Problem with MPN

[Alan Hochberg]

Daniel,

If I understand your question, it's perfectly OK to do serial pre-dilutions
when using an MPN method.  In fact, the MPN method doesn't work well if
overloaded (e.g. 3-3-2) or underloaded (1-0-0).

Make sure you mix your pre-dilutions well so you get a uniform distribution
of organisms, and simply multiply your answer by your pre-dilution factor
when you're done.  One more thing: remember that to dilute by a factor of
10, you add 1 ml of your sample to NINE (9) ml of broth, not 10 ml.

Good luck,

Alan Hochberg
http://members.aol.com/nicestalan/