+
ward
'
s
science
5100 West Henrietta Road • PO Box 92912 • Rochester, New York 14692-9012 • p: 800 962-2660 • wardsci.com
2. Working in a clean, draft free area, wipe the work surface with isopropyl alcohol or bactericidal cleanser.
Take care to use sterile handling techniques to prevent contamination.
3. Each Petri dish consists of a wider/shallower cover, and a narrower/deeper bottom portion. Remove the Petri
dishes from the package; do not remove the covers from the dishes yet. Lay out all the Petri dishes that you will be
using, making sure the cover is on top. Re-seal the bag if it contains any plates that will not be used at this time.
4. Working on one plate at a time, carefully tilt open the cover (See Figure 1) and pour about 15 – 20 mL of liquid into
the bottom portion (it should cover about 2⁄3 of the plate's surface). Gently swirl the plate to spread out the liquid
media so that it covers the entire bottom surface of the plate. The layer should be about 3 – 4 mm deep. Once you
have enough liquid in the plate, place the top back on.
5. Allow plates to cool before use. This takes about one hour. You can use a refrigerator to speed up this process,
but do not put agar in a freezer.
6. Plates can be used to subculture bacteria or fungus once they have cooled. Unused plates can be stored in the
refrigerator for 2 – 4 weeks.
Disposition
• Unused agar plates can be disposed of in the regular trash.
• Used agar plates containing bacteria can be disposed of by one of the following methods:
• Autoclave @ 121°C for 15 minutes in an autoclavable bag (Petri dishes will melt in the autoclave—
do not autoclave unbagged).
• Use a 20% bleach solution to kill bacteria in the plate, and then dispose in the regular trash.
• Use 70% isopropyl alcohol to kill bacteria, and then dispose in the regular trash.
© 2021 Ward' s Science. All rights reserved. Rev. 2021
