Itaconic acid is an unsaturated dicarbonic acid which has a high potential as a 
biochemical building block, because it can be used as a monomer for the 
production of a plethora of products including resins, plastics, paints, and 
synthetic fibers. Some Aspergillus species, like A. itaconicus and A. terreus, 
show the ability to synthesize this organic acid and A. terreus can secrete 
significant amounts to the media (>80 g/L). However, compared with the citric 
acid production process (titers >200 g/L) the achieved titers are still low and 
the overall process is expensive because purified substrates are required for 
optimal productivity. Itaconate is formed by the enzymatic activity of a 
cis-aconitate decarboxylase (CadA) encoded by the cadA gene in A. terreus. 
Cloning of the cadA gene into the citric acid producing fungus A. niger showed 
that it is possible to produce itaconic acid also in a different host organism. 
This review will describe the current status and recent advances in the 
understanding of the molecular processes leading to the biotechnological 
production of itaconic acid.