Using this kit, 250 ml of bacterial culture typically yields up to 600 ug of high quality DNA (though yields will depend on various factors like copy number, stability and size and host strain of the plasmid). This kit has almost no centrifugation step (only pelleting cells). The use of the QIAprecipitator, which is a filter that can be operated with a syringe makes the isopropanaol precipitation and ethanol wash step much easier.
This kit has 3 key features:
1. Color-coded buffers to ensure proper lysis and neutralization
2. Use of QIAprecipitator avoids the tedious step of centrifugation after isopropanol precipitation. Even the ethanol wash step is facilitated by use of a syringe. The QIAprecipitator also eliminates the danger of pellet loss.
3. The elimination of centrifugation makes the procedure extremely fast; transfection quality DNA can be obtained within an hour.
The initial steps of lysis and neutralization have been made far easier by using color coded buffers. On adding the lysis buffer, the solution should turn blue which indicates complete lysis. After adding neutralization buffer, the color returns to white; this helps to ensure proper mixing and complete precipitation of cellular debris – a crucial step in plasmid DNA purification.
The QIAfilter columns used in earlier kits are also used in this kit to clear the cellular debris and allow for good filtration of the precipitated material. They are simple gravity flow and so need no other equipment which makes this kit very attractive.
The best feature I found was the QIAprecipitator. After adding isopropanol to the DNA eluted from the maxi columns, you just need to pass it through another syringe-shaped column. After passing the isopropanol treated samples through QIAprecipitator, ethanol washes can be performed followed by elution with 1 ml of water or Tris buffer.
There are no lengthy incubations, no use of centrifuges and, therefore, no loss of the DNA pellet which is possible in traditional isopropanol precipitations.
I have used this kit for preparing plasmid DNA for transfection of mammalian cells. I have used this kit just once and liked it very much. I highly recommend this kit for all labs needing to perform large scale preparations of plasmid DNA.