Sterile Agar Preparation Guide
Included
- 500ml HDPE Bottle
- 60ml Agar Powder Bottle
- 20x Sterile Petri Dishes
- 20x Laboratory Sealing Film Strips
- 2 Pairs of Gloves
- 10 Cotton Swabs
You Provide
- Distilled Water
- Microwave or Pressure Cooker
- 70% Isopropyl Alcohol (to clean your surface)
- Measuring Cup
Section 2: The Setup
- Mix: Empty the entire 30ml bottle of agar powder into the 500ml media bottle.
- Fill: Using a measuring cup, add 500mL of room-temperature distilled water.
- Swirl: Secure the cap and swirl gently. Continue until the powder is completely dissolved and the mixture is uniform.
- Vent: Tighten cap, then back it off one full turn so it is loose.
⚠️ SAFETY FIRST: VENT THE CAP!
Never heat the bottle with the cap tightened.
Always unscrew one full turn before heating.
Never heat the bottle with the cap tightened.
Always unscrew one full turn before heating.
Section 3: Heating Methods
Option A: Microwave
- Heat on High (cap loose!) for 1 minute. Watch for foaming!
- Remove (use mitt!) and swirl.
- Heat in 30s bursts until liquid is semi-clear and bubbles are rising rapidly.
- Use mitts when removing—bottle will be extremely hot!
Option B: Pressure Cooker
- Place the bottle (cap loose!) into your pressure cooker with 1-2 inches of water in the pot.
- Bring to 15 PSI (Set Pressure Cook to Normal and Pressure Level to Low) and maintain for 10 minutes.
- Allow the cooker to depressurize naturally before opening.
- Use mitts when removing—bottle will be extremely hot!
Section 4: The Pour
- Cool Down: While the lid cap is still loose, let sit until cool to the touch (~115°F / 45°C) for about 10-15 minutes. Tip: Pouring hot causes excess condensation.
- Pour: Gently swirl the bottle to re-mix. Open the petri dish lid slightly, fill bottom of dish (10-12ml), and replace the top. Continue to fill petri dishes until you've run out of agar.
You may see some condensation when you replace the top. This is okay.
Section 5: Swabbing & Storage
- Swab: Firmly rub a sterile swab over a surface (phone, keyboard, door handles, etc).
- Inoculate: Streak the swab in a "Z" pattern on the agar. Do not puncture. Promptly replace the lid and label the dish with the swabbed surface and the date.
- Prepare Laboratory Sealing Film: Cut the Laboratory Sealing Film horizontally along the top dotted line. Then fold the strip in half. Open it back up again and carefully separate the Laboratory Sealing Film strip from its white paper backing.
- Seal: Refold the film along the existing crease and wrap it around the edge of the closed petri dish. Secure one end with your thumb and stretch the film as you wrap to ensure a tight, hermetic seal. Firmly press the overlapping ends together for a few seconds to a minute to bond them.
- Store: Place in a cool, dark place and wait a few days.
