Efficient Development of a Mixed Feed Process for Pichia pastoris

Pichia pastoris is one of the most important host organisms for the recombinant production of proteins in industrial biotechnology. A prominent promoter system for recombinant protein production in P. pastoris is the promoter of alcohol oxidase (PAOX1) which is induced by methanol, but repressed by several other carbon sources, like glucose and glycerol. Thus, typical cultivation strategies for such P. pastoris strains describe two different phases: growth on a carbon source, like glycerol, to get a high biomass concentration, followed by the induction of recombinant protein production by methanol. However, cells barely grow on methanol resulting in only moderate productivity in such bioprocesses. To enhance productivity, it is common to employ mixed substrate feeding strategies. The knowledge of certain strain-specific parameters is required to be able to set up such mixed feed fed-batch cultivations to avoid methanol accumulation and guarantee highest productivity. Here, we present an efficient strategy comprising only one experiment to determine the settings of such a mixed feed system based on the physiology of the respective yeast strain.