Over the past several months I have used Promega’s Wizard Plus SV Minipreps on an almost daily basis. During this period of time I have found that this kit is easy to use and extremely rapid, taking only 35-45 minutes from start to finish. Perhaps the best feature is its price – it is relatively inexpensive at a little less than a dollar a prep. The DNA that I have isolated using this kit has always been clean and one avoids the use of phenol and eliminates the lengthy ethanol precipitation and wash typical of standard plasmid purification protocols.
Originally, I began using this kit because, in addition to purifying DNA from standard laboratory E. coli strains that are usually endA-minus, I need to purify plasmids from Salmonella typhimurium. My previous experience with using other plasmid purification kits to isolate plasmids from S. typhimurium found that most were not suitable. This is possibly due to nucleases that “survived” the spin columns. This does not seem to be a problem with the Wizard kits. With the addition of the alkaline protease supplied in the kit, my DNA samples are stable in the freezer for long periods of time, even if stored in water (also supplied in the kit) and not TE.
The quality of plasmid DNA that I have obtained using this kit has been good. I have used the DNA for sequencing, primarily automated sequencing, and have not had any problems. High copy plasmids eluted in water can be used directly for automated (i.e. BigDye) sequencing and very low copy plasmids can be precipitated and concentrated (in about 30 minutes) prior to sequencing. I have had some problems with very large plasmids and cosmids, especially if they have low copy numbers, in terms of yields. But in these cases, culture volumes can be adjusted up to 5 ml in order to increase yields for some plasmids (the standard is 1.5 ml) and sufficient amounts of DNA are purified for cloning.
Overall I would have to say that the Wizard Plus SV Miniprep Kit is a good buy. It is relatively inexpensive, easy to use and yields good quality DNA. There is not much more that I look for in a plasmid purification kit.
Heran Darwin, Ph.D.
Postdoctoral Fellow
Molecular Microbiology
Washington University School of Medicine