Plasmid Miniprep Kit From Qiagen

The Qiagen Plasmid Miniprep Kit is an efficient tool for providing small scale, high quality, purified plasmid DNA for various applications, like transfection, gene silencing, cloning, sequencing and in vitro transcription. Like other Qiagen DNA purification kits, the plasmid mini kit is based on an alkaline lysis procedure, followed by purification of DNA on an anion-exchange resin column. Using this kit, 3-5 ml of bacterial culture yields 10-15 ƒÝg of purified plasmid DNA. The kit does not require many of the toxic reagents associated with traditional methods of plasmid DNA purification, such as phenol, chloroform and ethidium bromide, thus minimizing health hazards both to the user and the environment.

The initial steps of lysis and neutralization involve color coded buffers, where upon adding the lysis buffer, the solution turns blue indicating complete lysis. After addition of neutralization buffer, the color should return to white; this helps to ensure complete precipitation of cellular debris and genomic DNA. The cellular debris is removed by high-speed centrifugation and the filtrate is passed over a Qiagen-tip column. The column is then washed and the bound DNA is eluted with high salt buffer and precipitated with isopropanol. The process of DNA binding, washing and elution can be performed using benchtop centrifuge. The precipitated DNA is washed with ethanol, air dried and suspended in 20-25 ƒÝl of water or Tris buffer. Pre-packed QIAGEN-tip columns can be operated either by gravity flow or in centrifugation and never run dry, thus minimizing the hands-on time required for plasmid preparation. The entire purification procedure can easily be completed in 1 hour.

The kit is a very handy tool for screening recombinant clones and preparing DNA for both manual and automated sequencing. I have been using this kit for more than 8 years and am absolutely satisfied with the results. The quality of purified plasmids is very high and now I am using the purified DNA for in vitro transcription-translation reactions.