Most of the study methods I read were using CFU to determine the quantity of bacteria for the studies (mostly due to the fact that OD can't distinguish dead or live bacteria). It makes sense if the experiment is about cytotoxicity, antibiotic screening etc. What if I am interested in comparing different bacteria challenged cytokine induction profiles? Since dead bacteria particle could also induce cytokine release, would the CFU based method create a bias?
Hi Christina,
Thank you for the suggestions. I am wondering is there a guideline that discusses about fixed OD or MOI for different types of experiments?
It very much depends upon the type of experiment you are doing to ascertain which makes the most sense to use. However one major downside of CFU determination is that you only know the number post-facto, ie the next day. So it can be hard to use CFU during an experiment, rather it just tells you how many colonies you had afterwards.
It might be easiest to determine an OD curve with CFU and possibly counting chamber analysis to ascertain the cell numbers at any given OD for your strain. Then you can use the OD value for quick measurements but correlate it to either CFU or total cell number based on your curve.
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