help storing yeast

tim stearns stearns at leland.Stanford.EDU
Mon Jul 11 12:00:04 EST 1994


In article <2vrmlb$8lu at riscsm.scripps.edu>,
Tedd Elich  <Elich at sc2.salk.edu> wrote:

>I've only been working with yeast (S. cerevisiae) for about a year now
>and I've noticed that my -80 stocks are losing a lot of viability with
>age (with some of my older stocks I can only get a few colonies from
>large scoops).  I prepare my stocks by adding an equal volume of 30%
>glycerol to an overnight culture, freezing in liq. N2, then transferring
>to -80.  Does anybody have any suggestions as to how to make stocks that
>last longer?  I would appreciate any help.  Thanks

There is almost universal agreement that rapid freezing in liquid N2
is bad for freezing cells in general.  Do exactly what you have been
doing but leave out the quick freeze step and your strains will
survive happily for decades in the -80.  We freeze yeast in 25%
glycerol, but others say that 15% is fine.   

Tim Stearns
stearns at leland.stanford.edu




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