초록
<P>Although many efforts have been made to engineer<I>Escherichia coli</I>for fumaric acid production, the fumarate efflux system has not been investigated as an engineering target to improve fumaric acid production. In this work, we cloned and expressed C4-dicarboxylate transporters of different sources in a previously constructed fumaric-acid-producing strain to study their effects on the production of fumaric acid. In addition, each native C4-dicarboxylate transporter was deleted in separate experiments to investigate their individual effects on fumaric acid production. The results showed that the expression of the genes<I>dcuB-Ec</I>and<I>dcuC-Ec</I>can increase the fumaric acid yield by 48.5% and 53.1%, respectively. Fed-batch cultivations in a 5 L bioreactor of strain<I>A-dcuB-Ec</I>produced 9.42 g L<SUP>−1</SUP>of fumaric acid after 50 hours.</P>