science fair

Which is dirtier? The septa rails or the school bathroom’s doorknob?





Anyea Jewett & Cheng-Xian Zheng Date: 1/10/08




ABSTRACT
The reason my partner and I chose this project was because we really wanted to see which was dirtier. (Septa rails or school door knobs) the reason for this is because we use these things everyday. We touch the door knobs in order to open the door to use the rest room and it is touched by so many people a day. The septa rails are also touched so many times a day. By different people and some times we are forced to touch them when the train is crowded and you need to keep balance. So we decided to test them both and see which is the dirtier.


Question: which is dirtier the septa rails or the school bathrooms door knob?

Hypothesis: the rails on a septa train will be dirtier than the school door handle because the train is open to the public and more people are exposed to it and touch it than the school’s bathroom so the septa rail will be dirtier.

Materials
. Agar dishes
. Cotton swabs
. Septa rails
. Doorknobs
. Plastic sandwich bags
. Refrigerator
. Incubator

Procedures:
1. Open agar dish
2. Open cotton swab
3. Take cotton swab and rub across the surface of the septa rail
4. Rub the cotton swab across the surface of the agar dish
5. Close agar dish and place inside a sandwich bag upside down. And label.
6. Store in refrigerator
7. Open second agar dish
8. Open second cotton swab
9. Rub the doorknob with the cotton swab
10. Rub the surface of the agar dish with the cotton swab
11. Close and wrap in a plastic bag and place in refrigerator.
12. Repeat procedures one more time for both the septa rails and doorknobs for a total of 4-agar dishes 2 septa 2 school.



Dish Number of bacterial colonies
Septa dish 1 404
Septa dish 2 197
School dish 1 180
School dish 2 280


Observations: during our experiment, I realized after the dishes were placed in the incubator the dishes had a number of bacterial colonies scattered across the surface of them. They looked like little tiny “balls” almost. I also noticed that the same bacteria that was on the Septa dish was the same on the one that was on the one for school. It was cool really. The only hard part was having to count each and every bacteria “ball” one by one.


Conclusion: In conclusion the hypothesis was correct. The rails on a septa handle are dirtier than the doorknob at school. The septa rails tended to have more bacterial colonies found than the ones for school. They had bigger numbers. For instance the septa rail one had 404 colonies, and the school doorknob 1 had 180. The septa rail had 224 more bacteria than the doorknob dish. And septa dish 2 had 280 colonies and the school dish 2 had 180 so that’s a 100-colony difference. So over all the septa rails are dirtier.