초록
<P><B>Abstract</B></P> <P>In this study, the FAD synthesis pathway was manipulated to increase its cellular concentration and thereby improve the electroactivity of <I>E. coli</I>. In a microbial electrosynthesis (MES) system with neutral red as electron carrier and fumarate as the sole electron acceptor, the engineered strains derived from three <I>E. coli</I> lines displayed increased electric current in the reaction system, indicating improved electroactivity. Furthermore, the production of succinate from fumarate increased by around 60% compared with that of the parent strains, confirming the improvement of <I>E. coli</I> electroactivity by manipulating the FAD synthesis pathway. An MES reaction was performed with engineered <I>E. coli</I> 8739, and an altered metabolic profile with more reductive fermentation products was obtained. When the electroactive succinate-producing strain <I>E. coli</I> T110 was used in the MES, a yield of 0.97 ± 0.02 mol/mol glucose was achieved, which corresponds to an approximately 1.4-fold increase compared with the fermentation with no electricity supply or non-electroactive T110. In addition, a carbon concentration mechanism (CCM) was employed to further improve succinate production and yield in the MES, which produced a succinate yield of 1.16 mol/mol glucose, a 1.7-fold increase compared with that of the parent strain T110, indicating that the electroactive <I>E. coli</I> could be used in MES to produce specific fermentation products with improved yield.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Increase of intracellular FAD concentration resulting in electroactive <I>E. coli</I>. </LI> <LI> Neutral red-mediated electrosynthesis is applied to the MES reaction. </LI> <LI> More reductive products are achieved by <I>E. coli</I> 8739(pRibAB-YbjI-YigB, pRibECF). </LI> <LI> The succinate yield is improved by <I>E. coli</I> T110(pRibAB-YbjI-YigB, pRibECF). </LI> </UL> </P>