What are the methods to separate and purify microorganisms? Which strains are suitable for isolation by each method?

1, dilution inverted plate method

Firstly, the microbial suspension is diluted in series (for example, 1: 10, 1: 100,1000, 1: 1000). If diluted properly, scattered single colonies can appear on the surface of the plate or in agar medium, which may be formed by the reproduction of bacterial cells. Then pick a single colony, or repeat the operation for more than a few times, and you can get pure culture.

2. Dilution coating plate method

Pour the melted culture medium into a sterile plate to make a sterile plate, after cooling and solidification, drop a certain amount of microbial suspension on the surface of the plate, then use a sterile glass smear rod to evenly disperse the bacterial liquid on the whole plate surface, and pick out a single colony after culture.

3, flat line method

Microbial samples were diluted many times on the surface of solid medium from point to line to realize separation.

4, dilution shake tube method

Firstly, a series of test tubes filled with sterile agar medium were heated to melt the agar, and then cooled and kept at about 50℃. The substances to be separated are diluted with these test tubes in gradient, and the test tubes are shaken quickly. After condensation, a layer of sterilized mixture of liquid paraffin and solid paraffin was poured on the surface of agar column to separate the culture medium from the air.