Glycerol in Freezing media

David R. Boone boone at
Wed Sep 25 09:57:29 EST 1996

I'm not sure I can give the reason for this, but glycerol often increases
the recovery of bacteria after freezing.  I curate a culture collection
that uses 5% glycerol in cell suspensions for freezing.  Some bacteria
freeze very well under any circumstances.  Others, especially those
without peptidoglycan cell walls, give very poor recoveries unless
glycerol (or some other cryoprotectant) is present and unless the freezing
rate is controlled at about 1ºC/min.  These two factors can increase the
recovery by 5 to 6 orders of magnitude for some strains.

David R. Boone
Professor of Environmental Microbiology
Oregon Graduate Institute, Portland
(503) 690-1146

> Louis Geller <bbbbd at> wrote in article
<3248D5D3.4F9A at>...
> Hi.
> 	I was wondering exactly it is necessary to have glycerol in freezing
> medium for bacteria, yeast, and animal cells.
> 	Exactly how does the glycerol protect the cells?
> 	Thanks in advance,
> 	Louis Geller...
> 	lgeller at
> 	bbbbd at

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