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How to Sterilize an Agar Dish

Agar is a gelatinous substance derived from red seaweeds and used to cultivate microbiological specimens such as molds and bacteria. A flat plastic or glass petri dish is usually lined with a layer of agar that is then exposed to micro-organisms and then sealed. The exposed petri dishes are then left alone for periods of time, until sufficient numbers of organisms have cultivated on the agar. In order to assure that only the intended micro-organisms breed in the agar, you must sterilize the petri dishes before use.

Things You'll Need

Antibacterial soap
Stove
Pot
Tongs
Bleach

Instructions

Sterilizing plastic petri dishes.
- 1
  Wash the glass petri dishes with antibacterial soap and warm water, making sure to remove all traces of organic material. Rinse the glass petri dishes thoroughly.
- 2
  Place the petri dishes in a pot of water, and bring the water to a boil on a stove.
- 3
  Allow the petri dishes to sit in boiling water for at least 15 to 20 minutes. Use tongs to carefully remove the glass petri dishes from the boiling water, and shake of any excess water.
- 4
  Assemble the tops and bottoms of the glass petri dishes, and then place them in a sterile environment.
Other Sterilization Method
- 5
  Mix 1 tablespoon of bleach with a quart of water.
- 6
  Soak the plastic petri dishes in the diluted bleach for 30 minutes.
- 7
  Remove the plastic petri dishes from the diluted bleach and rinse them with water thoroughly.
- 8
  Shake off any excess water from the plastic petri dishes and then assemble their tops and bottoms. Place the sterilized plastic petri dishes in a sterile environment.

Animals & Science