Nutrient Agar and Nutrient Broth: Composition, Preparation & Differences (2024)

Nutrient agar (CM0003B) and nutrient broth (CM0001B) from Oxoid share almost the same medium composition. The main difference between them is that nutrient agar contains a solidifying agent, agar powder that causes the medium to solidify in room temperature, whereas nutrient broth remains in liquid form.

What is Nutrient Agar?

Nutrient agar contains nutrients that suitable to subculture a wide range of microorganisms and makes it an excellent agar media to check on the purity before any biochemical or serological test.

Besides, the addition of agar solidifies nutrient agar, which makes it suitable for the cultivation of microorganisms. You can also add up to 10% blood or other biological fluids that meet your experimental purpose.

How to prepare nutrient agar?

• Suspend 28g of nutrient agar powder (CM0003B) in 1L of distilled water.
• Mix and dissolve them completely.
• Sterilize by autoclaving at 121°C for 15 minutes.
• Pour the liquid into the petri dish and wait for the medium to solidify. Be sure that you are preparing the agar in the clean environment to prevent any contamination.

Once the agar solidifies, the agar is ready to use.

** Here’s a tip for you to ensure that your prepared agar is sterile. You can incubate your freshly prepared agar in an incubator for a few days. If there aren’t any microorganisms grow on the agar, you are safe to use it, else, prepared again!

What are the storage condition and shelf life for nutrient agar?

You have to store the dehydrated medium at 10-30°C and use before the expiry date on the label. Once you prepare the nutrient agar in the petri dish, store them at 2-8°C.

For more information, please visit Nutrient Agar, Oxoid.

What is Nutrient Broth?

Basically, the nutrient broth is the nutrient agar that lack of the solidifying agent, agar powder. They remain in liquid form at room temperature and are usually used to maintain the stocks of microorganisms. In general, they are used to grow fastidious organisms. Also, you can enrich your nutrient broth with blood, serum, sugars… etc for special purposes.

How to prepare nutrient broth?

• Add 13g of nutrient broth powder (CM0001B) in 1L of distilled water.
• Mix and dissolve them completely.
• Pour them into the final containers (eg. conical flask)
• Sterilize by autoclaving at 121°C for 15 minutes.

What are the storage condition and shelf life for nutrient broth?

You have to store the dehydrated medium at 10-30°C and use before the expiry date on the label. Once you prepare the nutrient broth medium, store them at below 25°C.

For more information, please visit Nutrient Broth, Oxoid.

Composition of Nutrient Agar and Nutrient Broth

Differences between nutrient agar and nutrient broth