Fig. 2

Characterization of abrupt OTR increases in the fed-batch phase at varied initial reservoir glucose concentrations with the membrane-based fed-batch shake flask. Depiction of a OTR; b glucose concentration in the culture medium; c ammonium concentration in the culture medium; d ammonium concentration in the reservoir; e pH in the culture medium; f cell dry weight; Cultivation conditions: Wilms-MOPS-mineral medium (culture medium: 200 mM MOPS with 7 g/L initial ammonium sulfate, initial reservoir glucose concentrations: 250/375/500/750 g/L, blue dextran concentration: 1 g/L, temperature: 37 °C, shaking frequency: 350 rpm, shaking diameter: 50 mm, initial culture medium volume: 10 mL, inoculation OD₆₀₀: 0.5, reservoir filling volume: 2 mL, dialysis membrane: Reichelt 10–20 kDa, membrane area: 18.1 mm²; Strain: E. coli BL21 (DE3) pRhotHi-2-EcFbFP; Concentration values have been volume-corrected; The arrows point to the occurrence of abrupt OTR increases