Which surface in my house has the most bacteria?

I will test the amount of bacteria on different surfaces in my house using petri dishes. The different surfaces where I will test out the bacteria levels are going to be wooden floor, carpet and windows.
Talha Amin
Grade 8

Hypothesis

My hypothesis is that the carpet surface will have the most bacteria and spore growth, because it has little crevices where the bacteria can hide. The way carpet gets cleaned is by vacuuming it, since there are crevices in the carpet, it is hard to get all the bacteria out with any vacuum. The carpet also has bacteria that  is growing in it and if you do not wash your carpet regularly then there will be a lot of bacteria.

 

Research

  • https://karmacarpetcleaning.com/beware-your-rugs-are-filled-with-bacteria-and-other-contaminants/ I read this article to help me with my hypothesis. One of the different surfaces that I am testing the bacteria on is the carpet. This article is about how your carpet attracts a lot of bacteria and how that bacteria can also grow in your carpet. There are multiple ways that bacteria can get into your carpet, like food crumbs, dirt, and grime from other places. Bacteria can also get stuck in the carpet, which makes bacteria live in the carpet. Our carpets get pretty dirty, from our feet to our food crumbs. I think out of all the surfaces I am going to test, the carpet will be the one with the most bacteria.
  • https://glassed.vitroglazings.com/topics/glass-decontamination: Another article I read is about glass and how bacteria are attracted to glass surfaces. It talks about how easy it is to clean glass with chemical spray and how to know when the glass is dirty or clean. This is because glass is clear, and when a glass sample is clean, you can see through the glass crystal clear. Also, if you make your finger touch the glass, you can sometimes see your fingerprint. If your glass has some dust or dirt, it will be easy to see; therefore, most people focus on cleaning their windows. With all that information I assume that the window will be the cleanest.
  • https://greyspaceflooring.co.uk/blog/are-wood-floors-hygienic/ : This article talks about how wooden floors are way cleaner than carpet because the carpet has few crevices where bacteria can hide, while the wooden floor is flat, so it is easy to clean with a cloth. The carpet is also harder to clean because the vacuum cannot reach that deep in the carpet. Wooden floors are smooth surfaces where it is hard for bacteria to hide; however, the wooden floor probably gets a lot of bacteria from people’s feet and other things.
  • We humans cannot see bacteria with the bare eye so this information is critical for my experiment, with how we use the different surfaces and what materials they are made up of helps us conclude which surface has the most bacteria. 
  • You need to understand another challenge in the research that could change the results, which is that in some areas on the surfaces might have more bacteria than others because it could be because it has been used more.
  • Dents in the wooden floor could be a “home” for the bacteria to live.
  • One thing to take in account in this experiment is, when was the last time that surface had gotten cleaned and how goodly.

Variables

  • Controlled Variable: The controlled variables in this experiment are the amount of time and the heat bacteria will grow in. The amount of time the bacteria will grow is one day.
  • Manipulated Variable: The manipulated variable in this experiment will be the different surfaces I will be getting the bacteria from. Different surfaces will be: Wooden floor, carpet and windows. 
  • Responding Variable: Will be the amount of spores that grows after adding  the bacteria in the petri dishes, the more spores that grow in the petri dish the more bacteria on that surface.

Procedure

  1. First I will be using cotton to swipe multiple surfaces to get a sample.
  2. Then I will swipe those samples on the petri dish.
  3. I will let the bacteria grow for 3 days.
  4. Then I will check up on all the petri dishes every day.
  5. After the 3 days I will compare my results with my hypothesis.

 

Observations

Day 1:  I gave the petri dish 1 day to grow then I checked up on them:

The bacteria started to grow after 1 day, like the small little white circles, and in some places there are yellow spots.

The bacteria still started to grow, and you could see small white spots, but less bacteria grew compared to the carpet.

A lot of bacteria grew on this plate, and there are more yellow spots on this one. I think currently this plate has the most bacteria. 

Day 2:  I gave the petri dish 2 days to grow then I checked up on them:

Nothing really changed with day 2. I did not see that much difference.

Final day: This is the final results of the bacteria growth: 

 This is the last day, and there was not that much change in the bacteria's growth after one day. The surface with the most bacteria was the wooden floor, followed by the carpet and the window.

 

Analysis

There was not that much bacteria growth after the first day. There were a lot of white circles and whiteness. There were also yellowish spots in some places. What I also noticed was that the places with less bacteria had white circles, but in the places with a lot of bacteria, the white circles combined, making it look like a bunch of white shapes.

 

 

Conclusion

My hypothesis was that the carpet would have the most bacteria because of how easily bacteria can get in the carpet and how hard it is to get out. My hypothesis was proven wrong. The results came to be that the carpet was cleaner, and I think it is because I did not get the samples from inside the crevice of the carpet; I got my samples from the top. Another reason that my hypothesis could be wrong is because fewer people have stepped on the carpet compared to the wooden floor prior to my experiment. Another reason could have been that the area was contaminated with outdoor shoes.

 

 

Application

My experiment's purpose was to test which surface was cleaner and the reasoning behind it. Even though I did the experiment in my house, the results are probably the same. This information is very important in our day-to-day lives. Let's say you dropped an apple on each of these surfaces. These results can help you know which apple is cleaner.

 

 

Sources Of Error

A source of error in this experiment could be how many times I swiped each cotton swab on the multiple surfaces to get each sample. Another source of error would be which area I swiped because some areas on certain surfaces have more bacteria than the other parts. I could have also touched the sample before letting the bacteria grow.

 

Acknowledgement

I acknowledge these sources that have helped me with my experiment:

  • Karma Cleaning 
  • Grey Space Flooring
  • Vitro Glass

I would like to acknowledge Amazon for delivering my supplies on time.

I would like to acknowledge this video that helped me use a petri dish properly:https://www.youtube.com/watch?v=bQPUXUULAo0