Published: 26th Feb 2025, 12:02

Hello Microbiologists, remember the first agar that you prepare, the yellowish jelly. Yes, you are thinking right; we are talking about that general-purpose media, Nutrient Agar. Let’s decode the composition of Nutrient Agar. The first Culture Media composition we learnt in this journey of being a Microbiologist.

It consists of

Let’s Decode Nutrient Agar

Let’s break the name into two: Nutrient & Agar. So start with the simpler one that is Agar.

Agar

Agar is a solidifying agent that gives a stable surface to organisms to grow in the Culture Vessel. It aids in the observation of colony morphology.

this unbranched polysaccharide extracted from red algae species such as Gelidium. It lacks nutritional value and melts at approximately 100°C temperature and easily solidifies at room temperature. Hence, it does not affect bacteria growth and is perfect to work with at room temperature. It remains intact and doesn’t break down by bacteria. It can be used in plates, bottles, and slants.

But do you know how microbiologists get to know about this? Click and know

Nutrient Broth

Nutrient Broth remains in liquid formulation at room temperature due to the lack of Agar. It is usually used to maintain the stocks of microorganisms or to grow fastidious organisms. It can also be enriched with blood, serum, sugar, etc., for special purposes.

Composition difference of Nutrient Agar & Nutrient Broth

Now the term Nutrient, so nutrient in Nutrient Agar is not just one thing; it comes from various ingredients, and they are.

Peptone

It serves as the primary source of nitrogen for bacterial growth. It provides essential amino acids, proteins, and peptides that are necessary for the growth of bacteria. Generally, Peptone is produced by enzymatic digestion of animal proteins, but here’s a do-you-know point. At TM Media, plant-based Peptone is also available.

The next nutritional ingredient is Beef Extract

It serves as the primary source of carbon, which plays an essential role in the formation of carbohydrates. Carbohydrates are the energy source for bacteria. It also contains other growth-enhancing components like vitamins, trace minerals, organic compounds, and salts.

The other ingredient is Sodium Chloride

Nutrients in the medium and environment in the lab play an important role in supporting the growth of bacteria. And that’s why Sodium Chloride is added to the medium to maintain the osmotic equilibrium of the medium. It prevents the change in pH of the medium during growth. The final pH of Nutrient Agar is 7.4 at 25°C.

Yeast Extract

It consists of the cell contents of yeast without the cell walls and serves as a nitrogen source. It also provides some of the essential Amino Acids.

All these ingredients help in the growth of a wide range of bacterial and fungal species. Hence, Nutrient Agar is one of the widely used Culture Media. It can be used with or without agar as solid or liquid media depending on the user’s needs.

For some specific microorganisms or to study specific characteristics of microbial specie this media can be enriched with media supplements for example to grow fastidious organism it can be enriched with Blood, Egg Yolk, etc. It is an ideal medium for teaching and demonstration purposes, as it allows longer survival of microbial cultures at room or ambient temperature. It is comparatively less nutritive; hence, the, the chances of overgrowth are delayed with this medium.

At TM Media, Nutrient Agar is available in various formats such as Powder, Prepared Plates, Bottles, Slants. Click to check now.