Bacteria Growing in Blood Agar Petri Dishes
Bacteria are microorganisms that grow everywhere. For this experiment we will be growing them in a specially prepared petri dishes. The Petri dishes are prepared with a gelatin-like substance containing 5% sheep's blood. This medium provides an excellent environment in which we can watch them grow.
Lets get started.
Prepared petri dishes containing already prepared agar should be refrigerated until used and always stored upside down (i.e. media in upper dish, cover on bottom). This keeps condensation which forms in the lid from dropping onto and disrupting the bacteria growing surface.
1. When ready to apply sample, let dishes warm to room temperature.
2. Apply or inoculate the dish by gently pressing onto the agar surface. Be careful to not tear the agar surface.
3. Replace cover, tape closed, and label each dish so you know the source of the bacteria. Store upside down.
4. Let grow in warm location preferably 100°F. Do not place in direct sunlight. You will start to see growth within a couple of days. They may also start to smell.
This sample is after three days of growth.
5. Make observations and keep a record of what you see growing in each dish. You can conclude to which objects contained the most bacteria.
6. You can also perform a second experiment by testing different bacterial
Warning!
Most bacteria collected in the environment will not be harmful. However, once they multiply into millions of colonies in a petri dish they become more of a hazard. Be sure to protect open cuts with rubber gloves and never ingest or breathe in growing bacteria. Growing petri dishes should be kept taped closed until your experiment is done. Then you should safely destroy the fuzzy bacteria colonies using household bleach.
Blood Agar Peri Dishes are sold individually or packs of 10. Blood Agar Dishes are perishable, and will be shipped next day air.