Beef paste peptone medium is the most widely used and common basic bacterial medium, sometimes called common medium. Because this culture medium contains the most basic nutrients needed for the growth and reproduction of general bacteria, it can be used for the growth and reproduction of microorganisms. The basal medium contains beef paste, peptone and NaCI. Among them, beef paste provides carbon source, energy, phosphate and vitamins for microorganisms, peptone mainly provides nitrogen source and vitamins, while NaCI provides inorganic salts. When preparing solid culture medium, a certain amount of agar should be added as coagulant, and the agar will melt at 96℃ at the usual concentration. In practical application, it is usually boiled and melted in a boiling water bath or under it with asbestos mesh to avoid burning the agar. Agar solidifies at 40℃ and is usually not decomposed and utilized by microorganisms. The content of agar in solid medium varies according to the quality of agar and the temperature.

Because this kind of culture medium is mainly used to cultivate bacteria, it is necessary to adjust its pH to neutral or slightly alkaline with dilute acid or alkali to facilitate the growth and reproduction of bacteria.

The formula of beef paste peptone culture medium is as follows:

Beef paste: 3.0 g

Peptone: 10.0 g

NaCI：5.0 g

Water: 1 000 ml

pH：7.4-7.6