1. Precautions that can be taken when handling micro-organisms
Open all containers for the shortest possible time. Open lids the shortest possible distance.

2. Precautions that can be taken when handling micro-organisms
Seal all plates once inoculated.

3. Precautions that can be taken when handling micro-organisms
Label all plates once prepared.

4. Learning Check What is meant by asepsis? What is meant by sterile?
State 3 precautions that should be taken when handling micro-organisms.
State two ways in which equipment can be sterilised.

5. How to grow a culture.

6. Take a sterile agar plate.
Flame an inoculating loop to sterilise it.
Dip the loop into sterile water or alcohol to cool it.

7. Flame the neck of the container from which the sample is to be taken.
Inoculate the loop by placing it briefly into the sample to be grown.
Re-flame the neck of the container.

8. Sterilise the loop again by flaming it.
While only slightly opening the agar plate streak the inoculating loop across the surface of the agar.
Sterilise the loop again by flaming it.

9. Label and seal the petri-dish and incubate it upside down for 2 - 3 days.
Examine the plate and record the results.

10. Growth
Once the plates are sealed and labelled turn them upside down and place them in an oven (incubator) to allow any bacteria and fungi to grow.
Placing them upside down reduces problems due to condensation

11. Yeasts and moulds grow best at 25 - 30°C.
Bacteria generally require 35°C.

12. Examine the plate and record the results

13. Bacterial colonies are usually seen as white, cream or yellow shiny dots
Fungal colonies appear as a powder or as a fuzzy growth, similar to cotton wool in appearance

14. Disposal
All micro-organisms should be destroyed after use by sterilising all petri-dishes and equipment:
by placing them in an autoclave (or pressure cooker) at 120°C for 15 minutes
or by placing them in Dettol for 24 hours.

15. Syllabus

16. Depth of treatment Precautions when working with micro-organisms.
Asepsis and sterility: definition of each term as applied to living organisms.
Containment and disposal.