Modulation of isoprenoid gene expression with multiple regulatory parts for improved β-carotene production

Abstract:

Strong promoters might not be optimal to obtain maximum metabolic flux towards desired products, whereas modulating gene expression with multiple regulatory parts is an option to obtain optimal expression strength. Therefore, we assessed the difference of impact on β-carotene production between modulating isoprenoid gene expression with multiple regulatory parts and strong promoter, to improve β-carotene production through combined modulation of essential isoprenoid genes. Eight isoprenoid genes were modulated with six artificial regulatory parts having a wide range of strengths to assess their effects on β-carotene production. Optimal strength for each isoprenoid gene expression was identified, leading to 1.2 to 3.5-fold increase in β-carotene production. In contrast to previous reports, our work suggests that modulating dxr, ispG and ispH genes with appropriate strengths increase β-carotene production. β-carotene yield reached 17.59 mg/g after combined modulation of dxs and idi genes, 8-fold higher than that of the parent strain. Modulating gene expression with multiple regulatory parts was better than strong promoter, providing a new gene modulation strategy for targeted biosynthesis.

Key words:regulatory parts, modulation of gene expression, β-carotene, isoprenoid, Escherichia coli