Itaconic Acid Production by Ustilago maydis

This thesis endorses the establishment of U. maydis as an alternative whole cell biocatalyst for the biosynthesis of itaconate from renewable substrates, such as cellulose or hemicellulose. Therefore, the fungal family Ustilaginaceae was screened for their natural production of value added chemicals, such as itaconate, malate, or succinate, to identify potential novel natural biocatalysts and to find the best producers. The screening was facilitated by the development of a new medium composition (modified Tabuchi medium). In order to combine the utilization of raw biomass components, such as cellulose and hemicellulose, with the production of valuable platform chemicals, such as itaconate, the best itaconate producer, U. maydis MB215, was further characterized towards its xylan degradation ability and itaconate production. A novel biosynthesis pathway for itaconate was identified, including clustered genes encoding the proteins responsible for itaconate production in U. maydis MB215. First metabolic engineering attempts were already successful in enhancing U. maydis' itaconate production two-fold by overexpressing the transcription factor regulating the expression of the itaconate gene cluster. This work lays the foundation for further optimization of U. maydis' itaconate biosynthesis and is therefore a further step towards industrial application of the Ustilaginaceae for the advancement of a sustainable bio-based economy.