What is the definition of separation and purification?

Separation and purification is defined as the process of separating a polysaccharide mixture into a single polysaccharide.

Cultures containing more than one microorganism are called mixed cultures. If all the cells in a population come from one parent cell, then the population is called pure culture. When identifying strains, it is generally required that the microorganisms used are pure cultures. The process of obtaining pure culture is called separation and purification, and there are many methods.

1, inverted plate method

Firstly, the microbial suspension is diluted in series, and a certain amount of diluent is fully mixed with the melted nutrient agar culture medium maintained at about 40-50 degrees. Then, the mixed solution is poured into a sterile Petri dish, and after solidification, the plate is inverted in a constant temperature box for culture. Multiplying a single cell for multiple times to form a colony, taking the single colony to make a suspension, and repeating the above steps for several times to obtain a pure culture.

2, coating plate method

Firstly, the microbial suspension is diluted properly, and a certain amount of diluent is put on the sterile solidified nutrient agar plate, and then the diluent is evenly coated on the surface of the culture medium with a sterile glass scraper, and the single colony can be obtained after constant temperature culture.

3, flat line method

The simplest method to separate microorganisms is the plate scribing method. Take a little culture with sterile inoculation ring and spread it on the plate. There are many methods of drawing lines, and the common methods of drawing lines that are prone to single colony are diagonal line method, curve method, grid method, radiation method, four-grid method and so on. When the inoculation ring moves backward on the surface of the culture medium, the bacterial liquid on the inoculation ring is gradually diluted, and finally individual cells are scattered on the drawn line, and each cell grows into a colony after culture.