Which household surface produces the most amount of bacteria colonies?
My hypothesis is that the entrance doorknob contains the greatest amount of bacteria/bacteria colonies. I have been fascinated with bacteria and microorganisms ever since a health seminar my father once took me to. I hoped to achieve the fact that people in their domicile that bacteria does exist and can be dangerous, and we should be extremely careful of our hygienic state because of the things we touch. One fact that comes to mind are coins. Coins are known as one of the dirtiest things to exist due to mix of bacteria from variety of people.
My experiment was done with 8 Petri dishes, 3 25"x30" newspaper sheets, 10 cotton swabs, 18 oz of petroleum jelly, have a cup of agar which should be in a jar with a non metal lid, 460 watts microwave and a timer.
1. First take the jar with agar and heat it for 2 minutes in the microwave.
2. Evenly pour in the 8 Petri dishes.
3. Take the lids off of the PDs (Petri Dishes) and let the agar cool in them into a jello like substance.
4. Put PDs lids' on.
5. Apply very thin layer of petroleum jelly on doorknob.
6. Use one cotton swab to dab in the doorknob a few times.
7. Gently lift two lids and lightly touch cotton swab various places.
8. Close the lids and label them DK 1 and DK 2.
9. Repeat steps 5 through 8 for kitchen counter and carpet.
10. Label the last two PDs Control 1 and Control 2.
11. Record observations 4-5 times 3 days after the experiment.
Independent = The household surfaces
Dependent = Number of bacteria colonies.
Control = Untouched agar dish.