Fig. 9

Influence of pH control versus pH buffer on P. vulgatus in benchtop fermenter cultivations. Online and offline profiles of P. vulgatus cultivations with pH control at pH 7.0 (solid lines and filled symbols) or with 50 mM MOPS buffer (dashed lines and blank symbols, data from Fig. 8). Medium = DMMG, c_Glucose = 6 g L⁻¹, T = 37 °C, n = 600 rpm, V_L = 1500 mL, vvm = 0.2 min⁻¹, gas mix = 1% CO₂, and 99% N₂. After 6 h, 0.5 mL of antifoam was added to the bioreactors. Online and offline data of a carbon dioxide transfer rate (CTR) and osmolality; b online pH (green lines), OD_{600 nm} (red squares), total acids (blue stars), and base consumption (turquoise line); c glucose (pink diamonds) and lactate (orange triangles) concentrations; d succinate (brown triangles), acetate (purple triangles), formate (light blue triangles), and propionate (dark blue pentagons) concentrations. The vertical dotted line refer to the pH-controlled fermentation and marks the time of the glucose depletion. e–f Molar carbon balance in % of the initial carbon, calculated with Eqs. 3-5. Initial values include acids from preculture