Increased Isoprene Production by the Recombinant Pantoea ananatis Strain due to the Balanced Amplification of Mevalonate Pathway Genes

Abstract

The uncoordinated expression of a target biosynthetic pathway often results in low growth and productivity for a producing strain due to the accumulation of toxic metabolic intermediates. In this study, we report an increase in isoprene accumulation by an engineered strain of Pantoea ananatis that possesses foreign, artificial mevalonate-pathway genes. This was achieved due to the simultaneous, φ80-Int-dependent integration of a mixture of conditionally replicated plasmids carrying genes for the upper and lower mevalonate pathways and mevalonate kinase, followed by selection according to the isoprene accumulation of clones with optimal copy numbers of the integrative cassettes. A previously developed method, Dual In/Out, was modified to accelerate the construction of recipient strains containing several attB sites of the φ80 phage in their genomes.