Light Malt Extract Agar Recipe

Light malt extract agar (LMEA) is the most straightforward and fundamental formula for creating agar. There's nothing fancy about it, only agar-agar, nutrients, and water. Even in its simplicity, the recipe is highly effective and great for beginners.


  • Water: Distilled, Purified, or tap.
  • Agar-Agar: To obtain the desired jello-like consistency, we use a substance called agar-agar. It is derived from red-algae and can be purchased at Asian grocery stores or anywhere that sells laboratory supplies. Try to find it in a powder form since we are dissolving it in water.
  • Light Malt Extract (LME): This is the nutrient source for the agar mixture. It comes in powdered and liquid form. I've only worked with the powdered version and recommend using it. LME is considered a brewing supply for beer.
  • Food Coloring optional: Typically, agar is a pale yellow color. Food coloring can add additional contrast and help to differentiate experiments. From my experience, the addition of food coloring has no ill effects on the final product.
Ingredient Ratios
Water Agar LME Plates
250 ml 5 g 7.5 g ~10
500 ml 10 g 15 g ~20
750 ml 15 g 22.5 g ~30
1000 ml 20 g 30 g ~40
1250 ml 25 g 37.5 g ~50
1500 ml 30 g 45 g ~60
1750 ml 35 g 52.5 g ~70
2000 ml 40 g 60 g ~80


  • Glass Vessel: Select the glass container with a lid to hold the agar mixture (Mason jar, booze bottle, Erlenmeyer flask, etc.)
  • Pressure Cooker: You'll need to sterilize the agar mixture within a pressure cooker or autoclave.
  • Foil: Prevents moisture from seeping into the mixture when pressure-sterilizing.
  • Digital Scale optional: For accurate measurement of ingredients, I suggest using a digital scale that measures a hundredth of a gram.
  • Infrared Thermometer optional: Highly recommended for monitoring the agar mixture's temperature while it cools.
  • Oven Gloves optional: Protects your hands and allows for better dexterity and grip while handling the hot mixture.
  • Glass Measuring Cup optional: Any glass graduated vessal will surffice. You'll need it to measure boiling water.
  • Funnel optional: Comes in handy if using a narrow-mouthed container.

Creating the Agar Mixture

While this is the most common agar recipe, my method for making may be different from other sources. It works well for me, and feel free to take any liberties to make the recipe your own.

  1. Boiling Water

    Bring a few quarts of water to a boil. Use more water than is needed as some may evaporate, which would throw off the recipe. You can also use the extra water to essentially pre-heat the pressure cooker.

  2. Dry Agar Ingredients
    Dry Ingredients

    Use the ratio table above and measure the needed amount of light malt extract and add it to the empty container. Repeat the process with the agar-agar.

  3. LMEA combine wet and dry ingredients

    Carefully measure the needed amount of boiling water and pour it with the dry ingredients.


    The bottle will be extremely hot.

  4. Agar with food coloring
    Food Coloring Optional

    If you would like to change the mixture's color, add a few drops of the desired color. You may want to avoid using greens as it may disguise contamination.

  5. Mix the agar

    Mix the agar until the dry ingredients are fully dissolved. Do not let the liquid come into contact with filters or poly-fil.


    The bottle will be extremely hot.

  6. Agar bottle with foil
    Pressure Cooker

    Cover the cap of the agar mixture with foil to prevent moister from entering while in the pressure cooker.

    • Begin preparing your pressure cooker.
    Pressure Cooker Tutorial
  7. Agar in pressure cooker

    Place the agar mixture in the pressure cooker and ensure it is secure. If needed, place a few empty mason jars inside the pressure cooker to prevent anything from moving.

  8. Pressure cooker 15PSI

    Cook for at least 45 minutes at 15-PSI. It is perfectly acceptable to cook along with grain spawn. The extended cooking time will not harm the agar.

    • This is a great time to start the sterilization protocol.
  9. Infrared Thermometer Gun

    Allow the pressure cooker to come down to 0-PSI before cracking the seal.

    • Unlike other materials, you'll want to remove the agar mixture from the cooker to prevent it from solidifying.
    • Place the agar in a sterile environment while cooling.
    • The mixture is ready to pour once the temperature reaches 116-122°F (46-50°C).
    • Highly recommend using an infrared thermal gun to monitor the temperatures.


    The bottle will be extremely hot.

Now, you are ready to pour your mixture into petri dishes. You must follow the sterilization protocol for the next part. It is a good idea to prep while the agar mixture is cooking.