Economical method for midiprep plasmid DNA purification using diatomaceous earth

Diatomaceous earth has been used for DNA purification as it can produce high quality plasmid DNA. We describe an alternative and economical method for plasmid DNA purification from a 50-ml bacterial culture using diatomaceous earth, plastic pipette tips, conical tubes, centrifuges, and without requiring a vacuum system. Depending on the plasmid size and the origin of replication, this method yielded 200-800 mu g plasmids with an A(260)/A(280) of 1.8-2.0. These purified plasmids are suitable for many applications such as DNA sequencing and transfection experiments.