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Natural Science Forum / Biology / Microbiology / June 2007I don't know why!!!
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!!! >I'm working about lactic acid bacteria. >I used 20% glycerol+20% glucose solution for preventing the damage by [quoted text clipped - 5 lines] >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 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 >>I'm working about lactic acid bacteria. >>I used 20% glycerol+20% glucose solution for preventing the damage by [quoted text clipped - 12 lines] >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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