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You are given a stock culture and told that it has approximately 5x10^10 CFU/ml. Devise a...

You are given a stock culture and told that it has approximately 5x10^10 CFU/ml. Devise a serial dilution scheme so that you will get countable colonies when plating 100 microliters.

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Answer #1

Serial Dilution :

A serial dilution is the stepwise dilution of a substance in solution.

Usually the dilution factor at each step is constant, resulting in a geometric progression of the concentration in a logarithmic fashion.

A ten-fold serial dilution could be 1 M, 0.1 M, 0.01 M, 0.001 M ... Serial dilutions are used to accurately create highly diluted solutions as well as solutions for experiments resulting in concentration curves with a logarithmic scale.

Calculation of Serial dilution :

Number of colonies on plate x Reciprocal of dilution of sample = Number of Bacteria / ml,

for example, if 45 colonies are on aplate of 1/100 dilution, then the count of 45 x 100 = 4500/ml in sample.

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