Abstract

Process techniques of the methylotrophic yeast Pichia pastoris for the production and recovery of heterologous phytase proteins has developed in last 20 years. High expression levels using methanol as induction have been made in the quality of recombinant proteins in the fermenter culture and in the quality of the protein product. This allowed rapidly P. pastoris to become the system of choice for the expression of recombinant proteins in yeast. The experimental designs, the methanol/L-alanine co-feeding strategy and optimization of phytase production by P. pastoris supported by the optimum levels of variables and lower temperature expression produced high level of phytase activity which could be scaled up to produce phytase for food additives at industrial level.  An overall phytase activity was 8632 U/ml, this means 332 fold increase compare to the wild type of phytase. This work demonstrates not only the impact of α-factor prepro secretion signal and efficiency of methanol/L-alanine co-induction strategy for phytase production by recombinant P. pastoris Mut⁺ strains, but also shows new insights for the expression of bioproduct at lower temperature.

Key words: Phytase, gene expression, Pichia pastoris, process optimization, co-feeding strategy, Deglycosylation.