Dear Reseaeches
Greetings
Can anyone help me about the CFU (Colony Forming Units)? How do I calculate or determine CFU (Colony Forming Units) from the respactive plates and if I have 0 to 5 dilutions then which will be the actuall dilution factor? please gide me about that I will wait for your positive or good response
Thanks
What do you mean the actual dilution factor? Since all plates have different dilutions... you count the plates that have colonies and aren't overgrown and calculated it back to the 0 dilution.
For our work, we almost always plate at least 3 dilutions per sample, just so we can hit a dilution on a plate we can count. We usually always do a 1/10 serial dilution. For example:
if you have 10 colonies in 0 dilution and you plated 100uL of the 0 diluted sample than you will have 10x10 (becuase you only plated 100uL) = 100 CFU/mL
If you have 7 colonies in a -2 (which in our case would be a 1/100 dilution) and you plated 100uL of the -2 than you will have 7x100x10 = 7000 CFU/mL
If you did your serial dilution more or less evenly, you should have fairly close numbers. For example...
If you have 100 colonies at a -1
then you should have around 10 colonies at the -2
and around 1 colony at -3
Since I do my serial dilutions by dividing by 10.
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