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.