Microbiology List: FW: plating efficiency

gerne at my-deja.com gerne at my-deja.com
Tue Jan 16 17:32:17 EST 2001


for a better understanding of the problems with counting and viability
you might want to look at the special issue of the journal of
microbiological methods available for free at
http://www.elsevier.com/locate/jmicmeth

As you can see in the article of the functional assessment of bacteria,
the correllation between what is in your sample and what will grow on a
plate becomes poor when your cells are not perfectly happy any more.

If you want to get a simple flow cytometer for bacterial counting you
might want to look at
http://www.optoflow.com/

As a practical tip you might want to treat flagellated organisms in a
sonicator waterbath to shear off the flagella and have the holding
still better for the counting.

With kind regards
Gerhard Nebe-von-Caron


In article <1523-3A578563-46 at storefull-114.iap.bryant.webtv.net>,
  nmaccallister at webtv.net (Neil MacCallister) wrote:
> Thank you for this information,..it seems you prefer the light
> microscope for truly accurate counts,and that is reasonable,
especially
> if you can differentiate "out" the non-viables with a stain. I know
that
> even the Gram-stain prefers
> "actively growing bacteria"..(giving some protection in that regard,
> especially for gram +'s)..Which stain do you use for active ribosomal
> marking..(sorry, I'm no expert here!)?
> Will that stain mark after heat-fixing?..or better yet, will it, or
> another,...mark the cell while it is growing in a broth, so that it
> might be immediately transferred to a counting chamber
(Petroff-Hauser)
> and physically counted? Wouldn't that be the greatest!?..(2 drops of
> stain,..transfer to chamber,..and count!)
>
> More questions?..Sure!: Does a phase contrast microscope adequately
> remove the need for any stain when counting a broth culture in
> chamber?...(The "set up",..of good quality phase-contrast microscope
and
> P-H counting chamber,..would cost about 6-7K,..but would be worth it
if
> it reduced the time/improved the accuracy of counts in solution,..and
> that's why I ask.)
> ..........Thank you,..and your statements regarding e.coli counting
> were also of interest.
>                       ..Lastly,.."Happy New Year!"
>
>


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