[Microbiology] Re: Measuring Rhizobium growth

Bob bbx107.XYZ at excite.XYZ.com
Mon Jun 19 21:37:56 EST 2006

On Mon, 19 Jun 2006 18:46:17 +0300, gerchman at research.haifa.ac.il

>Greetings all
>We are trying to measure the growth rate of rhizobium in different carbon
>sources but encountering dificulties. The main issue is that in liquide culture
>the bacteria seem to create "flakes" rather then homoginios turbidity, so
>absorbance seem out of the question. We thought about vortexing the sample and
>doing CFU count. Anyone tried this before? Any other ideas?

This is a common type of problem (in one variation or another).

The gold standard is dry weight. Anything less than that is something
you use because you are confident it works.

The relationship between A and growth depends on cell size, so even if
the cells were well suspended, using it with different C sources
raises issues.

If you are set up to run samples thru a cell counter, that would be
great. But most labs can't do that. Microscopic cell counts might
work, but get tedious.

Using viable counts raises the same basic question you started with...
Is the cell suspension well behaved in that context? You have no way
to know.

I might suggest you contact some labs actually working with your
specific organisms, and see what they suggest.


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