Question

You estimate a culture to be approximatly 10^4 CFU/ml. Devise a dilution scheme to verify

Answer 1

Dilution of culture sample in 10 fold serial dilution helps to determine the number of cells of approximately

To dilute 1 ml of sample added to 9 ml of water and it is 10-1 dilution tube

Take 1 ml from 10-1 dilution sample and add 9 ml of water to get 10-2 dilution tube

Take 1 ml from 10-2 dilution sample and add 9 ml of water to get 10-3 dilution tube

Once serially diluted we have to plate the sample by pour plate method and have to count the number of colonies

For a cell culture to have 104 cells /ml ,

the 10-1,10-2,10-3 plates should have 100 colonies, 10 colonies, 1 colony respectively