The aim of this thesis was to establish a process for organic acid production, to valorize the crude glycerol stream from biodiesel production. Screening 126 Ustilaginaceae, resulted in Ustilago trichophora for malate and U. vetiveriae for itaconate production. Production values of both strains were improved in iterative steps. The reached production values strengthen the applicability of Ustilaginaceae to valorize crude glycerol. By this, the overall biodiesel bio‑refinery concept is improved.weiterlesen