DATE: 19/08/2022
EXPERIMENT NO: 1.3
POUR PLATE
AIM:
To isolate colony bacteria and to count the number of colony present in liquid specimen.
PRINCIPLE:
Pour plate method is usually the method of choice for counting the number of colony
forming bacteria present in liquid specimen. In this method fixed amount of inoculum
(1ml) from a sample is poured into the test tube containing molten cooled agar and mix
well. Then it is poured into petri dish after the solidification of agar. Plate is then
inoculated and incubated at 37°C for 24 hours. Microorganisms will grow on surface
and within medium. Colonies that grow within the medium generally are small in size
and maybe confluent, the few that grow on agar surface are of same size and
appearance as a colony forming unit (CFU). The number of microorganisms present in
particular test sample is determined using formula.
CFU/Ml = No: of colonies * Dilution factor/Volume of samples (mL)
For accurate counts, optimum count should be within a range of 30-300 colonies and in
countable plate a series of dilution should be plated. The pour plate method of
countaing bacteria is more precious than the streak plate but on average it will give a
lower count as heat sensitive microorganisms may die when they become very hot
under molten agar medium.
USE OF POUR TECHNIQUE:
The pour plate technique can be used to determine the number of microbes/mL in a
specimen. It has the advantage of not requiring previously prepared plates, and is often
used to assay bacterial contamination of food stuffs.
LIMITATION OF POUR PLATE TECHNIQUE:
Loss of viability of heat sensitive organism coming into contact with hot agar.
Embedded colonies are much smaller than those which happen to lie o surface.
EXPERIMENT NO: 1.3
POUR PLATE
AIM:
To isolate colony bacteria and to count the number of colony present in liquid specimen.
PRINCIPLE:
Pour plate method is usually the method of choice for counting the number of colony
forming bacteria present in liquid specimen. In this method fixed amount of inoculum
(1ml) from a sample is poured into the test tube containing molten cooled agar and mix
well. Then it is poured into petri dish after the solidification of agar. Plate is then
inoculated and incubated at 37°C for 24 hours. Microorganisms will grow on surface
and within medium. Colonies that grow within the medium generally are small in size
and maybe confluent, the few that grow on agar surface are of same size and
appearance as a colony forming unit (CFU). The number of microorganisms present in
particular test sample is determined using formula.
CFU/Ml = No: of colonies * Dilution factor/Volume of samples (mL)
For accurate counts, optimum count should be within a range of 30-300 colonies and in
countable plate a series of dilution should be plated. The pour plate method of
countaing bacteria is more precious than the streak plate but on average it will give a
lower count as heat sensitive microorganisms may die when they become very hot
under molten agar medium.
USE OF POUR TECHNIQUE:
The pour plate technique can be used to determine the number of microbes/mL in a
specimen. It has the advantage of not requiring previously prepared plates, and is often
used to assay bacterial contamination of food stuffs.
LIMITATION OF POUR PLATE TECHNIQUE:
Loss of viability of heat sensitive organism coming into contact with hot agar.
Embedded colonies are much smaller than those which happen to lie o surface.
