you serially dilute a bacterial culture to 1x106 spread 100

you serially dilute a bacterial culture to 1x10^-6, spread 100 microliters of this dilution onto a nutirent agar plate, incubate overnight, and in the morning you count 37 colonies. What was the cell concentration in the original culture

Solution

Answer:

Given:

Dilution factor= 1/10^6

Number of colonies= 37

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 = (37)/ (1/10^6 x 0.1)

cfu/ml = 37 x 10^7

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