Osmotic shock?

Andrew Gumley awgumley at sciborg.uwaterloo.ca
Wed Nov 8 15:57:29 EST 1995

In article <malexeyev-0711951005330001 at>,
   malexeyev at biost1.thi.tmc.edu (M. Alexeyev) wrote:
>In article <47n8ea$gr1 at mo6.rc.tudelft.nl>, Lesley Robertson
><L.A.Robertson at stm.tudelft.nl> wrote:
>> awgumley at sciborg.uwaterloo.ca (Andrew Gumley) wrote:
>> >Does anyone know what effect transfering bacteria, specifically a 
>> >Gram-negative, to sterilized water would have on the physiology.  How 
>> >the bacterium componsate from such an osmotic stress.
>> >
>> >Thanks,
>> >
>> >
>> >Andrew
>> >
>> >awgumley at sciborg.uwaterloo.ca 
>> They burst.
>> Lesley Robertson
>Not necessarily (I think). I recall being surprised when I met in one
>article (sorry, I don't have a reference handy) the statement that authors
>used sterile water for diluting the cells for plating after conjugation. I
>am pretty much sure that strain was Gram-negative. Many people dilute
>their cells in 10 mM MgSO4, which is not an isotonic solution (neither it
>is a distilled water, thought).  I've done some E.coli dilutions in dH2O
>without significant loss in the titer (there were no side-by-side
>controls, though). Finally, they use an osmotic shock to release
>periplasmic proteins expressed in E. coli with low (or no) contamination
>with cytoplasmic proteins (and, I may add, in some cases it takes more
>than just dH2O to release periplasmic proteins efficiently). I understand
>that none of the above can be considered a direct evidence, but I wouldn't
>make an across-the-border statement about cells bursting.

Actually, I have transferred Gram-negative bacteria to dH20 and have left them 
for over 20 days AT 25oC.  There was no evidence of cell lysis and infact 2-D 
SDS-PAGE reveal the production of numerous proteins not observed in the 
control culture (before transfer).  It is speculated that these proteins may 
be involved in adapting the bacterium to the hypo osmotic environment.  
What I really wanted to know is what physiological adaptations could occur to 
allow the bacterium to survive such a stress.

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