1.     Purpose:-                         

                   To describe the procedure for the streak plate inoculation for the isolation of discrete
            colonies / pure cultures.

2.     Scope:-

                     This procedure is applicable to study the morphological & biochemical characteristics of different microbial cultures.

3.     HSE Statement:-

Gloves And Face mask should be use during test.
4.     Responsibilities:-

                               i)      Manager Quality Control is responsible to ensure that procedure & formats are followed entirely as approved.
                             ii)       Microbiologist is responsible to perform the test.

5.     Materials:-

            5.1 Agar medium
5.2 Inoculation wire loops.
5.3 Bunsen burner.
5.4 Sterile Petri plates & beakers.
5.5 70% IPA Solution.

6. Definitions:-

      6.1 Culture:-
                     Population of microorganisms cultivated in an artificial growth medium. A pure culture is
            grown from a single cell; a mixed culture consists of two or more microbial species or strains
            growing together
6.2 Streak plate:-
                       A Petri dish of solid culture medium with isolated microbial colonies growing on its   surface, which has been prepared by spreading a microbial mixture over the agar surface, using an inoculating loop. BPL uses a modification of the Miles-Misra technique.
6.3 Coccoid:-
6.4 Coccus:-
                    Spherical bacterial cells
6.5 Inoculate:-
                                To transfer a liquid, product or micro-organism from one container or agar medium to

7.Flow Chart:-

8. Description:-
8.1 Principle:-
            In nature microbial populations don’t segregate themselves by species but exist with their mixtures of many other cell types. In the laboratory these populations can be separated into pure cultures. These cultures contain only one type of organism and suitable for the study of their specific morphological and biochemical properties.
The techniques commonly used for the isolation of discrete colonies / pure cultures initially require that the number of organisms in the inoculums be reduced. For this purpose streak plate, spread plate or pour plate techniques are used.
The streak plate method is a rapid qualitative isolation method. It is essentially a dilution technique that involves spreading a loopful of culture over the surface of an agar plate.
8.2 Procedure:-
8.2.1 Flame and cool the wire loop. Place a loopful of culture on the surface of agar in area “A” as shown in annex – 01 and drag it rapidly several times (3 to 4 times) across the surface of area “A”.
8.2.2 Reflame and cool the wire loop and turn the Petri dish through 90˚, then touch the loop to a corner of
the last streak of the culture on area “A” and drag it several times across the agar in area “B”.
8.2.3 The loop should never enter in area “A” again.
8.2.4 Reflame and cool the loop, again turn the Petri plate 90˚ and then drag the culture from a corner of area “B” across area “C”, using a wide streaker.
8.2.5 Again don’t let the loop touch previously streaked area.
8.2.6 The flaming of the loop at the point indicated, is to effect the dilution of the culture so that pure organisms are streaked in each area resulting in the final desired separation.
8.2.7 Incubate streaked plates at 30 – 35 ˚C for 24 – 48 hours.
8.2.8 See annex – 01 for further details.
8.2.9 Study the isolated microbes under the microscope for their morphological character and determine their biochemical properties by staining procedures

ANNEX – 01
 Streak Plate Inoculation Procedure


 9. Record:-

10. Reference:-
               United States Pharmacopoeia 35

11. Distribution:-

This SOP has to be distributed in below mentioned Departments:-

Sr. NO
Distributed to
Quality Control Department

Quality Management Department


12. Revision History:-
Date                                        Changes