Figure 2.

Two-phase fed-batch cultivation of P. pastoris X-33 carrying the AOX1 promoter-driven IP gene. Cells were first grown in a batch phase with glycerol as carbon source followed by a methanol feeding phase to induce the production of IP. (A) Concentrations of glycerol (filled squares) and biomass (optical density: filled circles; CDM: filled triangles). (B) Concentration of methanol (solid line) and amount of methanol added to the bioreactor (dashed line). (C) Medium pH (solid line), amount of ammonium hydroxide (dashed line), and amount of phosphoric acid added to the bioreactor (dotted line). (D) Dissolved oxygen concentration (solid line), aeration rate (dotted line), and stirrer speed (dashed line). (E) Oxygen transfer (dashed line) and carbon dioxide evolution (solid line) rates and respiratory quotient (dotted line). Arrows indicate removal of culture broth. (F) Cell growth (filled circles) and accumulation of IP (filled squares). The dashed vertical line indicates the end of the glycerol batch and the start of the methanol feeding phase.