Importance of serial dilution in microbiology

This means that 44000000 bacteria were present in 10g of food. Then, all it takes is some quick arithmetic to work out how many were in the 10g of food! The bottom right plate, at a dilution of 1/1000000, had 44 colonies. The sample needs to be diluted all the way down to 1/1000000 from the original 10g suspension to allow countable colonies. They form a confluent lawn of growth across the entire medium. At a dilution of 1/10, there are far too many bacteria to be counted. After taking 10g of food and homogenising it with diluent, in the case of food tests, one millilitre of this solution would be added to agar, and incubated.Д®ach blue-green dot you see in the agar is representative of a single bacterium, which has grown into a colony.

Plate one (top left) could be an example of a food sample tested in our lab with a very high bacterial load. From left to right, each plate contains a 1 in 10 dilution of that high concentration solution, then a 1 in 10 dilution of that, and so on and so forth. In the timelapse video shown, a high concentration of E.coli was suspended in agar on the top left plate. No matter how many bacteria are in your initial sample, you can always dilute it down to a countable level.

Accurate dilutions are one of the best used tools in microbiology for determining the number of microbes in something.

Importance of serial dilution in microbiology