Step 1. Using a sterile loop, streak cultures (liquid broth or isolated colonies picked from plates) over one-fourth of the surface of an agar plate. Then flame the loop as described on the preceding page.
Swabs containing an inoculum should be rolled over a small area of the agar surface to deposit the inoculum and then distributed over one-fourth of the surface with a sterile loop. The swab can then be used to prepare a stain or discarded.
Step 2. Air cool a flamed loop or cool it by touching an unstreaked area of agar on the same plate.
Step 3. Pass the cooled loop three or four times over the initial streaked portion of the plate. Streak it, without overlap, to the next quadrant.
Step 4. Flame the loop and allow it to cool as described above in Step 2.
Step 5. Pass the loop over the streaked portion of the second quadrant two or three times and then streak the material without overlapping over the third quadrant of the plate.
Step 6. Repeat Step 5 to streak the last quadrant.
Most bacteria do not move appreciably from the sites of inoculation but give rise there to clones of bacteria called colonies. Isolated colonies should arise in the third and fourth quadrants depending on the concentration of bacteria in the initial inoculum.