New insight into the method of posttransformational vector amplification (PTVA) in Pichia pastoris

Posttransformational vector amplification (PTVA) is widely used to enrich the gene-copy number in Pichia pastoris. We engineered two test strains for PTVA studies and demonstrate that the PTVA process results in the amplification of a fragment with the resistant gene flanked by two homologous arms instead of the entire vector.