초록
<P><B>ABSTRACT</B></P><P>A multi‐vitamin auxotrophic <I>Torulopsis glabrata</I> strain, a pyruvate producer, was further engineered to produce fumaric acid. Using the genome‐scale metabolic model <I>i</I>NX804 of <I>T. glabrata</I>, four fumaric acid biosynthetic pathways, involving the four cytosolic enzymes, argininosuccinate lyase (ASL), adenylosuccinate lyase (ADSL), fumarylacetoacetase (FAA), and fumarase (FUM1), were found. Athough single overexpression of each of the four enzymes in the cytosol improved fumaric acid production, the highest fumaric acid titer (5.62 g L<SUP>−1</SUP>) was obtained with strain T.G‐ASL<SUB>(H)</SUB>‐ADSL<SUB>(L)</SUB> by controlling the strength of <I>ASL</I> at a high level and <I>ADSL</I> at a low level. In order to further improve the production of fumaric acid, the <I>SpMAE1</I> gene encoding the C<SUB>4</SUB>‐dicarboxylic acids transporter was overexpressed in strain T.G‐ASL<SUB>(H)</SUB>‐ADSL<SUB>(L)</SUB>‐SpMAE1 and the final fumaric acid titer increased to 8.83 g L<SUP>−1</SUP>. This study provides a novel strategy for fumaric acid biosynthesis by utilizing the urea cycle and the purine nucleotide cycle to enhance the bridge between carbon metabolism and nitrogen metabolism. Biotechnol. Bioeng. 2015;112: 156–167. © 2014 Wiley Periodicals, Inc.</P>