Mixing potato water

Creating Potato Water

Begin by gathering your potatoes and heating a pot of water we'll use for boiling soon.

Cut the potatoes

Cut your unpeeled potatoes into small pieces. Cutting them into smaller pieces will release more nutrients into the water due to more surface area.

Weighing potato slices

Boil the potatoes

Put your cut potatoes into your pot and boil them for 30-60 minutes.

Boiling potato slices

Strain the potatoes

After boiling, use a cheesecloth to strain the potato chunks from the water into a bowl. Save the water, but throw away the potato chunks unless you want to use them for another reason.

Straining slices

Removing potato slices from water

Also, add more water to the bowl to bring the level up to 1/2 liter.

Add ingredients to Erlenmeyer flask

Note: The target amount of water, dextrose, and agar used for this guide should fill about 20 Petri dishes. Adjust the measurements to your liking if you have more or less on hand.

First, add the dextrose and agar to the potato water. Then, add the mixture to the Erlenmeyer flask using a funnel.

Weighing dextrose and agar powder (about 150g)

Adding dextrose and agar powder to the potato water

PDA mixture added to flask

Close the opening of the Erlenmeyer flask

To avoid the mixture boiling out of the flask during sterilization, tightly stuff the opening with nonabsorbent poly-fil.

Flask stuffed with poly-fil

Next, cut a square piece of aluminum foil and cover the poly-fil stuffed opening of the flask. Covering the top with aluminum foil will help prevent water from entering the flask and act as a layer of protection from contamination.

Flask covered with aluminum foil