Growing Bacteria at Home

Introduction: Growing Bacteria at Home

My project is about trying to grow live bacteria samples at home to observe how bacteria grow so that I can answer my main question of, "how do bacteria grow?" and learn the process for my own use in the future.

Step 1: The Problem or Purpose

The purpose of my experiment is to see how bacteria grows and multiplies and how long it takes to do so in a stable and contained environment.

Step 2: The Hypothesis

I hypothesize that the bacteria will grow in one week and that different bacterial colonies will form along the Petri dish

Step 3: The Variables

In my experiment, there are three variables, the dependant variable, the independent variable, and the controlled variable. for my independent variable, it is the bacteria sample that I am exposing the agar to since I am controlling how much bacteria I am exposing the agar to and from where I retrieved that bacteria from. Secondly, my dependant variable is the bacteria I"m growing and the number of bacteria that I will find after the one week period. Finally, my controlled variable is the Petri dish as it has not changed throughout the entirety of the experiment.

Step 4: Background Information

Bacteria are one-celled, or unicellular, microorganisms. They are different from plant and animal cells because they don’t have a distinct, membrane-enclosed nucleus containing genetic material. Instead, their DNA floats in a tangle inside the cell.

Individual bacteria can only be seen with a microscope, but they reproduce so rapidly that they often form colonies that we can see. Bacteria reproduce when one cell splits into two cells through a process called binary fission. Fission occurs rapidly in as little as 20 minutes.

Bacteria are everywhere, and since they reproduce rapidly they are easy to study with just a few simple materials. All you need are some Petri dishes, agar, and sterile swabs. Agar is a gelatinous medium that provides nutrients and a stable, controlled environment for bacteria growth.

Step 5: The Materials

To replicate my experiment, you will need some materials, I have provided them in the list below:

  • A Petri dish (One per sample)
  • Agar powder
  • A bowl
  • Spoon/Whisk
  • Sterile swabs
  • Tweezers
  • Bleach
  • A plastic bag

Step 6: The Procedure

Now that you have all the materials ready its time to start the experiment.

1- Preparing your agar solution:

the first step is to take your bowl and mix in it 1.2 grams of agar powder and 60 milliliters of hot water until combined. Next, place the bowl in the microwave, and let it boil for a minute, make sure it doesn't boil over (you should know it's done when the solution turns clear).

2- Preparing your Petri dish:

Take out your Petri dish and sterilize it all over, then pour your agar solution into the bottom half of your Petri dish, pour just enough to cover the bottom and a little more. then quickly cover the dish with the top part to prevent airborne bacteria from contaminating the sample, and set the agar to cool for 30 minutes - 2 hours.

3- Introducing the bacteria:

After the agar hardens, take out your sterile swabs and collect a sample of bacteria by rubbing the swab on the surface of your choice. After collecting your sample take the sterile swap and rub it directly on the hardened agar to introduce the sample to the agar. Immediately close the lid on the Petri dish to prevent contamination of the sample.

4- Allow the sample to cultivate:

Store your sample in a warm and dark place where the bacteria can develop well for the next 5-7 days, and don't forget to store the dishes upside down, so the bacterial growth remains undisturbed by any water droplets that may form on the top of the Petri dish.

5- Document your results:

After 5-7 days have passed you should be able to see many types of bacteria, mold, and fungi have grown in the agar, if you would like, you can examine the cultivated sample using a pair of tweezers with the utmost caution to not touch or inhale the bacteria as it can pose a risk to you.

6- Disposing of the sample

After conducting your experiments on the sample, it is time to dispose of it as it is no longer of use to you, the correct way to dispose of the sample is by wearing rubber gloves, an apron, a mask, and goggles to prevent any bacteria touching you. Take your sample over the sink and start pouring bleach over it making sure to not let any of the bleach touch your skin, this should kill the bacteria left over, after that place it in a sealed plastic bag and then dispose of it in the trash.

Step 7: The Conclusion and Application

In conclusion, my hypothesis turned out to be correct as there were many different types of bacteria and fungi growing in my sample, and I was able to notice them in a week from when I started.

In this experiment, I learned many things. I learned how to test the effectivity of different antibacterial products and I learned how to differentiate between a fungus and bacteria by eye, and most importantly I learned about the importance of bacteria in our daily lives and how sometimes bacteria can save us. Now that I have completed my experiment I do not plan on stopping my experimentation with bacteria anytime soon as in the future I plan to experiment with a multitude of different antibiotics and document how each one affects the bacteria differently and hopefully when i grow up conduct even more complex experiments.

Step 8: Evaluation

During this project, I benefited a lot from the new information and knowledge I gained.but not only did I benefit from that but I also developed some of my skills, namely the 5 ATL skills which are: research skills, self-management skills, thinking skills, communication skills, and social skill. I used these skills nearly the entire time I was working on the project. I used my research skills when I researching my background information and I also searched to find the data I used in my experiment and the procedures. I used self-management skills when I managed my time to finish my instructable on time. I also used thinking skills when I thought about the idea of my project. And another skill that I used is communication/social skills. I used communication skills and social skills when I communicated and socialized with my uncle who helped me find a good recording program for my introductory video.

Step 9: References (in MLA Format)

1- “How to Grow Bacteria: 5 Experiments to Grow & Test Bacteria.” Home Science Tools, 23 Mar. 2020, learning-center.homesciencetools.com/article/bacteria-experiment-guide/.

2-

3- Juncker, Meredith. “How to Grow Bacteria in a Petri Dish.” WikiHow, WikiHow, 9 Mar. 2020, www.wikihow.com/Grow-Bacteria-in-a-Petri-Dish.

4- “Bacteria: Life History and Ecology.” Life History and Ecology of Bacteria, ucmp.berkeley.edu/bacteria/bacterialh.html.

5- “How Do Bacteria Grow?” Module 2, seafoodhaccp.cornell.edu/blackboard/module2/mod2-09.html.

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    Comments

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    equipoisebob
    equipoisebob

    Tip 1 year ago

    Nice work! I would have included a Petri dish of medium that was not inoculated at the start but incubated along side your experimental plates. This would allow you to assess the quality of your sterilization and aseptic technique, The hypothesis that both sterilization and aseptic technique were both perfect would suggest that no microbial colonies should be found on the control plates while colonies develop on the inoculated plates. This proves that the colonies developed from microbes in the inoculum rather than contaminants in the medium. Looking at your plates there are a lot of sporulating fungi evident. Probably Aspergillus sp. These produce lots of spores that are quite allergenic and some can even cause respiratory infections so take care not to inhale these.

    If you want to go further with 'home microbiology' I suggest you get hold of a pressure cooker and learn how to use it to sterilise things. In general I would give things 15 minutes and 15 psi (121 centigrade) to be sure. Remember things will be hot when they come out of the pressure cooker!