Optimization of culture medium for large-scale production of heterologous proteins in Pichia pastoris to be used in nanoscience and other biotechnological fields

Abstract

The methylotrophic yeast Pichia pastoris became an excellent and successfully expression system for therapeutics and other useful heterologous proteins at large-scale. Its capacity to reach a high-cell-densityconcentration during its fed-batch fermentations in a chemically-defined culture medium is one of the main features of this system. The standard culture medium BSM developed by Invitrogen Co. has been the most widespread used. However, it contains certain components in improper ratios that lead to precipitation of some of its components during preparation, mainly after sterilization and/or during pH adjustment. In this study, we propose a modified version of the BSM culture medium, named MBSM. These simple modifications by employing a linear optimization technique solves the precipitation problems observed on BSM and other culture media. Beside it, is rather simple, easy to prepare, and inexpensive, and it has impact positively over the environment by reducing the pollution load of the fermentation waste and also diminish the cost of the industrial scale fermentation process. By using this modified medium, were reached cell densities of 100 gDCW · L-1 and 60 gDCW · L-1 for mini-proinsulin and exo-levanase under the inducible AOX1 and the constitutive GAPDH promoters, respectively. These results allow to get vast amounts of proteins able to be used in nanoscience and other biotechnological applications.