The Dilution Coating Plate method involves a series of gradient dilutions of the bacterial solution, and then the different dilutions are applied to the surface of agar solid medium for incubation. In a sufficiently high dilution of the bacterial solution, the aggregated microorganisms will be dispersed into individual cells, which can form individual colonies on the surface of the medium.

Dilution plate coating is mostly used for counting the number of bacteria, and it is not known which dilution concentration finally grows out to have the number of colonies suitable for counting, so the plate must be coated at each dilution.

Methods for pouring plates

If diluted properly, a scattered single colony can appear on the surface of the plate or in the agar medium, and this colony may be formed by the multiplication of a single bacterial cell. Subsequent picking of that single colony, or repeating the above operation several times, results in a pure culture.

There are two ways to condense the plate culture medium, one is to spread the plates one by one on the table to condense, the other way is to stack several plates together to condense. The former condensation speed is faster, in the room temperature is higher when used; and the latter condensation speed is slower, can be used in the room temperature is lower, the advantage is the formation of condensate less, especially suitable for plate marking and other needs.

Reference: Baidu Encyclopedia - Dilution of the inverted plate method