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Expansion and cultivation of test tube strains in mother strain production

                                                          Part 1

      Liquid strains are the same as solid strains. Mother strains are mostly used in test tubes. 

Production companies generally use homemade PDA culture medium, and some companies

 purchase imported or domestic culture medium powder for production.

     Culture medium formula: 200 grams of potatoes (peeled), 20 grams of glucose, 18-23 grams 

of agar strips/powder, 1000 milliliters of water, and natural pH. To ensure the quality of the strain, 

fresh potatoes with high starch content are selected; when preparing, glucose is added last to avoid 

nutrient loss; when boiling agar strips/powder in water, pay attention to using low heat and stirring 

constantly to avoid burning the pot. You can also use a water bath or microwave to heat; agar strips/powder 

are added according to the season, water quality and strain characteristics. When the amount added increases, 

the culture medium becomes hard, which may cause the mycelium growth to slow down, but the concentration 

is better; it is recommended to use purified water with stable purity for preparation. Usually 20 mm × 200 mm 

glass test tubes are filled with 12-15 ml of culture medium.

       The test tube is sterilized in a small vertical autoclave at 121°C for 20 minutes. After sterilization, 

place the bevel while it is hot. Pay attention to the temperature control of the pot, which is generally 

controlled above 50°C and below 80°C. After placement, it needs to be covered with multiple layers of 

gauze that can keep warm, etc., to minimize the generation of condensed water on the inner wall of the test tube. 

The length of the bevel is about 2/3 of the length of the test tube. It is recommended to wait for 24 hours until the

 condensed water on the bevel of the test tube disappears and no bacteria grow before use.