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Nutrient Agar

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SKU:
M001
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A general purpose media used for cultivation of less fastidious microorganisms and can be enriched with blood or other biological fluids.

Intended use

Nutrient Agar is used as a general purpose medium for the cultivation of less fastidious microorganisms, can be enriched with blood or other biological fluids.

Composition**

Ingredients g/L
Peptone 5.000
Sodium chloride 5.000
HM peptone B# 1.500
Yeast extract 1.500
Agar 15.000
Final pH (at 25°C) 7.4±0.2

**Formula adjusted, standardized to suit performance parameters

# - Equivalent to Beef extract

Directions

Suspend 28.0 grams in 1000 ml purified / distilled water. Heat to boiling to dissolve the medium completely. Sterilize by autoclaving at 15 lbs pressure (121°C) for 15 minutes. Cool to 45-50°C. If desired, the medium can be enriched with 5-10% blood or other biological fluids. Mix well and pour into sterile Petri plates.

Principle And Interpretation

Nutrient media are basic culture media used for maintaining microorganisms, cultivating fastidious organisms by enriching with serum or blood and are also used for purity checking prior to biochemical or serological testing (1,2). Nutrient Agar is ideal for demonstration and teaching purposes where a more prolonged survival of cultures at ambient temperature is often required without risk of overgrowth that can occur with more nutritious substrate. This relatively simple formula has been retained and is still widely used in the microbiological examination of variety of materials and is also recommended by standard methods. It is one of the several non-selective media useful in routine cultivation of microorganisms (3,4). It can be used for the cultivation and enumeration of bacteria which are not particularly fastidious. Addition of different biological fluids such as horse or sheep blood, serum, egg yolk etc. makes it suitable for the cultivation of related fastidious organisms. Peptone, HM peptone B and yeast extract provide the necessary nitrogen compounds, carbon, vitamins and also some trace ingredients necessary for the growth of bacteria. Sodium chloride maintains the osmotic equilibrium of the medium.

Type of specimen

Clinical samples - faeces, urine; Food and dairy samples; Water samples

Specimen Collection and Handling:

  • For clinical samples follow appropriate techniques for handling specimens as per established guidelines (5,6).
  • For food and dairy samples, follow appropriate techniques for sample collection and processing as per guidelines (3,4,7).
  • For water samples, follow appropriate techniques for sample collection, processing as per guidelines and local standards (8).
  • After use, contaminated materials must be sterilized by autoclaving before discarding.

Warning and Precautions :

In Vitro diagnostic use. For professional use only. Read the label before opening the container. Wear protective gloves/protective clothing/eye protection/ face protection. Follow good microbiological lab practices while handling specimens and culture. Standard precautions as per established guidelines should be followed while handling clinical specimens. Safety guidelines may be referred in individual safety data sheets.

Limitations :

  • Individual organisms differ in their growth requirement and may show variable growth patterns on the medium.
  • Each lot of the medium has been tested for the organisms specified on the COA. It is recommended to users to validate the medium for any specific microorganism other than mentioned in the COA based on the user's unique requirement.

Performance and Evaluation

Performance of the medium is expected when used as per the direction on the label within the expiry period when stored at recommended temperature.

Quality Control

Appearance

Cream to yellow homogeneous free flowing powder

Gelling

Firm, comparable with 1.5% Agar gel

Colour and Clarity of prepared medium

Light yellow coloured clear to slightly opalescent gel forms in Petri plates

Reaction

Reaction of 2.8% w/v aqueous solution at 25°C. pH: 7.4±0.2

pH

7.20-7.60

Cultural Response

Productivity:

Cultural characteristics observed after an incubation at 35-37°C for 18-48 hours.

Organism Inoculum (CFU) Growth Recovery
Escherichia coli ATCC 25922 (00013*) 50-100 good-luxuriant >=70%
Pseudomonas aeruginosa ATCC 27853 (00025*) 50-100 good-luxuriant >=70%
Salmonella Typhi ATCC 6539 50-100 good-luxuriant >=70%
Staphylococcus aureus subsp. aureus ATCC 25923 (00034*) 50-100 good-luxuriant >=70%
Streptococcus pyogenes ATCC 19615 50-100 good-luxuriant >=70%
Salmonella Enteritidis ATCC 13076 (00030*) 50-100 good-luxuriant >=70%
Salmonella Typhimurium ATCC 14028 (00031*) 50-100 good-luxuriant >=70%
Yersinia enterocolitica ATCC 9610 (00038*) 50-100 good-luxuriant >=70%
Yersinia enterocolitica ATCC 23715 (00160*) 50-100 good-luxuriant >=70%

Key: (*) Corresponding WDCM numbers.

Storage and Shelf Life

Store between 10-30°C in a tightly closed container and the prepared medium at 20-30°C. Use before expiry date on the label. On opening, product should be properly stored dry, after tightly capping the bottle in order to prevent lump formation due to the hygroscopic nature of the product. Improper storage of the product may lead to lump formation. Store in dry ventilated area protected from extremes of temperature and sources of ignition. Seal the container tightly after use. Product performance is best if used within stated expiry period.

Disposal

User must ensure safe disposal by autoclaving and/or incineration of used or unusable preparations of this product. Follow established laboratory procedures in disposing of infectious materials and material that comes into contact with clinical sample must be decontaminated and disposed of in accordance with current laboratory techniques (5,6).

Reference

  1. Lapage S., Shelton J. and Mitchell T., 1970, Methods in Microbiology', Norris J. and Ribbons D., (Eds.), Vol. 3A, Academic Press, London.
  2. MacFaddin J. F., 2000, Biochemical Tests for Identification of Medical Bacteria, 3rd Ed., Lippincott, Williams and Wilkins, Baltimore.
  3. American Public Health Association, Standard Methods for the Examination of Dairy Products, 1978, 14th Ed., Washington D.C.
  4. Salfinger Y., and Tortorello M.L., 2015, Compendium of Methods for the Microbiological Examination of Foods, 5th Ed., American Public Health Association, Washington, D.C.
  5. Isenberg, H.D. Clinical Microbiology Procedures Handbook 2nd Edition.
  6. Jorgensen, J.H., Pfaller, M.A., Carroll, K.C., Funke, G., Landry, M.L., Richter, S.S and Warnock., D.W. (2015) Manual of Clinical Microbiology, 11th Edition. Vol. 1.
  7. Wehr H. M. and Frank J. H., 2004, Standard Methods for the Microbiological Examination of Dairy Products, 17th Ed., APHA Inc., Washington, D.C.
  8. Lipps WC, Braun-Howland EB, Baxter TE, eds. Standard methods for the Examination of Water and Wastewater, 24th ed. Washington DC:APHA Press; 2023.
More Information
Product Name Nutrient Agar
SKU M001
Application/ Industry General Purpose
Product Type Regular
Physical Form Powder
Regulatory APHA
Origin Animal
Packaging type HDPE
References 1. American Public Health Association, Standard Methods for the Examination of Dairy Products, 1978, 14th Ed., WashingtonD.C.
2.Salfinger Y., and Tortorello M.L. Fifth (Ed.), 2015, Compendium of Methods for the Microbiological Examination ofFoods, 5th Ed., American Public Health Association, Washington, D.C.
3.Baird R.B., Eaton A.D., and Rice E.W., (Eds.), 2015, Standard Methods for the Examination of Water andWastewater, 23rd ed., APHA, Washington, D.C.
4.Isenberg, H.D. Clinical Microbiology Procedures Handbook. 2nd Edition.
5.Jorgensen,J.H., Pfaller , M.A., Carroll, K.C., Funke, G., Landry, M.L., Richter, S.S and Warnock., D.W. (2015)Manual of Clinical Microbiology, 11th Edition. Vol. 1.
6.Lapage S., Shelton J. and Mitchell T., 1970, Methods in Microbiology, Norris J. and Ribbons D., (Eds.), Vol. 3A,Academic Press, London.
7.MacFaddin J. F., 2000, Biochemical Tests for Identification of Medical Bacteria, 3rd Ed., Lippincott, Williams and Wilkins,Baltimore.
8.Wehr H. M. and Frank J. H., 2004, Standard Methods for the Microbiological Examination of Dairy Products, 17th Ed.,APHA Inc., Washington, D.C.

Clinical Laboratory Applications

1. Challenge:

A clinical microbiology laboratory receives urine, wound swab, and skin specimen samples from patients presenting with suspected bacterial infections. At the initial stage of testing, the identity of the causative microorganism is unknown, requiring a general-purpose medium capable of supporting the growth of a broad range of non-fastidious bacteria.

2. Solution:

Nutrient Agar is used as a primary isolation and cultivation medium because it provides essential nutrients without incorporating selective or inhibitory agents. Clinical specimens are streaked directly onto Nutrient Agar plates and incubated aerobically at 35-37°C for 18-24 hours.

The medium supports the growth of commonly encountered organisms such as Escherichia coli, Staphylococcus aureus, Bacillus spp., and other non-fastidious bacteria. Colony morphology, pigmentation, size, elevation, and texture are evaluated as part of the preliminary identification process.

3. Expected Outcome:

Distinct bacterial colonies become visible after incubation, allowing microbiologists to assess culture purity and select representative colonies for further testing. Follow-up procedures may include Gram staining, biochemical identification, antimicrobial susceptibility testing, or inoculation onto selective and differential media for confirmatory analysis.

Food Safety Testing Protocols

1. Challenge:

A food testing laboratory must evaluate finished food products and raw materials for microbial quality and potential contamination. Regulatory standards require routine monitoring of microbial load to assess product safety and manufacturing hygiene.

2. Solution:

Nutrient Agar is used for Total Viable Count (TVC) determination and preliminary screening of bacterial contaminants. Food samples are homogenized, serially diluted, and plated onto Nutrient Agar using pour plate or spread plate techniques.

Plates are incubated at 30-35°C for 48-72 hours under aerobic conditions.

3. Expected Outcome:

Visible colony formation allows analysts to calculate microbial counts expressed as colony-forming units (CFU) per gram or milliliter of product. Elevated microbial counts may indicate inadequate sanitation, raw material contamination, or process control failures.

Suspect colonies can be subcultured onto selective media for pathogen confirmation and further microbiological investigation.

Environmental Monitoring and Water Testing Applications

1. Challenge:

Pharmaceutical, food, healthcare, and manufacturing facilities require routine environmental monitoring to detect microbial contamination in water systems, air handling units, cleanrooms, and production surfaces before contamination impacts product quality.

2. Solution:

Nutrient Agar is incorporated into environmental monitoring programs for water testing, surface sampling, and air monitoring activities.

Water samples are filtered or directly inoculated onto the medium, while surface and air samples are collected using contact plates, settle plates, or active air samplers. Incubation is typically performed at 30-35°C for 48-72 hours.

3. Expected Outcome:

The medium supports recovery of a wide range of environmental bacteria, enabling laboratories to establish microbial baseline trends and identify contamination events.

Colony counts are compared against alert and action limits established by facility monitoring programs. Any excursions trigger investigations, corrective actions, and additional microbial identification procedures to determine contamination sources.

Educational Laboratory Protocols

1. Challenge:

Academic institutions and microbiology training laboratories require a versatile culture medium that allows students to learn fundamental microbiological techniques while observing bacterial growth characteristics in a controlled laboratory environment.

2. Solution:

Nutrient Agar serves as an introductory microbiology medium for teaching aseptic techniques, streak plate isolation, colony counting, microbial enumeration, and culture maintenance.

Students inoculate bacterial cultures onto Nutrient Agar plates and incubate them at 30-37°C for 24-48 hours. The medium's non-selective nature allows clear observation of colony development and morphological diversity.

3. Expected Outcome:

Students gain practical experience in culture handling, microbial isolation, and colony characterization.

Visible differences in colony size, shape, texture, elevation, and pigmentation help reinforce microbiological concepts while providing a foundation for advanced identification methods, selective media applications, and laboratory quality control practices.

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What is Nutrient Agar?

Nutrient Agar is a general-purpose, non-selective medium for cultivating, isolating and enumerating non-fastidious microorganisms. Because it contains no selective or differential agents, it supports unrestricted growth of most aerobic and facultative anaerobic bacteria. It is used for purity testing, bioburden determination, culture maintenance, environmental monitoring and water analysis, and allows observation of colony morphology, pigmentation and texture for preliminary identification.

What are the composition and formula of Nutrient Agar?

HiMedia Nutrient Agar (M001) contains peptone, sodium chloride, HM Peptone B, yeast extract, and agar, providing essential nutrients and a solidifying matrix for microbial growth. The formulation per litre consists of peptone 5.0 g, sodium chloride 5.0 g, HM Peptone B 1.5 g, yeast extract 1.5 g, and agar 15.0 g. HM Peptone B is equivalent to beef extract. The formula is adjusted and standardized to meet specified performance parameters, with a final pH of 7.4 ± 0.2 at 25°C.

What are the technical specifications of Nutrient Agar?

Nutrient Agar (M001): Nutrient Agar is a general-purpose, non-selective medium for cultivation of less fastidious microorganisms. It contains peptone (5.0 g/L), sodium chloride (5.0 g/L), HM peptone B (1.5 g/L), yeast extract (1.5 g/L), and agar (15.0 g/L). The final pH is 7.4 ± 0.2 at 25°C. The medium forms a light-yellow, clear to slightly opalescent gel with firm gelling comparable to 1.5% agar. Cultural performance is evaluated at 35–37°C for 18–48 hours, with good-to-luxuriant growth and ≥70% recovery for specified test organisms.

How much does 500g of Nutrient Agar make?

500g of Nutrient Agar (28g per liter) makes approximately 17.9 liters of prepared medium. In plates: (1) 90mm plates (20mL each) = ~895 plates, (2) 100mm plates (25mL each) = ~716 plates. In tubes: (1) Slants (5mL) = ~3,580 slants, (2) Deeps (10mL) = ~1,790 deeps. Cost comparison: 500g dehydrated costs significantly less than equivalent RTU plates but requires preparation time, autoclave, QC testing. For high-volume teaching labs or facilities with established media prep - dehydrated economical. For clinical/GMP - RTU preferred.

What is Nutrient Broth used for?

Nutrient Broth is simple liquid medium for cultivation of non-fastidious bacteria. Contains beef extract and peptone in water. Used for: (1) General bacterial cultivation, (2) Biomass production for testing, (3) Inoculum preparation, (4) Enrichment (non-selective), (5) Maintaining stock cultures, (6) Teaching laboratories. Less nutrient-rich than TSB or BHI. Sufficient for robust organisms (E. coli, Bacillus, Pseudomonas) but may not support fastidious organisms. Incubate at organism's optimal temperature with shaking if desired for aeration.

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