BISC209: Pour Plates

Pouring of Agar plates

1. Place the Petri plates to be poured right side up in front of you (if many plates are to be poured, you may want to set them up in stacks of three).

2. Obtain a bottle of melted and cooled (45°-50°) agar from the water bath. Carefully wipe the adhering water from the bottle so that, when you tip the bottle, this contaminated water will not run into the plate. Light a Bunsen burner and properly adjust the flame. Remove the cap of the bottle as illustrated in Figure A-3. Lightly pass the lip of the bottle through the flame to burn off any adhering dust. The lip of the bottle should already be sterile from the autoclaving procedure. Pour 10-15 mls of molten agar into each plate (with practice you will quickly learn how to judge the proper amount by eye), being careful to prevent the drip on the lip from running down onto the contaminated outer glass. Carefully slide the plates to an undisturbed area of the bench to solidify.

Figure A-6: (a) Removal of a bottle cap aseptically. Note how the rest of the hand is free to manipulate a pipette or plate lid. (b) Pouring agar into a plate. Note how the lid shields the agar from airborne contamination.