What Room in the House Holds the Most Germs?

Problem:

What room in the house holds the most germs?

Hypothesis:

I predict that the room in the average house that contains the most germs is the bathroom. This is because people go to the bathroom in there and also wash their hands. It is also one of the most used rooms in the house by many different people coming from different places. If you have company, it is most likely that they will have to use the bathroom at some point.

Procedure:

• 1. Dip sterile swab in the distilled water.

  2. Swab each of the areas around the house.

  3. Put each swab into the corresponding sterile plastic bag.

  4. Swab each agar plate with the contaminated swab.

  5. Culture the bacteria colonies for three days (or as long as it takes to get enough bacteria to collect data).

  6. Count and organize the amounts of colonies for each plate.

  7. Repeat these steps for each test.

Conclusion:

During this experiment, I tested different rooms in the house to see which one held the most germs. The rooms that I tested were the living room, kitchen, bathroom, and control which was distilled water. I found that the kitchen grew the most amount of bacteria colonies. I hypothesized that the bathroom would hold the most germs because many different people go to the bathroom and wash their hands in there. My hypothesis was incorrect because looking at my data, clearly the kitchen had many more colonies than any of the other rooms. The kitchen had an average total of 116.5+ colonies, whereas the bathroom only had an average total of 14.5. Therefore, the kitchen definitely contains the most germs. I believe that my project was accurate because I made sure that I followed the same steps for each test. To improve my project, I could have tested each room more than two times to get a better average, but because of the amount of time we had, two was the maximum.

Abstract:

Last year, I conducted an experiment about seeing which soaps would kill the most germs. I wanted to go deeper in this topic so I decided to test the idea of seeing which room has the most germs. I tested my living room, kitchen, and main bathroom to see which one held the most germs. I predicted that the bathroom would have the most germs because people go to the bathroom there and also wash their hands.

I tested the three rooms - the living room, bathroom, and the kitchen. The first step that I took in conducting this experiment is dipping the sterile cotton swab in distilled water. Next, I swabbed the areas with the swabs. I then put them in sterile plastic bags and labeled them. I repeated this process for each of the rooms that I was testing twice. Now it was time to test them in the lab. I brought all of the bags with the swabs into the lab. I then got my nutrient agar plates and took out the swabs. I took them out and rubbed the dirty swabs onto the surface of the plates. Next, I taped the plate shut and labeled them. I repeated this for each room. To give the bacteria colonies a chance to grow, I cultured them under a heat lamp for three days. On the third day I went back in the lab, and counted about how many colonies there were. I categorized them into small, medium, and large colonies. This was similar to how I arranged my data last year, but this year I added another category. The estimated percent filled of the plate with bacteria colonies.

In the results of this experiment, I found that the kitchen holds the most germs. My data proves this because the kitchen had an average of 85% of the plate filled with germs. The living room which came in second had an estimated average of 11.5% of the plate filled with germs. The room that came in third with the least amount of germs was the bathroom with only an average of 6% of the plate filled. There was a clear winner of this test and the kitchen is it.

This experiment has shown me that the room with the most germs is the kitchen. This surprised me because I hypothesized that the bathroom would carry the most germs since people go to the bathroom and wash their hands in there. Clearly, my hypothesis was wrong because the bathroom plate had an average of only 6% filled with an average total of 14.5 colonies, but the kitchen with the most germs had an average of 85% filled with an average total of 116.5+ colonies. I believe that my project was accurate. This is because for each test, I made sure that I did the same thing each time. For example, I dipped the sterile swab into the distilled water and then swabbed an area of that specific room. For the second test, I made sure I didn’t swab the exact same place as I did in the first test because that spot was already wiped clean. I could have improved my project by doing more tests. This would have put together a more complex average for more accurate results. For time sake, I was only able to do two. To conclude, I believe that I have conducted a successful project.

Graphs:

Data Tables: