P47: Animal-free media optimization for recombinant protein production in Pichia pastoris

It has been our experience that many process scientists screen raw material components individually, particularly in the case of yeast extracts and protein hydrolysates.  However, in our microbial applications laboratory, it has been determined that to fully explore the potential of peptones and yeast extracts it is essential to co-test them, taking into account possible interactions and/or synergies.

Pichia pastoris is an industrial methylotrophic yeast that represents one of the most effective and versatile systems for the production of recombinant proteins. Pichia pastoris is capable of growing in both complex and synthetic media. However, complex media can have certain advantages with regard to both biomass and protein production/quality.

In recent years there has been a growing trend towards the use of non-animal media components. This relates to a number of issues that have arisen including the mycoplasma contamination in the 1970’s, endotoxin issues in the 80’s and BSE scares in the 90’s. Following this trend the primary focus of our lab is optimizing non-animal complex media formulations that will contribute to an increase in biomass and/or protein production/quality in Pichia pastoris fermentations.

In this study a number commercially available Pichia pastoris host strains were pre-screened for growth response to 70 of Sheffield’s unique animal component free total nitrogen sources designed to replace both yeast extracts and peptones.  The most successful media from the pre-screening growth studies were then analyzed with regard to their ability to promote protein expression in a number of Pichia strains.