Fig. 4

High-density fed-batch fermentation at pH 5.0 with a prolonged feeding phase of U. cynodontis ITA MAX pH. Concentration of glucose (●), itaconate (■), pH (red line), OD₆₀₀ (▲) and ammonium (▼) during fermentation in a bioreactor containing batch medium with approximately 120 g L⁻¹ glucose and 75 mM NH₄Cl. Vessels with a total volume of 2.3 L and a working volume of 1.0 L were used. The pH was controlled by automatic titration with 5 M NaOH. After approximately 48 h, the pH was adjusted to pH 5 and afterwards maintained at this value until the end of the fermentation. Cultures were fed with an additional 540 g glucose (70% w/v feeding solution) at rates between 0.25 and 2.2 g h⁻¹ (32–648 h). The feeding profile is shown in Additional file 2. The feeding rates were manually adjusted in order to maintain the glucose concentration at a constant level of approximately 50 g L⁻¹. The mean values with standard deviation of two independent biological replicates are shown