Nutrient Agar- Principle, Composition, Preparation and Uses

Nutrient Agar- Principle, Composition, Preparation and Uses

Nutrient Agar is a general-purpose medium for the cultivation of a wide variety of bacterial organisms. This medium is best prepared from ready to use dehydrated powder, available from most suppliers of culture media.

Nutrient Agar- Principle, Composition, Preparation and Uses

Principle of Nutrient Agar

Nutrient Agar consists of peptone, beef extract and agar. This relatively simple formulation provides the nutrients necessary for the replication of a large number of microorganisms which are not excessively fastidious. The beef extract contains water soluble substances including carbohydrates, vitamins, organic nitrogen compounds and salts. Peptones are the principle sources of organic nitrogen, particularly amino acids and long-chained peptides. Sodium chloride maintains the osmotic equilibrium of the medium. Agar is the solidifying agent.

Composition of Nutrient Agar

Composition per liter:
Agar ………………………………………………………………………………….15.0 gm
Peptone………………………………………………………………………………..5.0 gm
Beef extract ………………………………………………………………………….3.0 gm
Sodium chloride …………………………………………………………………….5.0 gm
pH 7.4 ± 0.2 at 25°C

Preparation of Nutrient Agar

  1. Add 28 gm of components to distilled/deionized water and bring volume to 1.0 L.
  2. Mix thoroughly.
  3. Gently heat and bring to boiling.
  4. Distribute into tubes.
  5. Autoclave for 15 min at 15 psi pressure 121°C.
  6. Allow tubes to cool in a slanted position.

Uses of Nutrient Agar

Nutrient Agar is used for the cultivation of bacteria and for the enumeration of organisms in water, sewage, feces and other materials.

Nutrient Agar- Principle, Composition, Preparation and Uses

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