3 A hamburger sample was diluted 10 2 and then 01 ml of the

3. A hamburger sample was diluted 10 2 and then 0.1 ml of the 10 hamburger suspension was plated on nutrient agar. Incubating for 48 hours at 37 C, 58 colonies appeared. What is the original concentration? How many CFU per 100ul

Solution

Colony forming unit = number of colony* Dilution factor/volume of culture

10^-2 dilution means 100 time dilution so the dilution factor will be 10²

= 58*100/0.1

= 58*10⁴ cfu/ml

in 100 ul it will be 58*10³