Take 1 - 5 ml of overnight bacteria culture and lyse the cells by an optimized SDS-alkaline method. With this kit, the extraction of multiple samples can be completed within 30 min without involving phenol-chloroform extraction or ethanol precipitation. The kit uses a unique spin column to specifically bind plasmid DNA in the solution in a highly efficient manner under high-salt and low-pH conditions and remove proteins, genomic DNA, RNA, and other impurities to the greatest extent. In the end, pure plasmid DNA is eluted from the silica membrane with a low-salt, high-pH eluent. Each column adsorbs up to 35 µg of plasmid DNA. The purified plasmid DNA is ready for use in biological experiments such as enzyme digestion, PCR, sequencing, ligation, transformation, transfection, and common passaging cells experiments.