mccardaj at esvx17.es.dupont.com mccardaj at esvx17.es.dupont.com
Sun Apr 2 09:41:07 EST 1995

In article <3lc215$51r at newshound.uidaho.edu>, kellogg at raven.csrv.uidaho.edu (Scott Kellogg) writes:
>Try the following:
>OD550 = (1.0315e-8)(cell number/ml)+1.7633e-3
>The r-squared for this regression is 0.9997 and the data are for the 
>genus Vibrio (taken from Primrose & Wardlaw, 1982, Sourcebook of 
>experiments for the teaching of microbiology, p. 151).  This equation is 
>valid only for ODs from 0.02 to 0.50, and in general one should be use 
>ODs less than 1 for accuracy (so dilute).
>Wayne A Sargent (wsargent at badlands.NoDak.edu) wrote:
>: I would truly appreciate a formula for converting an OD reading 
>to #bacterial cells/ml.
If possible, I too would love to be able to use this formula for converting
an OD reading into cell concentration.  I am doing an experiment with about
15 different bacteria and was planning on generating an OD vs cell count
curve for each one.  You mentioned that the data that generated the above
formula was for Vibrio.  How applicable is it to other Genera?  I don't
need to be incredibly accurate for the experiment I'm doing.  Sure would be
great not to have to generate all those curves.

Thanks for any comment,
A.J. McCardell

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