Fig. 5

Kinetics of citrate production and d-glucose utilization on Mn²⁺-deficient- and Mn²⁺-sufficient media. Residual glucose content and citric acid production were monitored during controlled batch cultivations in fermentors. The initial concentration of d-glucose was 140 g L⁻¹. a The fermentation kinetics under Mn²⁺ deficiency (5 µg L⁻¹); b cultivations with sufficient Mn²⁺ (100 µg L⁻¹). Fermentations were carried out in triplicate, starting from conidiospore suspensions. The investigated strains are the dmtA deletion mutant (∆dmtA), the dmtA overexpressing mutant (dmtA^OE) and their parent NRRL 2270. Filled symbols represent d-glucose concentrations (●—NRRL2270, ■—∆dmtA, ▲—dmtA^OE); open symbols show citric acid concentrations (○—NRRL 2270, □—∆dmtA, ∆—dmtA^OE). Standard deviations are indicated with vertical bars for each determined concentration. Note that in the cultivations under Mn²⁺ limiting conditions (panel a), the bar is sometimes smaller than the symbol that marks the mean citric acid medium concentration