JM109 Competent Cells

JM109 competent cells are a classic E. coli strain for routine cloning and plasmid maintenance. E. coli K12 JM109 is recombination- and endonuclease-deficient, improving insert stability and quality of miniprep DNA, respectively. The hsdR mutation prevents the cleavage of cloned DNA by the EcoK endonuclease system.