Growing Bacteria - Petri Dish

Summary

This video demonstrates a hands-on science experiment highlighting the growth of microorganisms on everyday objects. The presenter shows how bacteria can be found on items like shoes, phones, and keyboards, with a focus on petri dish cultures. Through inoculating surfaces and observing growth, viewers learn about the prevalence of microorganisms and the role of cleanliness. The presenter discusses the implications of sanitizing versus allowing natural microbial growth, with insights from experts on maintaining health through balanced hygiene. The video encourages curiosity about biology and microbiology, especially for science projects.

Takeaways

• 😀 Petri dishes must be handled carefully to avoid contamination from fingerprints and external bacteria.
• 😀 Nutrient agar is used to grow microorganisms; it's a powder that is mixed with water, then solidifies to create a growth medium.
• 😀 Once the petri dish is inoculated with bacteria (by swabbing various surfaces), it should be sealed with tape and not reopened.
• 😀 Common surfaces like keyboards, shoes, and phones can harbor a variety of microorganisms, some of which may be harmful or benign.
• 😀 Microorganisms in the mouth outnumber all mammals on Earth, highlighting the prevalence of bacteria in our daily lives.
• 😀 Surfaces like shoes can be almost as contaminated as your mouth, underlining the ubiquity of bacteria.
• 😀 The presence of bacteria on everyday objects, such as cell phones, may surprise people, but it's part of the natural environment.
• 😀 Over-sanitizing can disrupt the balance of good bacteria that help keep our bodies and environments healthy.
• 😀 It's important to use cleaning products like wipes correctly (one direction only) to avoid spreading bacteria further.
• 😀 Some bacteria and fungi on surfaces may appear concerning, but many are harmless and can exist in balance with our environment.
• 😀 The experiment emphasizes that while sanitation is important, it's equally critical to understand microbiology to avoid overreacting to common microbes.

Q & A

What is the first precaution when handling a petri dish?

The first precaution is to avoid touching the petri dish with your fingers to prevent introducing new bacteria into it.

What is the role of the nutrient agar in the experiment?

The nutrient agar is a powder that is mixed into a solution, which then solidifies in the petri dish. It provides a medium that supports the growth of microorganisms.

How does the nutrient agar harden?

The nutrient agar hardens by cooling after being placed in the petri dish and is prepared by adding gelatin to the mixture.

What does the experimenter do with the petri dish to inoculate it?

The experimenter rubs the petri dish with various items, such as a keyboard or their mouth, to introduce microorganisms. This is done by gently scraping or swabbing the items on the agar surface.

Why is it important to tape the petri dish after inoculation?

Taping the petri dish shut prevents contamination from the outside environment and keeps the dish sealed so microorganisms can grow undisturbed.

What surprising finding is shared about the contamination in different objects?

The experiment reveals that common items like shoes and phones can be more contaminated than expected. For instance, the mouth and shoes showed high levels of microorganisms, even surpassing the contamination on Kim's phone.

What did the experimenter discover about Kim's phone in the experiment?

Kim's phone showed some contamination, but it was not as contaminated as the mouth or shoes, suggesting that phones may not harbor as many microorganisms as other everyday objects.

What can be learned from the experiment about cleaning and sterilizing surfaces?

Sterilizing or washing surfaces too frequently can disrupt the natural balance of microorganisms. While it’s important to maintain hygiene, over-sanitizing can open up opportunities for new invaders to take hold.

What did the students at Wilder Elementary learn from their experiment?

The students learned that surfaces like car steering wheels and phones are commonly contaminated, and they emphasized the importance of using sanitizing wipes correctly—one direction only to avoid spreading contamination.

Why is it recommended to only use a sanitizing wipe in one direction?

Using a sanitizing wipe in one direction helps to avoid spreading bacteria or germs back onto the surface, ensuring that the cleaning process is more effective.