Electroporation is widely used for highly efficient transformation of Saccharomyces cerevisiae. As many strains degenerate over time or over environmental exposure

their electroporation efficiencies could drop markedly by 2 to 3 orders of magnitude. Here we describe a modified electroporation procedure which included single stranded carrier DNA for electroporation as well as a postelectroporation growth period in YPD medium

which gave rise to 13 fold enhancement in transformations than an optimized lithium acetate (LiAc) and dithiothreitol (DTT) Pretreatment protocol previously reported. An enhancement of 114 fold on Pichia pastoris transformations has been observed using the modified procedure. The modified method enhanced the transformation efficiencies of some degenerated S. cerevisiae strains by nearly 100 fold. It will enable molecular manipulations in all kinds of S. cerevisiaeand P. pastoris strains by allowing propagations of all sorts of DNA libraries made from minute samples.