Fig. 2

Kinetics of propionic acid fermentations by P. acidipropionici from the different experiments conducted in the current study. a Specific growth rate (1/h), b PA maximum titers (g/L), c overall productivities (g/L h), and d yields (g PA/g sugars) from all of the fermentations conducted in this work. Color blocks highlight different experiments: (1) effect of CO₂ and N₂ on PA production in mock DDAPH substrates, (2) effect of different initial DDAPH concentrations on PA production, (3) effect of different nitrogen sources and pH control reagents on PA production, (4) evaluation of PA production in different fed-batch modes and feeding media, and (5) fed-batch fermentation with high cell density. YE, yeast extract; Control, YE + TSB; LYE-PF, 13.9 g/L YE in feeding medium and pulsed feeding; HYE-PF, 86.8 g/L YE in feeding medium and pulsed feeding; HYE-CF, 86.8 g/L YE in feeding medium and continuous feeding; HCD, high cell density