O.D. 600 nm readings to bacterial concentrations

Michael F. Hynes hynes at acs.ucalgary.ca
Wed Oct 4 13:42:16 EST 1995

Unfortunately you will have to do the experiment of making plate counts 
at different OD 600s and setting up a standard curve. This is a lot of 
work but there is no way around it as far as I know. If anybody out 
there knows differently I would love to hear from her/him. 

We have found that with Rhizobium you can't even extrapolate from one 
strain to another as things like EPS production can result in 10-fold 
differences in cfu at the same OD. I believe this fact is also mentioned 
in Sambrook et al. re; E. coli strains.

Then every time you change medium you have to set up a new calibration.

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