| Isoprene is an important platform chemical which is mainly used for the production ofrubber. Isoprene is currently manufactured by the petroleum-based processes. Along with thedecreasing of fossil fuel resources, researchers are seeking for a new isoprene synthesis route.Biosynthesis of isoprene from renewable biomass by microbial transformation is receivingincreasing attention during the past few years due to its sustainable and environmental-friendlyproperties.Dimethylallyl pyrophosphate (DMAPP) and isopentenyl pyrophosphate (IPP) are the twocommon precursors for biosynthesis of isoprenoid compounds. Isoprene can be directlysynthesized from DMAPP under the catalysis of isoprene synthase (ispS) while theinterconversion of DMAPP and IPP can be catalyzed by isopentenyl diphosphate isomerase.Therefore, we propose that the heterogenous expression of isopentenyl diphosphate isomerasewould be beneficial for enhancing isoprene synthesis.In this study, the isopentenyl diphosphate isomerases from Escherichia coli and Bacillussubtilis were cloned and heterogenously overexpressed in E. coli BL21(DE3), respectively. Theexpression levels of the two enzymes were verified by SDS-PAGE analysis. Then their effects onβ-carotene and isoprene biosynthesis in the recombinant strains were further evaluated. Theresults showed that isopentenyl diphosphate isomerase (FNI) from B. subtilis could efficientlypromote the production of the two compounds. In the engineered strains expressing FNI, thetiters of β-carotene and isoprene reached3.25mg/L and2.96mg/L, while the control strainproduced1.08mg/L β-carotene and0.80mg/L isoprene, respectively. For the recombinant strainexpressing IDI, only1.98mg/L β-carotene and0.95mg/L isoprene were obtained.By reconstructing the key step of isoprenoid biosynthesis, the metabolic flux was redirectedand the production of β-carotene and isoprene was greatly improved. This research laid thefoundation for microbial fermentation production of isoprenoid compounds. |
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