YMA Medium (Yeast Extract Mannitol Agar, DSMZ Medium 1031)

YMA Medium (DSMZ Medium 1031) is a solidified agar medium designed for the cultivation of root nodule bacteria (e.g., Phyllobacterium trifolii). It contains mannitol as the primary carbon source, yeast extract as a source of nitrogen and vitamins, and mineral salts to support bacterial growth. Unlike YMA Agar with calcium carbonate, this formulation does not contain CaCO₃, making it suitable for experiments where carbonate precipitation is not required.

Applications:

• Cultivation and maintenance of Rhizobium and related root nodule bacteria

• Microbiological research on symbiotic nitrogen-fixing bacteria

• Soil microbiology studies

• General agar-based culture of plant-associated bacteria

Specifications:

• Form: Powder, 250 g/bottle

• Storage: Room temperature

• Shelf Life: 3 years

Formula (per liter):

• Mannitol – 10.0 g

• Yeast Extract – 0.3 g

• K₂HPO₄ – 0.2 g

• MgSO₄·7H₂O – 0.2 g

• NaCl – 0.05 g

• Agar – 15.0 g

• Final pH: 7.0 ± 0.2 (25℃)

Preparation Instructions:

1. Weigh 25.75 g of the medium and suspend in 1 liter of distilled or deionized water.

2. Heat and boil for at least 1 minute until the agar is completely dissolved.

3. Dispense into suitable containers.

4. Sterilize by autoclaving at 121℃ for 15 minutes.

5. Cool to approximately 50℃, mix gently, pour plates, allow to solidify, and store under sterile conditions.