AN EFFICIENT METHOD FOR LARGE-SCALE ISOLATION OF PLASMID DNAS BY HEAT-ALKALI CO-DENATURATION

A method is presented for efficient and large-scale isolation of plasmid DNAs from bacterial cells. Based on the cooperativity of heat and alkali actions, the method provides DNA preparations with high quality and yield (about 2 mu g of DNA/ml culture), which are completely digestable by restriction enzymes and have a high transformation efficiency. Furthermore, the DNA preparations are extremely stable, and even through 4-year storage at -20 degrees C, the electrophorogram and transformation efficiency remain as high as before. The factors affecting the stability of various DNA samples are discussed.