Experiment No 5.
Preparation of Nutrient Agar Medium
REQUIREMENTS
Measuring cylinder, test-tubes, pH strip, non-absorbent cotton, filter paper, funnel, conical flask,
round bottom flask etc.
COMPOSITION OF NUTRIENT AGAR MEDIUM:
COMPOSITION:
Peptone (1%), Lab lemco (1%), Sodium chloride (1%), Agar (1.5-2%), Distilled water (100mL)
PROCEDURE:
The ingredients are dissolved by warming the contents of the flask gently with stirring
with a glass rod until a clear homogenous solution is formed.
Adjust the pH 6.6 to 6.8 and observe the pH by either a pH strip or a pH meter. Adjust
final volume, if required, and filter it.
After obtaining homogenous dispersion, fill it in a test tube. Depending on requirement,
test tubes are filled from 2 to 5mL in a test tube.
If you’re required to make Agar slant, fill 2-5mL Nutrient Agar in the test tube.
If you’re required to make nutrient broth, fill 5-7mL.
If you’re required to make nutrient Agar, fill 8-10mL in each test tube.
Cork test tubes using non-absorbent cotton.
Sterilize this medium in autoclave at 15 PSI for 20 to 30 minutes.
Take care while accurately measuring the pH of sterilizing medium.
Generally, Nutrient Gar is added to Nutrient broth to solidify the medium. In autoclave, it
will melt at approximately 99°C. It solidifies before 40°C. Melted agar remains in the
molten state between 40 to 45°C, which should be inoculation temperature.
It is clear when hot, but slightly opalescent on cooling.
NOTE:
Students can paste various images of their group while performing practical work, prepared
plates, jars or bottles of marketed products of media etc.
Preparation of Nutrient Agar Medium
REQUIREMENTS
Measuring cylinder, test-tubes, pH strip, non-absorbent cotton, filter paper, funnel, conical flask,
round bottom flask etc.
COMPOSITION OF NUTRIENT AGAR MEDIUM:
COMPOSITION:
Peptone (1%), Lab lemco (1%), Sodium chloride (1%), Agar (1.5-2%), Distilled water (100mL)
PROCEDURE:
The ingredients are dissolved by warming the contents of the flask gently with stirring
with a glass rod until a clear homogenous solution is formed.
Adjust the pH 6.6 to 6.8 and observe the pH by either a pH strip or a pH meter. Adjust
final volume, if required, and filter it.
After obtaining homogenous dispersion, fill it in a test tube. Depending on requirement,
test tubes are filled from 2 to 5mL in a test tube.
If you’re required to make Agar slant, fill 2-5mL Nutrient Agar in the test tube.
If you’re required to make nutrient broth, fill 5-7mL.
If you’re required to make nutrient Agar, fill 8-10mL in each test tube.
Cork test tubes using non-absorbent cotton.
Sterilize this medium in autoclave at 15 PSI for 20 to 30 minutes.
Take care while accurately measuring the pH of sterilizing medium.
Generally, Nutrient Gar is added to Nutrient broth to solidify the medium. In autoclave, it
will melt at approximately 99°C. It solidifies before 40°C. Melted agar remains in the
molten state between 40 to 45°C, which should be inoculation temperature.
It is clear when hot, but slightly opalescent on cooling.
NOTE:
Students can paste various images of their group while performing practical work, prepared
plates, jars or bottles of marketed products of media etc.
