GoldBio’s JM109 Chemically Competent E. coli cells are suitable for high efficiency transformation in a wide variety of routine applications such as plasmid isolation, library construction, cloning, and subcloning. JM109 is a K strain bacterium that carries multiple features including the lacIqZΔM15 marker, which provides α-complementation of the β-galactosidase gene with blue/white screening protocol as well as the hsdR17 genotype which prevents endogenous endonucleases from cleaving DNA.