Storage ofEscherichia coliStrains Containing Plasmid DNA in Liquid Nitrogen

摘要

The stability of plasmids and lysogenic bacteriophage in 16 strains ofEscherichia coliwas studied following storage in liquid nitrogen for periods up to 2 years. A comparison was made with cultures which had undergone lyophilization. Plasmid loss was detected by plating on selective media containing antibiotics to which resistance was conferred by plasmid DNA. Loss of plasmid DNA was not evident following storage in liquid nitrogen or lyophilization.