PDA tubes cause agar not to coagulate completely
Agar: The English name is agar, and the A in the edible fungus mother culture medium PDA refers to agar, which is a vegetable glue made from seafood unicorn, stone cauliflower, Gracilaria, etc. Because it mainly comes from Hainan, it is called "agar". Agar is a substance that must be used in the edible fungus mother culture medium, which plays the role of fixing the inclined surface of the medium, and the mycelium cannot use the nutrients of agar.
After entering June, friends often ask the PDA medium, the amount of agar added is the same as before, why can't it be completely solidified now? The amount of agar added to the PDA medium is 2%, that is, 1000ml medium is added with 20 grams of agar. We analyze several reasons why agar cannot be completely solidified.
1 Excessive sterilization
The sterilization effect is determined by two parameters: temperature and time. The sterilization temperature of the PDA test tube medium is 121 ° C, and the time is 20-30 minutes. If one of the two parameters exceeds, it is easy to cause the agar to not solidify.
Solution: The sterilization time of PDA test tube medium is 121 ° C, and 30 minutes is enough. For liquid medium, the sterilization temperature of 121 ° C is sufficient, and it is wrong to increase the sterilization temperature to 125 ° C in order to ensure the sterilization effect.
2 less agar added
The amount of agar added is less than 2%, or the inaccurate weighing causes the agar to not solidify.
Solution: Ensure that the amount of agar added is 2%, correct the balance, and ensure accurate weighing.
3 poor quality agar
The use of inferior or long-term storage agar may cause the agar to not solidify.
Solution: Use high-quality agar, and be sure to use agar powder if conditions permit. Agar strips are food additives, and agar powder is an experimental reagent with reliable quality.
4 The amount of water added is not allowed
When configuring the medium, adding too much water can cause the agar to not solidify.
Solution: Add water accurately, and re-weigh after boiling. Use a measuring cylinder or a corrected beaker for weighing.
Agar precipitation at 5 pcs
When packing, if the agar is not completely dissolved, it is easy to precipitate, so that the concentration of the agar first is low, and it cannot be completely solidified.
Solution: To achieve complete dissolution, while stirring, while packing, uniform.
6pH is too low
If the pH is below 4.5, the medium will acidify and the agar will not solidify.
Solution: The main reason for the acidification of the PDA medium is the pH of the water, so try to use bottled water, which is weakly alkaline and stable.
7 High ambient temperature
In summer, in some factories without air conditioning, the temperature of the PDA culture gene environment is too high to fully solidify.
Solution: In summer, the addition ratio of 1000ml medium can be increased to 22 grams. If it needs to be added to 30 grams to solidify, it means that there is a problem with the quality of the agar. If conditions permit, air conditioners can be installed.
