Fig. 4

Effect of oxygen limitation on batch fermentation of Yarrowia lipolytica in unlimited and nitrogen-limited media. 20 h after inoculation aeration was reduced in unlimited (a and b) or nitrogen-limited media (c and d), resulting in a decrease of dissolved oxygen from 50 % (dO₂50) to 1 % (dO₂1) of saturation. In unlimited media, the highest accumulation of lipid was observed 36 h after reducing the air flow, resulting in ca. 110 mg TAG gDW⁻¹ (a). Glucose uptake and biomass production was significantly lowered and no citrate was produced (b). Combination of nitrogen and oxygen limitation resulted in 67 % higher lipid content (c) and in reduced citrate production (d), as compared to fully aerated nitrogen-limited media