freeze drying

Yjgent yjgent at aol.com
Fri Oct 27 10:38:50 EST 2000


> am about to commence freeze drying cultures of Bifidobacterium, and as
>I have never attempted to do this before, I am unsure as to what to do.
>Any advice, eg the addition of skim milk powder etc, will be gratefully
>received.

Lynn,
	I haven't used the freeze dryer in many years and always had problems with
viability. We used a 20% sucrose solution for most organisms, but I didn't work
with anaerobes at the time so I don't know any specific problems with them.
	The procedure we used was to put 1ml of organism/sucrose suspension in the
freezer vials and put them in the -70C freezer while we get the freeze dryer
set up. Once the freezer gets to the correct temp we take the tray of vials out
of the ultra freezer and put them in the chamber with the rubber stoppers on
the vials but not pushed down (don't seal the vials). Run the vacuum until
there is no moisture left - it all depends on the total volume (10 vials = 10
ml). Our set up had a "capper" that inflated a rubber bladder that pushed down
on all the stoppers while under vacuum. As soon as they are sealed you can
start to release the vacuum and take the vials out.
	We turned in our freeze dryer a couple of years ago when we lost a lot of our
services - mycology, parasitology and mycobacteriology. What I've done instead
was to go to a 15% glycerine in TSB solution and just freeze 1ML aliquots of an
organism suspension. I found that it works for most of my common organisms
including aerobes, anaerobes and some yeast. To retrieve these organisms just
scrape out some ice crystals and smear on a non selective media. Don't let it
thaw.

Hope this helps.
John Gentile M(ASCP)                   President - Rhode Island Apple Group
yjgent at aol.com
Microbiologists do it with culture.






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