Tuesday, June 30, 2020

Preparation of Nutrient Agar Plate


Aim

To prepare nutrient agar plates for cultivation of bacteria.

Principle

Nutrient Agar is a basal solid medium which support the growth of a variety of common heterotrophic bacteria. It is one of the general purpose media. It is used for the isolation of mciroorganisms and to do some sensitivity tests. The pH of the medium is 6.8-7.2. The neutral range of pH range aids the growth of a wide variety of microorganisms. The nutrient agar media consists of:

Peptones- They are protein hydrolysate prepared by partial proteolytic digestion of meat, casein, soya meal, gelatin and other protein sources. They serve as source of carbon, energy and nitrogen.

Beef Extract- They are prepared by extracting water soluble components of beef tissues. It is a complex mixture of proteins, carbohydrates, lipids and other biochemical constituents.

Yeast Extract- An aqueous extract of yeast cells containing vitamins and other growth factors.

Agar agar- A complex polysaccharide extracted from the algae Gellidium. It is a solidifying agent with gelling temperature of 45oC and melting temperature of 95oC. It is not a nutrient source and is resistant to enzymatic dehydration.

 Materials Required

Beef extract, Yeast extract, peptone, sodium chloride, agar agar, distilled water, conical flask, weighing machine, measuring cylinder, heater.

 Procedure

1. Beef extract, yeast extract, peptone and sodium chloride were weighed to the required amount and added to a known volume of water.

2. They were mixed well and dissolved.

3. pH was adjusted to 6.8-7.2.

4. The agar was weighed and added to the medium and dissolved by boiling.

5. After the agar was dissolved properly, the medium was poured to conical flask or tubes in the required amount.

6. These were plugged with cotton and autoclaved at 121oC at 15 lbs pressure for 20 minutes.

7. The medium was then cooled to hand bearable temperature and poured into sterile petri plates.

 Result

A nutrient agar plate was prepared.


 

 

 

 



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