Principle
- Ashbys mannitol agar is described by Subba Rao (1977) for the isolation of a non-symbiotic nitrogen-fixing bacteria, Azotobacter. Ashby’s media is composed of mannitol, dipotassium phosphate, magnesium sulfate, sodium chloride, potassium sulfate, and calcium carbonate.
- Mannitol provides carbon sources and atmospheric nitrogen serves nitrogen sources. Dipotassium Phosphate is a buffering agent. The other salts provide various essential ions required for promoting the growth of Azotobacter.
- The presence of calcium carbonate stimulates growth and increases the availability of phosphorus, sulfur, and magnesium to the organisms.
Use:
Recommended for isolation of mannitol fermenting Azotobacter from soil samples.
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PARAMETERS
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STANDARD VALUES
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PHYSICAL PARAMETERS:
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Dehydrated Powder
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Description
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A fine, free-flowing, hygroscopic powder.
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Color
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Off-white colored powder.
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Solution
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Solubility
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Soluble in Distilled / de-ionized water at 50˚ C
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Color
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Milky white colored solution with stealing at the bottom on standing
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pH
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7.4 ±0.2 at 25 ˚C (40.70 g/ l)
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Agar Plates
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Solidification
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40 ˚C
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Color
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Milky white colored opalescent gel with slight precipitate.
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