Statistical Medium Optimization for the Increased Production of Recombinant Phytase in the Fed-Batch Cultivation of Pichia pastoris

Abstract

Abstract Using a 20-run central composite design, standard Basal Salt Media (BSM) was optimized for the production of recombinant phytase by Pichia pastoris in bioreactor-based fed-batch cultivations using glucose as the carbon source. The phytase activity in the supernatant of the cultures at the end of 48-hour runs was modeled as a function of the medium composition, and this model was successfully validated. Using Inductively Coupled Plasma spectroscopy (ICP), residual elements were quantified in the cultivation broth at the end of each run to confirm that differences in final cell density and enzyme activity were not due to nutrient depletion, but indeed associated with the variations in medium composition. The optimized media contains significantly lower concentration of the potassium and magnesium sources (28.7 g/l KH2PO4 and 4.8 g/l MgSO4·7H2O respectively), as well as a reduced concentration of trace salts, and based on experimental results, significantly outperforms standard media in terms of recombinant product yields under the same conditions.