Construction of Pyrroloquinoline Quinone Synthesis Pathway in Escherichia coli

Abstract:

Currently, the heterologous synthesis of pyrroloquinoline quinone (PQQ) in Escherichia coli is mainly achieved via plasmid vector, which is difficult to systematically optimize the synthesis pathway of multiple gene expression, and easy to cause fermentation instability. In this study, E. coli was used as the chassis organism to systematically optimize the PQQ synthesis at the genome-scale using CRISPR/Cas9 gene editing technology. The operon pqqABCDE from Gluconobacter oxydans 621H was introduced into the chassis E. coli. An engineered strain for highly-efficient synthesis of PQQ was obtained by further optimizing the gene expression strength in the synthesis pathway, knocking out the native inhibitor gene in E. coli, and enhancing the intracellular demand and extracellular transport of PQQ. A total of 86.3 mg/L PQQ was produced after 72 h fermentation in shake-flask. In this study, the construction of efficient PQQ synthesis pathway in the chassis E. coli could provide a reference for future production of PQQ or related metabolites in other chassis.