초록
<P>Itaconic acid, an unsaturated C5-dicarboxylic acid, is a biobased building block for the polymer industry. The purpose of this study was to establish proof of principle for an anaerobic fermentation process for the production of itaconic acid by modification of the mixed acid fermentation pathway of <I>E. coli</I>. <I>E. coli</I> BW25113 (DE3) and the phosphate acetyltransferase (<I>pta</I>) and lactate dehydrogenase (<I>ldhA</I>) deficient strain <I>E. coli</I> BW25113 (DE3) Δ<I>pta</I>-Δ<I>ldhA</I> were used to study anaerobic itaconate production in <I>E. coli</I>. Heterologous expression of the gene encoding <I>cis</I>-aconitate decarboxylase (<I>cadA)</I> from <I>A. terreus</I> in <I>E. coli</I> BW25113 (DE3) did not result in itaconate production under anaerobic conditions, but 0.08 mM of itaconate was formed when the genes encoding citrate synthase (<I>gltA</I>) and aconitase (<I>acnA</I>) from <I>Corynebacterium glutamicum</I> were also expressed. The same amount was produced when <I>cadA</I> was expressed in <I>E. coli</I> BW25113 (DE3) Δ<I>pta</I>-Δ<I>ldhA</I>. The titre increased 8 times to 0.66 mM (1.2 % Cmol) when <I>E. coli</I> BW25113 (DE3) Δ<I>pta</I>-Δ<I>ldhA</I> also expressed <I>gltA</I> and <I>acnA</I>. In addition, this strain produced 8.5 mM (13 % Cmol) of glutamate. The use of a nitrogen-limited growth medium reduced the accumulation of glutamate by nearly 50 % compared to the normal medium, and also resulted in a more than 3-fold increase of the itaconate titre to 2.9 mM. These results demonstrated that <I>E. coli</I> has potential to produce itaconate and glutamate under anaerobic conditions, closing the redox balance by co-production of succinate or ethanol with H<SUB>2</SUB> and CO<SUB>2</SUB>.</P>