Introduction: Microorganisms are ubiquitous in nature, and they play an essential role in various ecosystems. They can be found in soil, water, and even on the human body. The study of microorganisms is essential in understanding their function, and it helps us to develop ways of controlling their growth. In this practical investigation, we will learn how to grow microbial cultures on agar plates and observe their growth over time.

Keywords: Microbial cultures, Agar plates, Growth, Observations, Microorganisms.

Equipment needed:

• Agar plates
• Sterilized inoculating loop
• Bunsen burner
• Petri dishes
• Incubator
• Microscope

Method:

1. Sterilize the inoculating loop by heating it in the Bunsen burner until it turns red-hot. Allow it to cool before proceeding.
2. Label the agar plates with the name of the microorganism to be cultured.
3. Open the lid of the agar plate, and using the sterilized inoculating loop, gently streak the surface of the agar with the microorganism.
4. Close the lid of the agar plate and incubate it at the appropriate temperature for the microorganism. (e.g., 37°C for bacteria, 25°C for fungi)
5. After 24-48 hours, observe the growth of the microorganism on the agar plate.
6. If necessary, make subcultures by transferring a small amount of the growth to a new agar plate.
7. Observe the subculture after 24-48 hours.
8. Prepare a wet mount of the subculture, and observe it under the microscope.

Calculations and expected findings: There are no specific calculations involved in this practical investigation. The expected findings will depend on the type of microorganism being cultured. Bacteria will typically form colonies that are circular, irregular, or filamentous. Fungi will form colonies that are circular, powdery, or filamentous. Observations will be made on the size, shape, texture, color, and other characteristics of the colonies.

Conclusion: Microbial cultures can be easily grown on agar plates, and their growth can be observed over time. This practical investigation allows us to learn more about the different types of microorganisms, their characteristics, and their growth patterns. It also highlights the importance of aseptic technique in preventing contamination of the cultures.

Questions:

1. What is the purpose of sterilizing the inoculating loop before use?
2. How do you label the agar plates?
3. What is the appropriate temperature for culturing bacteria?
4. How do you observe the growth of the microorganism on the agar plate?
5. What is the purpose of making subcultures?

Answers:

1. The purpose of sterilizing the inoculating loop is to prevent contamination of the microorganism being cultured.
2. The agar plates should be labeled with the name of the microorganism being cultured.
3. The appropriate temperature for culturing bacteria is 37°C.
4. The growth of the microorganism on the agar plate is observed by examining the colony characteristics, such as size, shape, texture, and color.
5. The purpose of making subcultures is to obtain a pure culture of the microorganism for further study.

• Practical Biology