Hi,
I have calculated the cfu/ml of bacteria by serial dilution method ( by spreading 100ul of diluted bacterial culture on N-agar plates and counting the no. of colonies after overnight incubation) At 10-5 dilution, i have calculated cfu which comes out to be 1.2×108 cfu/ml. Now how much volume of bacterial culture should i take to have 1.2×108 no. of bacterial cells? Please help.
Hi Saleha,
You have obtained 1.2×10^8 cfu/ml at 10^-5 dilution.
It means that the bacterial culture contains 1.2×10^8 × 10^5 cells/ml.
So, X ml of culture that contains 1.2×10^8 bacterial cells equal to: 1.2×10^8/1.2×10^8×10^5= 10^-5 ml.
It means you need to take 10^-5 ml of bacterial culture (or 10^-2 ul of bactetial culture) to obtain 1.2×10^8 bacterial cells.
Best wishes
If you calculated the CFU to be 1.2×108 cfu/ml and you want 1.2×108 cells, then you need 1ml of your culture (I'm presuming this is what you calculated as your final CFU and not the CFU in your 10-5 dilution which would be impossibly high).
Hi Saleha,
I agree with the answer given by Dr Michael. If 1.2×108 CFU/ml is the final CFU of your initial cell culture you have to take 1 ml from your initial culture. But if this CFU value is for your 10-5 dilution then you have to back-calculate to find out the count in your initial solution.
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