Increased production of recombinant pyrroloquinoline quinone (PQQ) glucose dehydrogenase by metabolically engineered Escherichia coli strain capable of PQQ biosynthesis.

We have previously shown that the production of recombinant Escherichia coli PQQGDH was greatly improved by using a medium supplemented with the cofactor PQQ, which is not synthesized in E. coli. We show here that the increase in the accumulated PQQGDH is due to the increased stability of the holo-enzyme over apo-enzyme, using recombinant Acinetobacter calcoaceticus PQQGDH. In order to achieve cost-effective PQQGDH production, we incorporated the genes for PQQ biosynthetic pathway from Klebsiella pneumoniae into E. coli, which as a result allowed E. coli to produce PQQ. Using this metabolically engineered E. coli strain as a host, a 10-fold increase in the production of recombinant A. calcoaceticus PQQGDH was achieved, compared to the condition without PQQ and MgCl2.