초록
<P><I>Aspergillus carbonarius</I> has a potential as a cell factory for production of various organic acids. In this study, the organic acid profile of <I>A. carbonarius</I> was investigated under different cultivation conditions. Moreover, two heterologous genes, <I>pepck</I> and <I>ppc</I>, which encode phosphoenolpyruvate carboxykinase in <I>Actinobacillus succinogenes</I> and phosphoenolpyruvate carboxylase in <I>Escherichia coli,</I> were inserted individually and in combination in <I>A. carbonarius</I> to enhance the carbon flux toward the reductive TCA branch. Results of transcription analysis and measurement of enzyme activities of phosphoenolpyruvate carboxykinase and phosphoenolpyruvate carboxylase in the corresponding single and double transformants demonstrated that the two heterologous genes were successfully expressed in <I>A. carbonarius.</I> The production of citric acid increased in all the transformants in both glucose- and xylose-based media at pH higher than 3 but did not increase in the pH non-buffered cultivation compared with the wild type.</P><P><B>Electronic supplementary material</B></P><P>The online version of this article (doi:10.1007/s10295-015-1688-4) contains supplementary material, which is available to authorized users.</P>