Microbiology
This practical lesson covers:
- The effect of antiseptic or antibiotics on bacterial growth using agar plates and measuring zones of inhibition
Investigating the effect of antiseptic or antibiotics on bacterial growth |
Aim:
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Background information: Antiseptics and antibiotics inhibit or kill bacteria, which can be quantitatively assessed using agar diffusion tests. This practical involves applying these agents to agar plates inoculated with bacteria and measuring the zones of inhibition around filter paper discs. |
Variables:
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What is the purpose of dividing the agar plate into three sections?
to compare the effect of different antiseptics
to measure the diameter of the clear zone
to create a control group
to prevent anaerobic conditions
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Why is it important to wash hands with antibacterial soap before handling the filter paper discs?
to sterilise the filter paper discs
to ensure accurate measurement of the clear zone diameter
to remove any potential contaminants from the hands
to prevent the growth of harmful bacteria
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What is the purpose of incubating the agar plate at 25°C for 48 hours?
to prevent anaerobic conditions
to allow bacteria to grow and form colonies
to compare the effect of different antiseptics
to measure the diameter of the clear zone
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What is the purpose of spraying the work surface with disinfectant?
to sterilise the agar plate
to prevent the growth of harmful bacteria
to clean and remove potential contaminants
to measure the diameter of the clear zone
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