Question

Three different concentrations of bacteria
CFU are needed in a volume of 0.2mL.
What is the total CFU needed to achieve all
concentrations at a volume of 0.2 mL each?
Concentrations:
V1​

Answer 1

Explanation:

To find out the number of CFU/ ml in the original sample, the number of colony forming units on the countable plate is multiplied by 1/FDF. This takes into account all of the dilution of the original sample. For the example above, the countable plate had 200 colonies, so there were 200 CFU, and the FDF was 1/4000.