CP 09 - Antimicrobial properties

Aim

Investigate the antimicrobial properties of plants, including aseptic techniques for the safe handling of bacteria.

Independent variable

The species plant used

Dependent variable

Zone of inhibition

Equipment list

• Disinfectant spray

• Paper towels

• Agar plate already covered with bacteria

• Filter paper cut into equally sized discs

• Incubator at 25 °C

• Sterile forceps

• Pestle and mortar

• Marker pen

• Tape

• Plant samples

  • Ruler

Method

1. Using the disinfectant spray, clean the workbench and wash your hands thoroughly minimize the risk of contamination in the experiment.

2. Use the marker pen to split the seeded agar plate equally and label respectively on the edge of the plate.

3. Take the first plant sample and place it into the mortar. Use the pestle to grind the plant into a fine paste and then use a syringe to add 10 cm³ of ethanol.

4. Use the sterile forceps to soak a filter paper disc in the solution created for 20 seconds and then place the disc on to the sterile agar plate to dry.

5. Once dry, use the forceps to transfer the disc to the second agar plate which has been seeded with bacterial culture and quickly replace the lid to the agar dish.

6. Tape the lid on at 4 points making it secure but also allowing oxygen to enter so the plate.

7. Then incubate the dish at 25 °C for 48 hours.

8. After the 48 hours have passed use a ruler to measure the diameter of the inhibition zone (clear zone) created around each disc.

9. Find area of each ZOI.