Practical 9: Antimicrobial properties of plants

Answer 1

1. Carry out aseptic techniques detailed above.
2. Crush 3g of the garlic and mint (separately) with methylated spirit. Shake
   occasionally.
3. Use a sterile pipette to transfer plant extract to paper disc.
4. Leave paper discs to dry for 10 minutes.
5. Use sterile forceps to place the paper disc onto a petri dish.
6. Lightly tape a lid on, invert and incubate at 25°C for 24 hours. DO NOT tape
   around the entire dish as this prevents oxygen entering and so promotes the growth of more harmful anaerobic bacteria.
7. Sterilise equipment used to handle bacteria and disinfect work surfaces.
8. Measure the diameter of the inhibition zone (clear circle) for each plant. DO
   NOT remove lid from agar plate.
9. Work out the area of the inhibition zone

risks- disinfectant, flames

variables-
control= weight of garlic and mint
independent = using mint OR garlic
dependent = range of inhibition

plot data in a table