Metabolic Model And Oxygen Transfer Model In Recombinant Pichia Pastoris Cultivation

The Pichia pastoris expression system has been increasingly employed both in academic and industrial biotechnology for the production of various recombinant heterologous proteins. In this thesis, we use Pichia pastoris expressing recombinant human serum albumin (rHSA) as a model system to study the following contents:Metabolic model for Pichia pastorisA metabolic model for Pichia pastoris expressing rHSA is proposed. The model describes the balances of some key metabolites, ATP, NADH and FADH2 during glycerol and methanol metabolism. Based on the model, the metabolic bioreaction rates such as the specific substrate consumption rate, the specific growth rate, the specific acetyl-CoA formation rate as well as the specific oxygen uptake rate are obtained. The specific substrate consumption rates and the specific growth rate are then coupled into a bioreactor model such that the relationship between substrate feeding rates and the main state variables, i.e., the medium volume, the concentrations of the biomass, the substrate and the product, is set up. Experimental results demonstrate that the model can describe the cell growth and the protein production with reasonable accuracy.Oxygen transfer model for Pichia pastoris cultivationAn oxygen transfer model is established for recombinant Pichia pastoris cultivation carried out in a stirred tank bioreactor. The model takes agitation speed, aeration rate, dissolved oxygen concentration, medium volume and medium...