Clonal selection and characterization of epigenetic variation in Pichia pastoris

Abstract

Recombinant proteins produced by different host organisms have been broadly used as therapeutics. Considering the demand for large quantities of protein drugs, methods are needed to increase reactor titers in a timely and cost-effective manner. We used random chemical mutagenesis to modify a wild-type strain of the heterologous protein production host Pichia pastoris, which resulted in overall improvement of the secretion rate of the mutated population. More than 4000 single-cells were simultaneously screened for high secretion of a human Fc fragment using microengraving and the top-producing clones were retrieved. Future characterization of these improved clones by transcript profiling should yield information about networks of genes central in heterologous protein secretion in the yeast P. pastoris.