Adaptive control of glycerol & methanol feeding in recombinant Pichia pastoris cultures: Impact on antibody titre

Pichia pastoris processes for heterolougous protein expression are typically run in three phases: a batch phase, an exponential feeding fed-batch phase and a long oxygen transfer limitation (OTL) phase. The final protein titre is often limited by the oxygen availability in the OTL phase. Here a direct adaptive controller is designed for the OTL phase. The controller was validated in pilot P. pastoris cultivations expressing a single chain antibody fragment (ScFv). This work shows that the proposed controller can regulate the dissolved oxygen tension (DOT) at very low levels (5 %) with high stability by manipulating the glycerol feeding rate, thereby enhancing the oxygen transfer at high cell density, which finally leads to a higher antibody titre.