Respuesta :
The original concentration is 1.37 × 10⁵ CFU / ml
In order to attain a countable plate, the number of CFU must be present in between 20 and 200 per ml.
Let us take 0.1 ml and dilute it to 1 ml.
This minimizes the concentration to 1.37 × 10⁵ × 10⁻¹ = 1.37×10⁴CFU/ ml
In order to minimize the concentration in between 20 and 200, it can be reduced to 1.37 × 10²
The only number using the numerals "137" that is between 20 and 200 colonies is 137. (The closest numbers are 1370 and 1.37, but they are out of the countable range.) This is how many colonies you would expect on a correctly diluted plate.
The final concentration = 1.37 × 10² CFU/ml
Initial concentration = 1.37 × 10⁵ CFU/ml
Volume of sample with 1.37 × 10² CFU = 1.37 × 10² CFU × (1 ml / 1.37 × 10⁵ CFU)
= 1.0 × 10⁻³ ml
So, 1.0 × 10⁻³ ml volume to be taken to obtain countable value, 137 CFU.
An FDF of 10 ^ - 3 can be produced by plating 1 mL of DF 10 ^ - 3 or 0.1 mL of DF 10 ^ - 2 This is possible be- cause plating one-tenth of the volume is equivalent to another ten-fold dilution.
Learn more about dilution here ; https://brainly.com/question/21323871?referrer=searchResults
#SPJ4
