Objective
By the end of this lesson, you will be able to grow bacteria from water samples and understand the basic principles of microbiology.
Materials and Prep
- Plastic petri dishes
- Agar powder
- Distilled water
- Inoculating loop or sterile cotton swabs
- Water samples (e.g., pond water, tap water, etc.)
- Incubator or warm location (around 37°C)
- Microscope (optional)
Prior knowledge required: Basic understanding of scientific method and laboratory safety.
Activities
- Prepare the agar plates by following the instructions on the agar powder package. Allow the agar to cool and solidify in the petri dishes.
- Collect water samples from different sources, such as a pond, tap, or rainwater.
- Using a sterile inoculating loop or cotton swab, gently swab the water sample onto the agar surface in the petri dish.
- Seal the petri dishes with their lids and place them in an incubator or a warm location (around 37°C) to allow bacterial growth.
- Observe the petri dishes daily for several days. Record any changes in the appearance of the agar and the presence of bacterial colonies.
- (Optional) If you have access to a microscope, you can take a small sample from a bacterial colony and observe it under the microscope to see the individual bacteria.
Talking Points
- "Microorganisms, including bacteria, are everywhere around us, even in water."
- "Agar is a gel-like substance derived from seaweed that provides a solid surface for bacteria to grow on."
- "Different water sources may contain different types and amounts of bacteria."
- "Bacteria reproduce by dividing into two cells, which is why we can see colonies forming on the agar."
- "By observing the changes in the agar and the presence of bacterial colonies, we can learn about the diversity and abundance of bacteria in different water samples."
- "Always handle the petri dishes and water samples with care to avoid contamination and follow proper laboratory safety protocols."