Organic acids: Old metabolites, new themes

Israel Goldberg*, J. Stefan Rokem, Ophry Pines

*Corresponding author for this work

Research output: Contribution to journalReview articlepeer-review

232 Scopus citations


Fumaric, L-malic and citric acids are intermediates of the oxidative tricarboxylic acid (TCA) cycle which in eukaryotes is localized in mitochondria. These organic acids are synthesized and accumulated in the medium to very high concentrations by filamentous fungi such as Aspergillus spp. and Rhizopus sp. This article reviews basic research on the unusual acid production capability and the associated metabolic pathways operating under defined stress conditions in these specific fungi. In particular, we describe and discuss the importance of the cytosolic reductive TCA pathway, which includes the cytosolic activities of pyruvate carboxylase, malate dehydrogenase and fumarase, for production of fumaric and L-malic acids. This article also describes the differences between fumaric acid, L-malic acid and citric acid production by different organisms (filamentous fungi, yeast, and higher eukaryotes), and the possible application of novel technologies (genetic engineering and bioinformatics) to fungal systems which may offer new industrial potential of filamentous fungi for the production of valuable metabolites.

Original languageAmerican English
Pages (from-to)1601-1611
Number of pages11
JournalJournal of Chemical Technology and Biotechnology
Issue number10
StatePublished - Oct 2006


  • Aspergillus sp.
  • Citric acid
  • Filamentous fungi
  • Fumaric acid
  • L-malic acid
  • Rhizopus oryzae
  • Tricarboxylic acid (TCA) cycle


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