More research on agar and bacteria culture

http://www.sciencebuddies.org/science-fair-projects/project_ideas/MicroBio_Agar.shtml

http://www.stevespanglerscience.com/experiment/00000165

General information about agar:

1, Chemically, agar is a polymer made up of subunits of the sugar galactose, and is a component of the cell walls of several species of red algae that are usually harvested in eastern Asia and California.

2, Agar's chief use is as a culture medium for various microorganisms, particularly for bacteria

3, Agar is preferred over regular gelatin for culturing bacteria because agar will not be degraded (eaten) by bacteria. Also, it is firmer and stronger than gelatin. 

" For students growing bacteria at home without the supervision of a teacher (for example, investigating bacteria growth at various places around the house), it's important to use an agar formulation that does not preferentially grow one kind of bacteria over another. The worst case would be one that preferentially grew pathogenic bacteria. Therefore, we recommend a plain nutrient agar, of which LB agar is a subtype.There are many different suppliers for LB agar. Because some suppliers will not sell to students directly, you may have to have your teacher order for you. If you are doing a project that involves inoculation and plate streaking, we highly recommend conducting the experiment at a school lab under teacher supervision. "

Preparing bottled agar and plates
Although pre-poured agar plates are available, one can make agar plates from tablet, powdered, or bottled agar by following a few simple instructions. Agar kits usually come with detailed instructions on how to prepare plates, and below are sample procedures for reference. When in doubt, be sure to clearly read the instructions and ask for help if needed (either consult a teacher or call the technical help line of the agar kit supplier). 


I think I will be using bottled agar or, if possible, pre-poured plates:

"Preparing Bottled Agar:

• Loosen the bottle cap, but do not remove the cap while heating.
• Warm the agar bottle in a hot water bath or in the microwave until it becomes liquid.
• After opening the cap, pass the neck of the agar bottle through a flame to sterilize it. Do not lose the cap!
• While pouring the agar, open the Petri dish lid as little as possible, hold it at an angle, and make sure the lid is kept directly over the Petri dish.
• Pour enough melted agar into each sterile plastic Petri dish to cover 1/8" of the bottom. Cover the lid of the Petri dish immediately.
• Place agar plates on a counter top to cool and set. Agar medium will set like stiff gelatin at room temperature.
• Pass the neck of the agar bottle through flame again before applying the cap.

Preparing Pre-Poured Plates: If plates have been refrigerated, set them out and allow them to warm to room temperature.

Storing agar plates: 


Storage: Stack agar plates upside down in the refrigerator. Do Not Freeze! The purpose of placing the plates upside down is to prevent condensation from dripping down onto the agar surface which could then facilitate movement of organisms between colonies.


About the incubator:
I will ask my Mother to take my plates to her lab for incubation and will proceed with observations at her lab. So the incubator is settled.

About the transfer of bacteria by contact: 
"
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. Caution - do not allow bleach to touch your skin, eyes or clothes. It will burn!"