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

To: Nikolai troianovsk_s at MSdisk.WUstl.EDU
Fri Jun 23 19:38:12 EST 1995


>Hi netters,
>   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.  Thanks in
>advance.
> 
 

Hi, there.

Here it goes:
     GENERAL:
4-9 x 10^7 cells/ml corresponds to a culture of rec (-) strains at O.D.550
of 0.35-0.60; and to cultures of rec (+) strains at O.D.550 of 0.2-0.4.
     For DH1 cells:
4-7 x 10^7 cells/ml corresponds to an O.D.550 of 0.45-0.55.
     For x1776 cells:
5-7 x 10^7 cells/microL corresponds to an O.D.550 of 0.2.

The numbers taken from "DNA cloning a practical approach" Vol.I, ed. D.M.Glover.

Good luck,
Nikolai





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