Fig. 1

Fermentation of Ustilago trichophora TZ1 with different NH₄Cl concentrations. a OD₆₀₀, b malate production, c maximum malate production rate (solid bars) and yield (open bars) for controlled batch fermentations in MTM containing 200 g L⁻¹ initial glycerol at 30 °C and pH 6.5 with DO kept at 80 %. Colors indicate different initial NH₄Cl concentrations: 0.8 g L⁻¹ (circles, blue), 1.6 g L⁻¹ (diamonds, green), 3.2 g L⁻¹ (squares, red), and 6.4 g L⁻¹ with doubled concentrations of all medium components except glycerol (triangles, black). Values for 0.8 g L⁻¹ are only shown until 432 h; however, a further increase in concentration to a final titer of 120 ± 1 g L⁻¹ could be observed until 908 h of cultivation. Error bars indicate deviation from the mean (n = 2)