Glycerol stocks at -20?

m.a.jones mbi050 at
Fri Jun 30 05:40:44 EST 1995

MarkSmith wrote:
: In article <3ruri3$d6f at> vwarwar at (vitor warwar) writes:
: >
: >     Hi all:
: >
: >     Does anybody knows of bacteria glycerol stocks could be
: >     stored at -20 instead of -70?
: >
: >     Thanks,
: >
: >     Vitor
: >
: >--
: >______________________________________________________________________
: >     Vitor Warwar / 406 Plant Sciences Hall / University of Nebraska
: >     Lincoln NE 68593-0722 / USA / vwarwar at
: >_______________________________________________________________________

: Dear Vitor,
: DEpends on what bacteria you are talking about. We store E.coli in 40%
: glycerol at both -20C(for a few months) and at -80C(almost indefinitely).
: We store B.subtilis in 15% glycerol at -80C. -20C is no good for this
: organism.
: I suggest as a good all round way 15-20% glycerol at -80C.
: Regards
: Mark
: Mark Smith                      | The saying is sure and worthy of
: Dept. of Biochemistry           | full acceptance, that Christ Jesus
: University of Sydney            | came into the world to save sinners.
: Sydney, NSW, 2006               | And I am the foremost of sinners.
: Austraila                       | 
: m.smith at     | 1 Timothy 1:15

Just to add to the other reply you have had,
Rhizobium strains can normally be stored at -20oC as can E. coli, 
one of the factors which has a lot of bearing on how well your glycerol stocks
will survive is how often you let them thaw.

The best  method is not to let them thaw when you take strains from glycerol
stocks, but to scrape a tiny bit of the glycerol from the top of the vial while
it is still frozen. 

The first lab I was in kept all its Rhizobium and E. coli stocks in -20oC. 
The best policy with this is to have a Lab Stock which hardly ever leaves the
freezer and a working stock (made when a project is started) which can be use by
individual staff/students/postDocs etc..

The Lab I work in now stores strains at -70oC as pointed out this is preferable
if available, but not essential. The main ppoint is if a strain is so vital to
your work or Lab there should be more than one stock and -70oC is better.

-20oC is adequate for storage if you do not keep thawing samples. 

M A Jones 


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