mass of bacteria

Michael Witty mw132 at
Thu Apr 4 09:25:38 EST 2002

On Thu, 4 Apr 2002, Colin A. B. Davidson wrote:

> "Michael Witty" <mw132 at> wrote in message
> news:Pine.SGI.4.33.0204041446020.5518869-100000 at
> > . . . or you can do an experiment.  Grow 100ml E. coli stationary phase
> > culture.  Take a small sample and count the cells (microscope or serial
> > dilutions).  Centrifuge the rest (tared tube).  Weigh the cells.  Divide
> > weight by number of cells.  Depends if you want to suffer from
> > having to make assumptions or from experimental error!  Mike.
> Surely, though, you're going to have a problem with this because you've got
> all of the water between the cells in the pellet? Although centrifugation
> gets rid of a lot of moisture, it doesn't get rid of all of it.
> Of course you could get round this by working out the dry mass of the cells,
> by doing exactly the same as is suggested above, freeze the pellet and
> lyophilise.

     yes you are right.  Far from perfect.  But an experiment is married
to the real world.  Sitting in an office and making assumptions is how to
get divorced from the real world!  Mike.

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