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

Brad Nicholson brad at
Thu Jun 22 17:29:29 EST 1995

In article <3sb250$nbu at>, "Edward K.L. Chan" 
<echan at> wrote:

> Hi netters,
 >   I wonder if someone may be able to provide a reliable formula to 
 >the number of DH5-alpha or XL1-Blue based on O.D. measurement.  Thanks in

Generally, I take an O.D. A600 of 1.0 to equal 1 x 10^9 cfu.  If you really
want accuracy I would suggest doing viable counts at O.D. points as the 
culture grows.

Good Luck

Brad Nicholson              |"If it worked the first time, it wouldn't be 
Department of Pathology     |	research."...Brad Nicholson
University of Utah          |	Live from behind the Zion Curtian.
Salt Lake City, UT 84132    | 
brad at    |
or: (801)-581-4365          | My opinions are solely my own.

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