I've never worked with Rhizobia, but in the past when faced with this
sort of problem we did the following:
Put an aliquot of the liquid culture in a 13 X100 mm tube. Spin down
the cells. Add about 5 ml 1.0N NaOH, put in boiling water bath for
about 30 minutes, cool, add Biuret reagent. Wait however many of
minutes the Biuret reaction takes ( I don't remember right now) and
then read in a spectrophotometer. Standardized against a known protein
like bovine serum albumin of lysozyme, this gives you total protein in
your culture aliquot.
That is not cell number but all things considered a reasonable
surrogate. Protein content varies by about a factor of two, and cells
usually don't accumulate extracellular proteins, so It is a
reasonable and quick (and cheap approach). Whether it is applicable
to Rhizobia, I do not know.
David
gerchman at research.haifa.ac.il wrote:
> 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?
> Thanks Yoram
>> ----------------------------------
> "Support bacteria, it's the only culture some people have"
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