Itaconic acid production in Aspergillus was first found in Aspergillus itaconicus. Later on, it was reported to be overproduced by Aspergillus terreus. Currently, itaconic acid is produced commercially by overproducing classical mutants of A. terreus via submerged fungal fermentation. The biosynthesis of itaconic acid in A. terreus occurs via the Embden–Meyerhof–Parnas (EMP) pathway and through the tricarboxylic acid (TCA) cycle. Citric acid is generally considered to be precursor of itaconic acid. Due to the current price of itaconic acid (about US$ 2/kg),its use is restricted. In order to reduce the cost of itaconic acid, the production titer should increase from the current range of 70–90 g/l (Willke and Vorlop, 2001) towards the expected
maximal theoretical yield in the range of 240 g/l. This yield is based on the yield of 360 g/l obtained for the commercial citric acid production process by Aspergillus niger.