Osmotic shock?

M. Alexeyev malexeyev at biost1.thi.tmc.edu
Tue Nov 7 10:02:40 EST 1995


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 would 
> >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.

M.A.



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