Itaconic acid is one of the basic chemicals for the polymer industry, which can be produced on the basis of renewable raw materials. Since the middle of the twentieth century, itaconic acid has been produced industrially using the filamentous fungus Aspergillus terreus. But the demand for the organic acid is low due to the high production costs compared to alternative petrochemical manufactured raw materials. The high production costs are based on a low final titer, low productivities, and the usage of pure sugars, purified molasses, or starch hydrolysates, since the fungus reacts very sensitively to impurities in a culture medium. This review provides a comprehensive overview of the most recent developments, including a spectrum of studied microorganisms and their capabilities for the production of itaconic acid. The technological achievements in the biotechnological production of itaconic acid are presented. Particular attention is paid to current achievements in terms of suitable alternative substrates and their applicability in fermentation processes. Also, the pathway of itaconic acid and especially the influences on the fermentation process, which must be known in order to achieve a high final titer of itaconic acid, a yield close to the theoretical yield, and high productivity.
