Science Buddies: "Ask an Expert"

We are currently writing a research paper, and this is the method our teacher recommended us. We are testing if a leaf extract can inhibit the growth of a fungi. It goes like this:

The agar culture medium will be made by dissolving 19.5 grams of it in 500 mL of distilled water in a container. It will be sterilized in an autoclave at 121°C and 15 psi for 15 minutes. Afterwards, (leaf extract) will be added and allowed to cool for 20 minutes at room temperature before being dispensed onto the petri dish.

The fungi will be settled in different petri dishes with the agar and leaf extract using a sterilized cork. The fungi will be subjected to the agar disc, then it will be placed onto the separate petri dishes. After a while, 20 mL of the agar will be combined with 1 mL of 25% leaf extract. The agar disc containing the fungi will be placed at the center of the petri dishes containing different treatments. The petri dishes will be properly sealed and stored in an isolation room for 7 days at 17°C.

I don't know what method is being used. But it sounds like the Agar Well Diffusion Method.

Hi,

I hope you're having a great day! Thanks for your question.

Based on the protocol you described, this sounds like the Agar Well Diffusion Assay or the Disk-Diffusion method. They are very similar and both can be used to determine antimicrobial activity -- in the Agar Well assay, the test compounds are added to wells created in the agar, while in the disc-diffusion method, filters containing test compound are placed on the agar.

Hope this helps!
-Brandi