[Microbiology] Re: I don't know why!!!

Tom McCloud via microbio%40net.bio.net (by mccloud-tom from worldnet.att.net)
Mon Jun 18 18:07:56 EST 2007


You also may be want to use higher glycerol concentrations (we are 
using  about 40 % glycerol for 30 years) preventing freezing of the 
glycerol and cells when storing in the  minus 20-25oC freezer. (Of 
advantage when taking  frequently samples form the "frozen" stock for 
inoculations) Yes, indeed,  as McCloud mentioned,  a too slow freezing
at minus 80 can reduce drastically the survival. Also important is to 
allow the cells to equilibrate with the glycerol before starting to
freeze.  Juergen Wiegel


On Wed, 13 Jun 2007 03:07:56 GMT, Tom McCloud
<mccloud-tom from worldnet.att.net> wrote:

>On Mon, 11 Jun 2007 11:21:37 -0000, tuffwave <tuffwave from gmail.com>
>wrote:
>>I'm working about lactic acid bacteria.
>>I used 20% glycerol+20% glucose solution for preventing the damage by
>>freezing.
>>In lab-scale, this process is normal.
>>But when this process is scale-up (250L main fermentation->suspension
>>using 15 L anti-freezing reagent), lactic acid bacteria was dead over
>>90%.
>>I don't know why cell death by scale-up was happened.
>>Help me!!!
>
>Not sure we have enough facts,  but what is the volume of the culture
>which has poor viability and what is the volume of the culture that
>maintains good viability?   Cell damage is generally least with quick
>freeze/quick thaw while there is greater cell damage with slow freeze
>slow thaw.   Could it be that your larger volume is freezing much more
>slowly and likewise defrosting much more slowly?  Tom McCloud


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