A general method for polyethylene-glycol-induced genetic transformation of bacteria and yeast

Polyethylene glycol (PEG) can induce genetic transformation in both bacteria (Escherichia coli) and yeast (Saccharomyces cerevisiae) without cell wall removal. PEG-mediated transformation of E. coli is technically simple and yields transformants with an efficiency of 106–107 transformants/μg DNA. Detailed analysis of the parameters involved in PEG-mediated transformation of E. coli reveals basic differences between the PEG and standard CaCl2 methods for transformation of E. coli. PEG-mediated transformation of yeast is far simpler than existing protoplast methods and is comparable in efficiency. The new methods described here for PEG-mediated genetic transformation may prove to be of general utility in performing genetic transformation in a wide variety of organisms.