Algae cultivation must first have algae species. From the mixed biota in natural waters, a certain method is used to separate the required algae individuals and obtain pure culture. This method is called algae separation and purification, also known as pure culture method.

Changing culture medium conditions can also help isolate strains. For example, in order to obtain thermophilic microorganisms, the microorganisms can be cultured at 50℃~60℃. Sometimes adding corresponding inhibitors can also improve the bacterial strain separation effect.

For example, adding a few drops of 10% phenol to the suspension of soil samples can inhibit the growth of molds and bacteria and facilitate the isolation of actinomycetes. Adding a certain amount of penicillin or streptomycin to the culture medium can inhibit the growth of bacteria and facilitate the isolation of mold.

Medium and bacterial strain isolation refers to the operation technology of obtaining pure microorganisms from samples containing multiple microorganisms. Bacteria isolation is mainly performed on petri dishes, and the commonly used methods are the dilution method and the streaking method. The purpose of using these two methods is to reproduce an individual microorganism and grow a visible colony on a solid medium.

Then, according to the culture characteristics, use an inoculation needle to pick up the required bacterial strain and examine it under a microscope to prove that it is a single-shaped bacterial cell. Commonly used media are selective media. For example, the culture medium used to isolate cellulose-decomposing microorganisms is a medium using cellulose as a carbon source, because only cellulose-decomposing microorganisms can grow from this medium.