[Enhancing expression efficiency of alkaline polygalacturonate lyase by constant cell concentration culture of the recombinant Pichia pastoris]

Abstract

In order to enhance the alkaline polygalacturonate lyase (PGL) productivity by Pichia pastoris, we developed a constant cell concentration culture strategy by methanol feeding (called as CCCM culture) used in the continuous cultures. We controlled reasonable cell concentrations in the bioprocess by different strategies of methanol feeding. Using this CCCM culture with DCW 75 g/L, we significantly enhanced the PGL productivity (Qv) and the average specific enzyme production rate (Qx) of PGL to 6.11 U/(mL x h) and 81.5 U/(g x h), increased by 42.1% and 191.2% than the fed-batch culture with high cell density, respectively. The final PGL activity was 441.9 U/mL. Moreover, the extracellular protease concentration is 1.9 mg/L and the cell viability is more than 94% after 120 hour induction. The results show that this new strategy is advantageous in reducing proteolytic degradation and enhancing cell viability.