cheap probe to detect log growth

ianj ianj at
Sun Dec 3 00:41:36 EST 2000

Michael Witty wrote in message ...
>Dear All, I am convinced there must be a better way of finding the log
>phase of growth (for example of a conical flask of E. coli) than
>repeatedly taking 1ml samples and putting them in a spec.

I think that this instrument already exists: it's called a nephelometer. It
measures relected light rather than transmittance (as in a
spectrophotometer). It is accurate (linear) over a wide range of cell
concentrations. It is also quite robust. I've seen them as a probe that
could be inserted into flasks.

Also, no need to distinguish between live and dead cells because in an
application of measuring lag phase and then logarithmic growth the
assumption of 100% viability is valid.

There is also an instrument that has been advertised for the measurement of
yeast growth in the brewing industry- i'm not sure what principle it works



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