When Streaking a Plate the Loop Should Be Flamed?

Place a loopful of the culture on the agar surface on the area 1. Flame the loop and cool it for 5 seconds by touching an unused part of the agar surface close to the periphery of the plate, and then drag it rapidly several times across the surface of area1. Remove the loop and close the Petri dish.

Why must you flame the loop between streaks?

This is done by having the loop pick up only a small amount of bacteria from the previous quadrant's streaks. Flaming the loop between streaks ensures that the loop starts clean and that only this small amount of bacteria is used to inoculate the next quadrant.

Why should the loop not be over flamed?

A loop or needles is sterilized by inserting it into a Bunsen burner flame until it is red hot. This will incinerate any contaminating organisms that may be present. Allow the loop to cool completely beefore picking up inoculum.