A 50 mL stock sample of cells is diluted 110 six times If 01

A 50 mL stock sample of cells is diluted 1/10 six times. If 0.1 mL of the most dilute sample generates 75 colonies on an agar plate, calculate the original concentration of bacteria present in the original sample?

Solution

Answer:

Given:

Dilution factor= 1/10^6

Number of colonies= 75

Volume of sample = 0.1 mL to the plate

CFU/ml = ?

cfu/ml = (no. of colonies)/ dilution factor x volume of culture plate

cfu/ml = (75)/ (1/10^6 x 0.1)

cfu/ml = 75 x 10^7