LEARNING OBJECTIVES: At the end of the lesson, students will:
1. Define Culturing
2. Describe how to prepare a culture solution
3. List the instruments required and the necessary precautions to be taken in preparing a culture solution
4. Demonstrate culturing and monitor the growth rate of microorganisms.
5. Identify colonies of microbes present in different culturing samples.
KEY VOCABULARY WORDS: Culture, Agar, Microscope, Petri-dish, Inoculating loops, Hand lens, Slides etc.
- Culturing simply involves growing microorganisms in special media in the laboratory. It involves making sterile medium, inoculating, incubating and examining micro-organisms. By this means, micro-organisms' characteristics such as colour, the pattern of growth, and appearance can be seen.
- INSTRUMENTS REQUIRED FOR THE PREPARATION OF CULTURE SOLUTION
● Microscope
● Petri-dishes
● Test tubes and test tube holders
● Slides
● Inoculating loop
● Bunsen burner
● Improvised incubator
Precautions in Preparing Culture Solution
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Ensure Sterility – Work in a clean environment and sterilize all equipment and materials to avoid contamination.
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Use Clean, Accurate Tools – Use distilled water and accurately measure solutes with clean, calibrated equipment.
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Wear Protective Gear – Always wear lab coats, gloves, and goggles to protect yourself and the culture.
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Adjust pH and Mix Properly – Carefully adjust pH if required and ensure all components are fully dissolved.
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Label and Store Correctly – Clearly label solutions and store them under appropriate conditions to maintain quality
Preparation of Culture Solution.
Culture solutions are prepared to provide nutrients for the growth of microorganisms or plant cells. The process involves dissolving specific chemical components such as salts, sugars, and vitamins in distilled water. Accurate measurements are essential. The solution is mixed thoroughly, and the pH is adjusted if necessary. After preparation, the culture solution is sterilized using autoclaving or filtration to prevent contamination. Finally, it is cooled, labeled, and stored in sterile containers for use.
Identification of Colonies of Microbes in Culture Samples.
Microbial colonies in culture samples are identified based on their physical characteristics such as size, shape, color, texture, elevation, and edge (margin). Each type of microbe forms a unique colony appearance on agar media. For example, bacterial colonies may appear smooth and shiny, while fungal colonies are often fuzzy or woolly. Observations are made under proper lighting, and sometimes with the aid of a microscope. Further identification can be done using staining techniques and biochemical tests.
CONTENT: WAYS THROUGH WHICH MICROBES ENTER THE BODY
1. Mouth
2. Nose
3. Broken skin
4. Skin
5. Anus
6. Bite from vector
7. Blood contact
8. At birth
9. Sexual contact
CARRIERS OF MICROORGANISMS
Carriers are agents which are capable of transferring microbes from one place to another. Non - living agents that carry microbes from place to place are air, water and food.
Animals are living agents that transfer microbes from place to place. Animals that carry pathogenic microbes are known as Vectors.
EXAMPLES OF VECTORS , MICROORGANISMS THEY CARRY AND DISEASE CAUSED.
ASSESSMENT:
1. State the ways by which microbes enter into the body
2. Define Vector
3. List examples of Vectors
4. State the microorganisms associated with each Vector and the diseases caused.
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