high pressure sterilization

mccardaj at esvx23.es.dupont.com mccardaj at esvx23.es.dupont.com
Thu Sep 29 08:54:09 EST 1994


In article <35v2vd$7pv at alf.uib.no>, Kjell Magne Fagerbakke writes:
>In article <1994Sep22.133837.18968 at es.dupont.com> mccardaj at esvx17.es.dupont.com writes:

Main point from previous article:

>>I am doing some work using high pressure with ambient temperature for sterilizatliz
>>ation purposes.  Does anyone know how high pressure kills bacteria?
>>
>>My original thought was that the water within t
>>I would appreciate any discussion on the mechanism and of course if
>>anyone has any good references/review articles to suggest I would be
>>grateful.  I am totally new to this field and could definitely use some
>>advice.
>>
>>Thanks,
>>A.J. McCardell
>
>
>I am not familiar to high pressure sterilization, and I find it 
>as a  strange way of doing it. Bacteria is found at deep depths 
>of the ocean so I recon they may survive 4-500 atm. Water is not 
>a medium that will compress much. Think I read somewere (to long 
>ago so I can't give a reference) that bacteria live as usual when 
>you put pressure on them. I have also experinced that a "french 
>press" not were enough to kill a culture of cyanobacteria.
>
>Any osmotic stress may in my oppinion be to small to kill the cells
>and may be ignored.
>
>The most crucial step I think must be the drop in presure. 
>Gasses (if any) will expand enourmously and this shoud be real
>effective (I stress if any).
>
>Dead cells may also be turbid I guess. 
>
>Kjell Magne Fagerbakke
>University of Bergen, Norway


High pressure sterilization is used in cases where the traditional means of steri
sterilization are not amenable to the item being sterilized, such as something
that would melt at high temps in an autoclave.  I also know of some work using h
high pressure to sterilize certain foods, such as fruit to be put into yogurt.

Please could someone explain to me what a "french press" is?  This is the 
second reference to it and I have no idea what this is.

I like your idea about the most crucial step being the drop in pressure.  

Yes, dead cells can be turbid too, but not lysed ones?  My point was that I
was expecting the cell to be lysed and therefore the suspension clear.  

We have had a fair amount of success to date with everything but those nasty sp
spores, specifically Bacillus stearothermophilus.  

I am still hoping to generate more discussion on how high pressure affects the 
bacteria.  By what mechanism(s) does it actually kill cells?




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