On 25 Mar 1999, Brendan Scott wrote:
> My lab is currently debating the pros & cons of what temperature is best
> for storing DNA over the long-term ie 10 years, etc.. It has been
> suggested that storing DNA at -20C is bad, because if it is in a salt
> solution e.g. TE, it will undergo a constant freeze-thaw cycle that will
> break up the DNA. Manuals recommend 4C, but never say why. While 4C has
> worked in the past, there is a tendency for a minority of DNA samples to
> grow fungi, bacteria and other colonies of lifeforms - which, contamination
> aside, will presumably be producing working nucleases as well.
Why not precipitate the DNA on ethanol and store it at -20C? No
freeze/thaw worries - it stays in the same phase, inhibits the activity of
DNAses, and and uninvited life forms.