Continuous culture, also known as open culture, is relative to batch culture or closed culture. Continuous culture is a kind of culture method that takes effective measures to keep microorganisms growing vigorously in a specific environment.

Microorganisms are placed in a certain volume of culture medium, cultured for a period of time, and finally harvested at one time, which is called batch culture. In batch culture, the culture medium is added at one time and is not supplemented. With the active growth and reproduction of microorganisms, nutrients are gradually consumed and harmful metabolites are accumulated, so it is impossible to maintain the logarithmic growth period of bacteria for a long time.

On the basis of studying the typical growth curve, continuous culture recognizes the reason for the arrival of stable period, and adopts the method of constantly supplementing fresh nutrients in the incubator and stirring evenly; On the other hand, the culture (including bacteria and metabolites) is continuously discharged at the same speed in time, so that the culture reaches a dynamic balance, and the microorganisms in it can maintain a logarithmic phase balanced growth state and a stable growth rate for a long time. Continuous culture can not only provide experimental materials in a certain physiological state for microbial research at any time, but also improve the production efficiency and automation level of fermentation industry. This method has become the development direction of fermentation industry.