Project description:Pichia pastoris is widely used as a host for recombinant protein production. More than 500 proteins have been expressed in the organism at a variety of cultivation scales, from small shake flasks to large bioreactors. Large-scale fermentation strategies typically employ chemically-defined growth media because of its greater batch-to-batch consistency and in many cases, lower cost compared to complex media. For biopharmaceuticals, defined growth media may also simplify downstream purification and regulatory documentation. Standard formulations of defined media for Pichia are minimal ones that lack the metabolic intermediates provided by complex components such as peptone and yeast extract. As a result, growth rates and per-cell productivities are significantly lower than in complex media. We have designed an improved defined media for Pichia pastoris, rich defined medium (RDM), by systematically evaluating nutrients of increasing complexity and identifying those that are most critical for growth. We have also demonstrated the use of RDM for expression of three heterologous proteins, at titers comparable to or higher than in standard complex medium. Rich defined medium has the potential to improve productivity of Pichia pastoris fermentations and accelerate process development for new molecules.
