yeast cell counts

Tim [iso-8859-1] Söllick soellick at
Tue Feb 15 10:27:29 EST 2000

Dear Suzanne,

in my opinion there is never a compare culture density for yeast, because cells
clump and
therefore never a culture of one yeast strain is comparable to another. Even one
yeast strain is
not comparable to a second bath of this strain if it is transformed with same
kind of strange vector.

So my suggestion:

Do count your cells ! Use a hemocytometre (Fuchs-Rosenthal-chamber) and dilute
your culture 1:10
and 1:20. Count five small squares of each dilution. I normally find that then
the cell counts are comparable.

A normal over-night cultures gives then about 1 - 2 x 10e7 cell/mls.

Good luck.


Suzanne Schulz wrote:

> We are have a basic question about yeast cell counts.  I have been
> reading the A600 of yeast cultures to determine approximate cell
> numbers. I usually dilute the cells 1:10 to keep the absorbance between
> 0.1 and 1.0 as I assumed this was a linear function.  I recently noticed
> that a 1:20 dilution gave an A600 of 1.0 so this = 20 OD/ml. But the
> same culture diluted 1:40 had an A600 = .65, so multiply x 40 = 26
> OD/ml. The more I dilute the culture and more cells I have. How can I
> accurately compare culture densities??

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