Fig. 2

Profiles of cell growth, glucose consumption, and astaxanthin production of X. dendrorhous in the 5-L bioreactor. A Control group; B Na-citrate group. During the fermentation process, the temperature was maintained at 22 °C, the ventilation rate was 2 vvm, and the stirring speed was amplified step by step (0–24 h, 200 rpm; 24–48 h, 300 rpm; 48–72 h, 400 rpm; 72–120 h, 500 rpm), and the dissolved oxygen (DO) was maintained at more than 30% by the DO cascade. Glucose (open square), biomass (filled square), carotenoid titer (filled triangle), astaxanthin titer (open triangle), and astaxanthin content (open circle). The data shown are the average of two replicates (± standard deviation)