John W. Patching John.Patching at UCG.IE
Wed Mar 29 04:14:45 EST 1995

>Resent-date: Tue, 28 Mar 1995 22:37:53 +0000 (UT)
>Date: Tue, 28 Mar 1995 20:24:07 +0000 (GMT)
>Resent-from: server-daemon at dl.ac.uk
>From: wsargent at badlands.NoDak.edu (Wayne A Sargent)
>Subject: CELL #

>I would truly appreciate a formula for converting an OD reading
>into an approximate # of bacterial cells/ml.
Sorry, Wayne - there is no "quick fix"!  Get  your culture/cell suspension
- do a cell count - do dilutions - prepare a standard curve.  Finding
"magic" formulae and deciding which is the "right" one to use will probably
take longer!
 Donning my editor's/referee's hat, I feel that quoting unconverted OD's or
a conversion done using someone's "universal" conversion factor is not far
removed from saying that your culture looks "cloudy" or "not so cloudy".
OD's are so easy to take.  Please folks - do that little bit extra and
convert them into something which is meaningful and reproducable by other

John W. Patching
The Martin Ryan Marine Science Institute
University College Galway, Ireland

Email: John.Patching at UCG.IE
Phone: +353-91-24411 Ext 2398
Fax:       +353-91-750456

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