Nutrient Agar: Composition, Preparation and Uses 4.12/5 (428)

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Nutrient Agar: Composition, Preparation and Uses

Nutrient Agar is a general purpose, nutrient medium used for the cultivation of microbes supporting growth of a wide range of non-fastidious organisms. Nutrient agar is popular because it can grow a variety of types of bacteria and fungi, and contains many nutrients needed for the bacterial growth.

Composition of Nutrient Agar
  • 0.5% Peptone

It is an enzymatic digest of animal protein. Peptone is the principal source of organic nitrogen for the growing bacteria.

  • 0.3% beef extract/yeast extract

It is the water-soluble substances which aid in bacterial growth, such as vitamins, carbohydrates, organic nitrogen compounds and salts.

  • 1.5% agar

It is the solidifying agent.

  • 0.5% NaCl

The presence of sodium chloride in nutrient agar maintains a salt concentration in the medium that is similar to the cytoplasm of the microorganisms.

  • Distilled water

Water is essential for the growth of and reproduction of micro-organisms and also provides the medium through which various nutrients can be transported.

  • pH is adjusted to neutral (7.4) at 25 °C.

Preparation of Nutrient Agar

1. Suspend 28 g of nutrient agar powder in 1 litre of distilled water.

2. Heat this mixture while stirring to fully dissolve all components.

3. Autoclave the dissolved mixture at 121 degrees Celsius for 15 minutes.

4. Once the nutrient agar has been autoclaved, allow it to cool but not solidify.

5. Pour nutrient agar into each plate and leave plates on the sterile surface until the agar has solidified.

6. Replace the lid of each Petri dish and store the plates in a refrigerator.

Uses of Nutrients Agar

1. It is frequently used for isolation and purification of cultures.

2. It can also be used as a means for producing the bacterial lawns needed for antibiotic sensitivity tests.  In actuality, antibiotic sensitivity testing is typically performed on media specially formulated for that purpose.

Pictures
Four nutrient agar plates growing colonies of common Gram negative bacteria.

Four nutrient agar plates growing colonies of common Gram negative bacteria.
Source: Wikipedia

Staphylococcus aureus in nutrient agar

Staphylococcus aureus in nutrient agar.
Source: CHARLES UNIVERSITY

Staphylococcus epidermidis in nutrient agar.

Staphylococcus epidermidis in nutrient agar.                Source: CHARLES UNIVERSITY

 

 

 

 

 

 

 

 

 

 

Nutrient Agar: Composition, Preparation and Uses

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Nutrient Agar: Composition, Preparation and Uses

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The Author

Sagar Aryal

Sagar Aryal

I am Sagar Aryal, a passionate Microbiologist and the Scientific Blogger. I did my Master's Degree in Medical Microbiology and currently working as a Teaching Assistant at St. Xavier's College, Kathmandu, Nepal. I am particularly interested in research related to Medical Microbiology and Virology. Find me on Facebook, Twitter or Linkedin !!!

51 Comments

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  1. I have a whatsapp group for microbiologists.
    JOIN in this group anywhere from the world.
    if interested join. number: +966 0552568759

  2. Sir Kya nutrient agar ke composition me Maine answer bola ki kuchh water soluble vitamins aur green blue algae extract paya jata hai Mera answer Sahi hai ya galat sir please reply me I m true or false

    1. GOOD BACHCHE….VERY NICE

  3. characteristics of good solid culture media(agar)

  4. what are the characteristics of a high quality agar for bacterial growth????

  5. For 1 L media we need 0.4% yeast extract, 1% malt extract, and 0.4% glucose.

    My question is: What does % mean?
    Thanks.

  6. To prepare 1 L media we need yeast extract 0.4%. malt extract 1%, and glucose 0.4%.

    My question is: what does % mean?
    Thanks.

    1. 0.4 % of 1000 ml media is 0.48*1000/100= 4 gm/ Liter of the solute.
      1% of 1000 ml media is 1*1000/100= 10 gm/Lt.

  7. What about adding he chemical formula?

  8. What about nutrient broth ? Composition ?

  9. I am elemenatary school student researching on the different effect of different kinds of soaps. Thanks for high-quality information!

  10. I dont know about that but you can add a broad spectrum antibiotic to avoid griwth of bacteria in your plates

  11. Whats the basic defferences between all culture media
    And which culture media would use for which????

  12. Sir I have used nutrient agar for fungus culture…. Before i use PDA for culture it was gud…. But i found lots of bacterial contamination in my Nutrient agar culture…. Does the composition of beef extract hampers the groeth of fungus and favours bacteria instead.

  13. how microbes get water content while they are cultured on the nutrient agar plates

  14. What is Basal media????

    1. peptone water, Nutrient broth, and nutrient agar. non enriched general purpose media.

  15. What is Basal media

    1. It media that supports the growth of bacteria but do not need nutrients

  16. how to subculture B.pulimnus

  17. Hello I have a question. If a leg wound is cultured and it is put on a nutrient agar, Selective agar and Differential Agar what are expected to show?

  18. What is the principle or action of nutrient media?

  19. Hi ! I streaked out from sweet potato steep water and I had both red colonies and white colonies that turned nutrient agar kind of green. Please what kind of organisms are these . They areboth staining gram positive

    1. yes both are gram positive

  20. Nutrient agar favored 4 Non fastidious bacteria
    Blood agar used to detect bacteria that produce enzymes to break apart the Red blood cells
    Mac conkey agar favored 4 gram – bacteria
    sabouraud agar favoured 4 fungi
    lowenstein jensen agar favored 4 mycobacterium tuberculosis
    salmonella shigella agar favored in the isolation of salmonella&shigella

  21. the compositon and funtions were helpful. but i dont really get the beef extract could you please explain more. you did a nice job. my name is Anie, 19yr old microbiology student, i’m currently in my 3rd year in Uni

  22. among the types of medias we have can somebody help me and tell me the kind of micro organism to which each media favour the growth
    eg nutrient agar favour the growth of …..

  23. How to make agar?

    1. Agar are come from huge agar plant know as kelps .are cooked with dilute acid and filtered the acidic liquid is neutralized and cooled so that agal gel is obtained

  24. Micro organisum q zaruri h ?

  25. iam very, very interested

    1. r u indian

  26. which dye is used for nutrient agar

  27. Why bacteria are so small ?????????
    Base on Molecular weight ,taxonomically

    1. because that is how they were formed from the beginning of time

    2. r u find answer

  28. Hi, my name is Sunday J. Kerkula and I am passionate in Microbiology, and the Laboratory Assistant and Microbiologist at Monrovia Breweries Inc in Liberia.

    I am really interested in pursuing MSc in food Microbiology.

  29. what is the color of nutrient agar?

    1. go close to d practical,and the Petri dish you get to see the colour after inoculation and culture

  30. Sir/Madam,
    Could u tell me what are the microbial techniques? Just list put techniques name so that i could learn it from basics.

    Thank you

    1. Could u tell me what are the microbial techniques? Just list out the techniques name so that i could learn it from basics.

  31. thats what i learned at Tech

  32. Excellent

  33. goodnight
    I wonder about questions such as Pseudomonas aeruginosa colonies on nutrient agar?

  34. unraveling, compost curd ..meme-mim !

  35. Types of culture media?

    1. 1.Basal media
      2.Enriched media
      3.Selective media
      4.Enrichment media
      5.Differential media

  36. sir teching for me microbiology

  37. notes a really helpful .
    give us more of culture medias especially on fungal media

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