How many E. coli = 1 O.D. unit?

Stephen Mamber mamber at
Thu Jul 6 16:12:26 EST 1995

In article <zjons-2906951004310001 at>, zjons at (Zophonias O. Jonsson) says:
> In article <3sb250$nbu at>, "Edward K.L. Chan"
><echan at> says:
>>   I wonder if someone may be able to provide a reliable formula to calculate
>>the number of DH5-alpha or XL1-Blue based on O.D. measurement.  

>I have seen various conflicting values for estimating E. coli titers from
>OD600.  They differ by more than an order of magnitute. 

I recommend reading ODs at 0.5 or less.  Values greater than 0.5
are notoriously nonlinear due to the turbidity of the cell suspension.


mamber at

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