Abstract
If you'd rate yourself high on the bacteriophobia scale, just keep on scrolling down to the next project. Bacteria are all around us, and normally our body's defenses keep us blissfully unaware of them. If you don't mind finding out where they're lurking in your house, then you might find this project interesting.Summary
Areas of Science
Difficulty
Time Required
Long (2-4 weeks)
Prerequisites
Familiarity with sterile laboratory technique is a big plus.
Material Availability
Specialty items
Cost
Average ($50 - $100)
Safety
Standard precautions for handling bacterial cultures.
Credits
Andrew Olson, Ph.D., Science Buddies
Sources
This project is based on:
- Toy, M.A., 2003. To Clean or Not Too Clean? California State Science Fair Abstract. Retrieved October 27, 2006.
Objective
The goal of this project is to determine which kitchen cleaning aid is most susceptible to contamination by bacteria, and which disinfectant method cleans most effectively.
Introduction
Bacteria are all around us, and our immune system is generally good at keeping them in check and preventing them from causing us harm. This project focuses on bacteria on ordinary kitchen cleaning aids: the sponges, dishrags, and scouring pads that you use to wash dishes. Since you usually use them with hot, soapy water, they should stay pretty clean, right? Or not?
Find out how clean your kitchen is with this project investigating the bacterial resistance of ordinary kitchen cleaning materials.
Terms and Concepts
To do this project, you should do research that enables you to understand the following terms and concepts:
- Bacteria
- Disinfectant
Bibliography
- Hinman, A., 1996. What's the Most Unsanitary Spot in Your House? CNN, March 5, 1996. Retrieved October 27, 2006.
- Raloff, J., 1996. Sponges and Sinks and Rags, Oh My! Where Microbes Lurk and How to Rout Them, Science News Online, September 14, 1996. Retrieved October 27, 2006.
- Todar, K., 2002. Growth of Bacterial Populations, Todar's Online Textbook of Bacteriology, Department of Bacteriology, University of Wisconsin, Madison. Retrieved October 27, 2006.
Materials and Equipment
- Used kitchen cleaning aids, e.g.:
- Sponge
- Dishrag
- Scouring pad
- Dishtowel
- Sterile saline solution or sterile liquid bacterial growth medium. You can purchase nutrient media in sterile test tubes from online suppliers such as Carolina Biological Supply Company.
- About 20 sterile test tubes. Note: If you purchase nutrient media in sterile test tubes, then you do not need to purchase these additional sterile test tubes.
- Nutrient agar plates; available from Carolina Biological Supply Company and other online suppliers
- Bacteria loop; available from online suppliers such as Carolina Biological Supply Company
- 37°C incubator
- Disinfecting materials, e.g.:
- Dishwashing soap
- Microwave
- Household bleach solution (5% in water)
- Air drying
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Experimental Procedure
- Do your background research so that you are knowledgeable about the terms, concepts, and questions.
- Distribute the sterile saline solution to sterile tubes (at least 2 tubes per kitchen cleaning material to be tested).
- Cut small samples of each used kitchen cleaning aid and immerse in sterile saline solution. You are going to grow the bacteria that have accumulated in the cleaning aids while in use.
- Label the tubes and incubate 48 hours at 37°C.
- You should also have at least one sterile saline tube with nothing in it as a negative control.
- After 48 h incubation, you will plate samples from each tube. Label a bacterial plate for each saline tube.
- Use a sterile bacteria loop to plate a sample from each saline tube. Flame-sterilize the loop before each use, or use disposable loops, one for each tube.
- Use the quadrant streaking method (see Microbiology Techniques & Troubleshooting).
- Wait 5 minutes for plates to dry, seal with tape, and then incubate (inverted) overnight at 37°C.
- Count the number of colonies in each plate and record results in your lab notebook. The plate from your sterile saline solution should have no colonies.
- Are you surprised at the results?
- Now try the different disinfecting methods on samples of one or more materials. For example:
- Wash with soap and water, then air dry.
- Air dry.
- Microwave.
- Soak in 5% bleach solution, rinse, and air dry.
- Cut small pieces of disinfected samples, immerse in sterile saline solution, incubate 48 hours at 37°C. Again, prepare at least 2 tubes for each disinfection method.
- Make sure you have at least one sterile saline tube with nothing in it as a negative control.
- After 48 h incubation, you will plate a sample from each saline tube. Label a bacterial plate for each saline tube.
- Use a sterile bacteria loop to plate a sample from each sterile tube. Flame-sterilize the loop before each use, or use disposable loops, one for each tube.
- Use the quadrant streaking method (see Microbiology Techniques & Troubleshooting).
- Wait five minutes for plates to dry, seal with tape, and then incubate (inverted) overnight at 37°C.
- Count the number of colonies in each plate and record the results in your lab notebook.
- Which disinfection method worked the best?
- Which disinfection method(s) worked adequately?
- Which disinfection method(s) did not work adequately?
Ask an Expert
Do you have specific questions about your science project? Our team of volunteer scientists can help. Our Experts won't do the work for you, but they will make suggestions, offer guidance, and help you troubleshoot.
Variations
- 3-M company makes bacteria-resistant sponges for kitchen use. Compare these sponges vs. plain sponges. Do the bacteria-resistant sponges really work?
- Compare sponges (or dishrags) that have been used for different lengths of time (brand new, 1-week old, 2-weeks old, 1 month old). When should you throw away that old kitchen sponge?
- Compare wooden vs. plastic cutting boards. On which type of surface do bacteria live longer? Which surface cleans up better with soap and water? Design an experiment to find out.
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Think of all the jobs in the world that involve machinery, chemicals, toxins, radiation, loud noise, or travel to places above or below Earth's surface—all of these jobs carry an element of risk to the workers. Industrial health and safety engineers work to minimize this risk. They inspect work sites and help workers and companies understand and comply with safety laws. They use their knowledge of mechanical processes, chemistry, and human psychology and performance to anticipate…
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Related Links
Cite This Page
General citation information is provided here. Be sure to check the formatting, including capitalization, for the method you are using and update your citation, as needed.MLA Style
Science Buddies Staff.
"Bacterial Resistant Materials and the Best Disinfectant." Science Buddies,
19 Jan. 2023,
https://www.sciencebuddies.org/science-fair-projects/project-ideas/MatlSci_p017/materials-science/bacterial-resistant-materials-best-disinfectant.
Accessed 25 Mar. 2023.
APA Style
Science Buddies Staff.
(2023, January 19).
Bacterial Resistant Materials and the Best Disinfectant.
Retrieved from
https://www.sciencebuddies.org/science-fair-projects/project-ideas/MatlSci_p017/materials-science/bacterial-resistant-materials-best-disinfectant
Last edit date: 2023-01-19
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