Process engineering of Pichia pastoris cultivation for the production of a phytase with GAP promoter

Abstract

Pichia pastoris (P. pastoris) is a popular host for recombinant protein production. In this work, phytase production with P. pastoris under GAP promoter was studied. In the first part of this study, feasibility of using crude glycerol from biodiesel production as the sole carbon source for P. pastoris cultivation was investigated. Although growth inhibition was found in batch cultivations stated with high concentration of biodiesel glycerol, efficient high cell density production was realized by fed-batch cultivation started with a low concentration of biodiesel glycerol. The second part of this work focused on the study of growth kinetics with continuous cultivations under different dilution rates. The influences of dilution rate upon cell growth and phytase production were revealed and characterized with empirical equations. Based on these results, a simple kinetic model was established and model parameters were estimated mainly based on these results as well. Good agreement with experimental results was found when this model was applied to the prediction of cell growth and phytase production in regular fed-batch cultivation processes.