Rapid transfer of low copy-number episomal plasmids from Saccharomyces cerevisiae to Escherichia coli by electroporation.

A simple and reproducible method for transferring low copy-number episomal plasmids from yeast to Escherichia coli has been developed. Although slightly more time-consuming than direct transfer methods, which are effective with high copy number plasmids, the method is significantly faster than methods that require purification of yeast DNA. Plasmid DNA is released from yeast cells during brief treatments involving grinding with glass beads and heating. The treated yeast are cooled, electrocompetent E. coli is added, the mixture is electroporated, and transformants are selected using standard conditions for E. coli electrotransformation. The procedure typically yields sufficient transformants for most applications.