Semisolid Nutrient Agar is a universal basic microbiological medium. Prepared based on nutrient agar with a reduced agar dosage to form a semisolid gel, it balances fluidity and support performance. It serves as a core consumable for routine microbial testing, strain preservation and biochemical assays in microbiology laboratories. This product is a pale yellow powdered dehydrated culture medium with a well-balanced formula, excellent solubility and high clarity of prepared medium. It stably supports the cultivation, motility testing and short-term preservation of various bacteria. It is widely applied to microbial detection in food, pharmaceutical, water quality, animal husbandry, scientific research institutes and other fields, complying with national standards and general industrial testing specifications. It is also used for motility observation, strain storage and H antigen phase variation tests.
Principle and Purpose:
Peptone and beef extract powder supply nitrogen sources, essential vitamins, minerals, amino acids and other nutrients required for microbial growth; sodium chloride maintains balanced osmotic pressure; agar acts as the gelling agent.
Formula: (g/L)
Peptone
| 10.0 g
|
Beef Extract Powder
| 3.0 g
|
Agar
| 4.0 g
|
Sodium Chloride
| 5.0 g
|
Final pH (25°C)
| 7.2±0.2
|
Preparation Method:
Weigh 22.0 g of this product and add into 1 L of purified water. Heat and boil until completely dissolved, dispense into test tubes, autoclave at 121°C for 15 minutes, place upright to solidify, then set aside for use.
Quality Control:
Test Item
| Standard Index
|
Appearance
| Powder
|
Color of dehydrated medium
| Pale yellow
|
Color of prepared medium
| Pale yellow semisolid
|
Final pH (25°C)
| 7.2±0.2
|
Microbiological Testing:
Testing items are detected in accordance with the Pharmacopoeia of the People's Republic of China: Escherichia coli, Bacillus cereus and Shigella flexneri.
Quality Control Strains and Strain Numbers
| Growth Status / Colony Characteristics
|
Escherichia coli CMCC(B)44102
| Good growth with diffuse spreading growth
|
Bacillus cereus CMCC(B)63303
| Good growth with diffuse spreading growth
|
Shigella flexneri CMCC(B)51572
| Good growth, growing only along the stab line
|
Inoculation mode: Qualitative test.
Incubation conditions: 35 °C, 24 hours
Precautions:
1. Wear necessary protective equipment when weighing the medium to prevent physical discomfort.
2. Store the medium in a dry and dark place. Tighten the cap immediately after use to avoid moisture absorption and caking.
3. Discard used medium only after autoclaving at 121 °C for 30 minutes.
4. This product shall not be used for clinical testing.
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