Since the bacterial material is now added to the still hot medium and then inverted plate is easy to cause the death of some heat-sensitive bacteria, and the use of dilution of inverted plate method will also make some strictly aerobic bacteria because of the lack of oxygen in the middle of the agar is fixed to affect the growth of the bacteria, therefore, in the microbiological research in the more commonly used method of isolation of pure species is the dilution of coated plate method.

Used for the validation of partially finished products, the testing of biological products, the determination of bacterial content in soil, and the testing of the degree of contamination of food and water sources. The sample to be tested is made into a homogeneous series of dilutions to disperse the microbial cells in the sample as much as possible so that they are in single-cell form.

Characteristics:

Dilution plate counting is based on the microorganisms in the solid medium formed by a single colony, that is, from a single cell reproduction of the culture characteristics of the design of the counting method, that is, a colony represents a single cell.

When counting, the sample to be tested is first made into a homogeneous series of dilutions, as far as possible to make the microbial cells in the sample dispersed, so that the existence of a single cell (otherwise a colony does not just represent a single cell), and then take a certain degree of dilution, a certain amount of dilution inoculated to the plate, so that it is uniformly distributed in the plate within the culture medium.

After cultivation, the colonies are formed by the growth and reproduction of individual cells, and the number of colonies is counted to calculate the number of bacteria in the sample. The number of bacteria calculated by this method is the number of colonies grown on the culture medium, so it is also known as live bacteria counting. Generally used for certain finished product certification (such as insecticidal fungicides, etc.), biological products testing, soil bacterial content determination and food, water pollution level of the test.