high pressure sterilization
Fri Sep 23 12:23:57 EST 1994
In article <1994Sep22.133837.18968 at es.dupont.com> mccardaj at esvx17.es.dupont.com writes:
>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 the cell is highly compressed and then when the pressure is brought back down to atmospheri
>and then when the pressure is brought back down to atmospheric, it expands
>with a great deal of energy tearing apart the cell.
>I also thought that the cell may be under some osmotic stress. Also,
>what about the water undergoing a phase change at high pressure and thus
>acting like a non-polar solvent?
>My observations have been that after high pressure treatment, the turbid
>innoculum still appears turbid. I would expect a clearing of the innoculum
>if the cells had actually been lysed. I have not looked at the cells under
>a scope yet but plan to after our next run.
>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
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
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