Sterile Air Drying of DNA - (Sep/18/2012 )
Can someone tell me the best way to keep DNA pellets in microcentrifuge tubes (from DNA extraction) sterile while air drying them? Also, when drying out 70% ethanol from the pellet by air, can you tell me (roughly) how long this would take?
Why do you need to keep the DNA sterile? It's rarely necessary. The ethanol will evaporate after DNA is spun down and the supernatent removed after about 10 minutes if the tube is left open on the bench. You can tell if it is gone by smelling the tube.
Dry your pellets open in a tissue culture hood.
But I should say that none of your DNA extraction reagents were likely to be sterile, so I don't know how much you should really worry about this.
I routinely use DNA prepared with non sterile reagents and dried on the bench for both transformations and transactions and have never experienced a contamination from the DNA.
Also, if you remove almost all of the 70% ethanol by inverting the tube or with a pipette, so that the tube has no visible liquid (but the pellet is still wet), I would leave the pellet for an hour or so to completely dry. I do err on the side of caution though, so it may actually be dry much faster than this.
Ok, thank you for the responses. That helps a lot!
I want to keep things sterile because that will help prevent contamination with nucleases, but I'm also probably being a neurotic microbiologist
Thanks a ton!