Nutrient Agar: Composition, Preparation and Uses

Nutrient Agar as one of the several non-selective general purpose media useful in routine cultivation of bacteria which are not particularly fastidious. It can be enriched with  horse or sheep blood, serum, egg yolk etc or other biological fluids for the culture of fastidious microorganisms and also used for maintaining microorganisms growth. Nutrient agar produces colonies without the risk of overgrowth

What are typical ingredients for general nutrient agar?

Nutrient agar is made up of  Peptone (protein),Sodium chloride, yeast extra and the solidifying agar.Adjusting the pH of the medium is also very important.

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

The above 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.

What is the principle of nutrient agar? 

• Yeast extract, Peptone and HM peptone B provides the nitrogen compounds.
• It also contains Vitamins,energy and some trace ingredients which are needed for bacteria growth.
• The presence of Sodium chloride is to maintain the medium's osmotic balance.

What types of specimen can be inoculated on Nutrient Agar?

Nutrient agar is a general Purpose media meaning almost all specimen can be used on this media. The most commonest specimens are :

• Biological specimens
• Food and dairy samples
• Water samples
• Soil samples

What is the appearance of nutrient agar?

Powdered Form : Cream to yellow homogeneous free flowing powder

After preparation : In Petri plates, it appears light yellow clear to slightly opalescent gel forms at a pH of 7.20-7.60

What Bacteria grows on nutrient agar and characteristics?

The following bacteria was observed growing on Nutrient agar after an incubation for 18-48 hours after  at 35-37 ° C.

Organism	Growth
Pseudomonas aeruginosa	good-luxuriant
Escherichia coli	good-luxuriant
Staphylococcus aureus	good-luxuriant
Salmonella Typhi	good-luxuriant
Streptococcus pyogenes	good-luxuriant
Salmonella Enteritidis	good-luxuriant
Yersinia enterocolitica	good-luxuriant
Salmonella Typhimurium	good-luxuriant

How do we dispose Culture media?

• You must ensure the safe disposal of used or unusable culture media by autoclaving and/or incineration.
• The laboratory protocols developed for disposing of infectious materials and materials that come into contact with the clinical sample must be decontaminated and disposed of in compliance with current laboratory techniques.

Where can you Buy Nutrient Agar (Useful Links)

• HiMedia M001-100G Nutrient Agar, 100 g from Amazon
• Nutrient Agar Kit, Includes Nutrient Agar Dehydrated, 10 Sterile Petri Dishes with Lids & 10 Sterile Cotton Swabs by Seaweed Solution Laboratories from Amazon
• HiMedia M001-500G Nutrient Agar, 500 g by HiMedia Laboratories from Amazon

Reference

1. www.mltgeeks.com

• Tweet
• Share
• Share
• Share
• Share