heath at mbcf.stjude.org
Thu Nov 16 15:51:46 EST 1995
In article <48angu$6v3 at lyra.csx.cam.ac.uk>, rgs at mole.bio.cam.ac.uk (Robert Solomon (Bioc)) writes:
> mantei at neuro.biol.ethz.ch (Ned Mantei) writes:
>>doerner at papin.HRZ.Uni-Marburg.DE (Doerner Wolfgang) wrote:
>>> anyone out there who knows what a Klett-Unit is?
>>I used a Klett spectrophotometer as a student in the 1960's, and even then
>>had the impression that the instrument was an old design (1940's?). The
>>absorbance was indeed measured in "Klett units", but I don't know how many
>>correspond to an O.D. unit.
> The Klett was basically a value for light-scattering by bacterial suspensions.
> You will not be able to convert to OD600 or to cell density (cfu/mL) with
> any reliability (as all these measures are strain ependent, as so often noted
> in similar discussions in this newsgroup). When it comes to that, OD600 is
> only a light-scattering measure too, so sneer not at the humble Klett.
> On the instrument I was raised on, Klett 40 was early log, 100 about mid-log
> and growth normally plateaued at around 350. For coli (a K12 derivative).
> Wouldn't like to bet this is the same for all Klett machines or strains.
We still use Klett meters here in Memphis... they work well! We have two, and
each give slightly different readings for the same strain/media. Thus, each
Klett meter has to be calibrated by plating cells out and plotting a graph.
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