This document outlines a procedure for isolating microorganisms from a sample using the pour plate method. The aims are to isolate and obtain pure cultures of microorganisms. The principle involves diluting the sample and mixing it with warm agar which is then poured into petri dishes to form individual colonies after incubation. Colonies are then transferred to fresh media for identification. The procedure involves preparing and sterilizing media, diluting the sample, pour plating the dilutions, incubating, and recording results to determine the number of viable microorganisms present.

2. AIM
To isolate microorganisms from the
sample
To get pure culture of microorganisms

3. PRINCIPLE
 Pour plate is a rapid quantitative isolation method
 This method is used to isolate bacteria, fungus, and
actinomycetes
 Original sample is diluted several times to thin out the population
sufficiently
 The most diluted sample is mixed with warm agar and poured
into petriplates
 After the agar solidifies and forms individual colony
 The total number of colonies equals to the number of viable
microorganisms
 Colonies were transferred on fresh media for identification

4. MATERIALS REQUIRED
 Test tubes with 9ml of diluents
 Cotton
 Autoclave
 Hot air oven
 Water bath
 Nutrient agar
 PDA medium
 Petri plates
 Pipettes

5. PROCEDURE
1) Prepared nutrient agar and PDA medium and sterilize at 121o C for 15
minutes
2) Dilute the sample upto 10-7
3) Add 1ml of sample from the 10 3 to the petri plate and label them
4) Pour the medium into sample added petriplates
5) Rotate the petri plates clockwise and anticlockwise direction and allow
it to solidify
6) Similiarly perform pour plating for other dilution from 10 -4 to 10 6
7) Incubate all the nutrient agar plates at 37o C for 24 hours
8) And incubate PDA plates at 25 – 30o C for 48 hours and record the
result

6. ADVANTAGES & DISADAVANTAGES
ADVANTAGES DISADVANTAGES
Need large volume of sample than
other methods
Heat sensitive organisms are
destroyed with melted agar
Allow the growth of the micro
aerophiles beneath the surfaces of
the medium
Some colonies are formed beneath
the surface of the agar, these
colonies are not satisfactorily used for
identification

7. RESULT
Individual colonies are noted
Calculated the number of bacteria
present in the sample