A Rapid and Efficient Method for Plasmid Transformation of Klebsiella pneumoniae and Escherichia coli

SUMMARY: A rapid and efficient method for plasmid transformation of Klebsiella pneumoniae M5al and Escherichia coli K12 has been developed. The method, which uses a freeze-thaw cycle in the presence of CaCl2 to facilitate DNA uptake, is substantially more efficient for K. pneumoniae M5al than the conventional transformation procedure for E. coli. The simplicity and speed of the method makes it very attractive for routine transformation of K. pneumoniae M5al and E. coli K12.