Growing Bacteria in Petri Dishes

Getting Started....

What you need:
1.Petri dishes containing agar medium and nutrients
2.Bacteria from hands, sink, desk, etc
3.Wax pencil for labeling dishes
4.Masking tape for sealing the dishes
5.Bleach for disposing of the bacteria

What to do:
1.Prepared petri dishes 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.
2.When ready to use, let dishes come to room temperature before taking samples (about one hour).
3.Without tearing the agar surface, inoculate the dish by gently pressing fingers, finger nails, coin, etc onto agar surface. (Direct contact of lips or tongue is NOT a good idea.)
4.Replace cover on dish, tape closed, and label each dish so you know the source of the bacteria. Store upside down.
5.Let grow in undisturbed warm location, ideally in an environment around 100° F (37° C) - not in sunlight or on a heating register.
6.You should see growth within a couple of days. The dishes will start to smell which means the bacteria are growing.
7.Make observations and keep records of what you see growing in each dish. Can you make any conclusions about what objects had the most bacteria?
8.Before disposing of dishes in the trash the bacteria should be destroyed. Pour a small amount of household bleach over the colonies while holding dish over sink.

In this type of experiment, bacteria is transferred directly to the prepared petri dish via direct contact. You can test the effectiveness of different soaps by treating different petri dishes with "dirty" hands before washing and "clean" hands after washing. Or, you can press a variety of common objects like coins, combs, etc. on different plates and compare the bacteria growth that results. We will be doing this and looking at was of mutating the grow of said bacteria. Another more appropriate manner of collecting initial bacteria would be to use sterile swabs to collect the specimens.

Steps for this procedure where provided by this website:
http://secure.sciencecompany.com/Bacteria-Growing-Experiments-in-Petri-Dishes-W54C659.aspx