In Vitro Synthesis of Isoprene by the Mevalonate Pathway in a Multi-step Enzyme Cascade Immobilized Biocatalyst Based on Mesoporous Molecular Sieve SBA-15

Isoprene is a common monomer in industrial synthetic rubber. We report the in vitro synthesis of isoprene in a multi-step enzyme cascade immobilized biocatalyst by the mevalonate pathway (MVA pathway). This method offers a new way for expanding the biosynthesis of isoprene. The cascade immobilized biocatalyst (PE-SBA-15-FiEs) was constructed by adsorption- cross-linking, with the five key enzymes (mevalonate kinase (MVK), phosphomevalonate kinase (PMK), Mevalonate diphosphate decarboxylase (MVD), isopentenyl disphosphate isomerase (IDI), and isoprene synthetase (ISPS)) of the MVA pathway immobilized on mesoporous molecular sieve SBA-15 as the carrier with polyethylene glycol diglycidyl ether as the cross-linker. At the optimal reaction pH and temperature, the yield of isoprene reached 453.15 mg/L with the PE-SAB-15-FiE, as compared to 274.52 mg/L with the free enzymes. After it had been used five times, the yield of isoprene was still 404.26 mg/L. Furthermore, the yield of isoprene still reached 372.59 mg/L when it was stored for 30 days at room temperature. Thus, the assembled PE-SBA-15-FiEs cascade immobilized biocatalyst has promising application prospects for the industrial production of isoprene. Graphical Abstract