Required Practical 2

Question 1

Describe how to prepare a lawn plate of bacteria

Answer 1

1. Set up and clean working area using disinfectant spray and paper towels.
2. Wash hands with antibacterial hand wash.
3. On the bottom of nutrient agar plate, divide and plot a dot into the middle of three equal, numbered sections with your initials, the date and the name of bacteria on the edge, using a wax pencil.
4. Turn Bunsen burner flame to blue.
5. Open and flame neck of bacteria culture bottle.
6. Use a disposable pipette to take around 1ml of bacteria culture, pass flame the neck of bottle again and close.
7. Slightly open Petri dish on bunsen burner side
8. Pipette the bacteria onto agar plate, close the petri dish and discard the pipette.
9. Dip glass spreader into ethanol, pass it through yellow flame, allow flame on it to go out and for it to cool for 20 seconds.
10. Slightly open petri dish on Bunsen burner side.
11. Spread bacteria around the plate using glass spreader, closing the lid after.

Question 2

Describe how to test the effectiveness of different antiseptics or antibiotics.

Answer 2

1. Dip paper disk into separate antiseptics and place into plate by opening petri dish slightly near bunsen burner - note which antiseptic is in which zone.
2. Slightly secure lid using adhesive tape and incubate upside down at 25ºC for 48 hours.
3. Measure and record the diameter of the clear zones both vertically and horizontally to calculate mean diameter.