing the heterologous <I>mvaE</I> gene encoding acetyl-CoA acetyltransferase/HMG-CoA reductase and <I>mvaS</I> gene encoding HMG-CoA synthase from <I>Enterococcus faecalis</I>, fatty acid decarboxylase (OleT<SUB>JE</SUB>) and oleate hydratase (OhyA<SUB>EM</SUB>). Furthermore, to enhance isoprene production, a further optimization of expression level of OleT<SUB>JE</SUB>, OhyA<SUB>EM</SUB> was carried out by using different promoters and copy numbers of plasmids. Thereafter, the fermentation process was also optimized to improve the production of isoprene. The final engineered strain, YJM33, bearing the innovative biosynthetic pathway of isoprene, was found to produce isoprene up to 2.2 mg/L and 620 mg/L under flask and fed-batch fermentation conditions, respectively.</P><P><B>Conclusions</B></P><P>In this study, by using metabolic engineering techniques, the novel MVA-mediated biosynthetic pathway of isoprene was successfully assembled in <I>E. coli</I> BL21(DE3) with the heterologous MVA upper pathway, OleT<SUB>JE</SUB> from <I>Jeotgalicoccus</I> species and OhyA<SUB>EM</SUB> from <I>Elizabethkingia meningoseptica</I>. Compared with traditional MVA pathway, the novel pathway is shortened by 3 steps. In addition, this is the first report on the reaction of converting MVA into 3-methy-3-buten-1-ol by fatty acid decarboxylase (OleT<SUB>JE</SUB>) from <I>Jeotgalicoccus</I> species. In brief, this study provided an alternative method for isoprene biosynthesis, which is largely different from the well-developed MEP pathway or MVA pathway.</P><P><B>Electronic supplementary material</B></P><P>The online version of this article (doi:10.1186/s12896-016-0236-2) contains supplementary material, which is available to authorized users.</P>