What is the best Agar for Mushroom Work?

Agar is Agar is Agar, right? Well, no not exactly. While a simple gelatin and carbohydrate mix will grow almost anything and can be used as a “catch-all” for most mycological work, if you are looking to step up your game, adopting an agar recipe to the culture you are attempting to grow will have profound impacts on the results you are trying to achieve.

What is Agar?

Agar is a gelatinous substance used in cooking and other industries as a thickening agent. The most recognizable product which demonstrates what Agar is would be Jello.  

Although the Agar itself is non-nutritious, by combining it with other nutrients, this gelatinous substance is a wonderful medium to use when growing bacteria, molds, and other microorganisms. 

Different agar recipes for different uses

So what is the best agar recipe for mushroom work? Well, that depends. You may certainly use a simple balanced agar blend as a catch-all, however, there are certain blends that work better during different stages, i.e. spore germination, transfers, culture cleanup, and cloning live fruits. That said, below are a few common agar recipes used at different times during culture work.

Best Agar for Spore Syringes, Spore Prints, or Swabs

When using agar to clean up spore prints, or to germinate spores, you will want to use a nutritionally balanced agar recipe using simple sugars and light in color.

PDA – Potato Dextrose Agar

Potato Dextrose Agar (PDA) is a general-purpose medium for the cultivation of fungi, yeasts, and molds. PDA is a blend of agar, potato starch and simple sugars. PDA may be supplemented with acid or antibiotics to inhibit bacterial growth.

MEA – Malt Extract Agar

Light Malt Extract Agar is one of the most straightforward and common formulas used for fungi. MEA is a blend of agar powder and simple sugars derived from grain. The light color and simplicity of this recipe make it wonderful for germination and identifying potential contaminates.

Best Agar for Taking Culture Transfers and Cloning Mushrooms

While a simple PDA or MEA agar will work just fine for most all mushroom culture work, you may adjust your agar recipe by adding specific nutritional additives to promote more aggressive mycelial growth.  

When making transfers, cloning live fruits, or cleaning up cultures, many growers will use specialized agar blends which are formulated to provide a nutrient-rich medium with additives to accelerate mycelial growth. There are many different recipes one can use, however, the most common will be a variation of MEA or PDA with added ingredients such as yeast. 

Malt Extract or Potato Dextrose with Yeast and Peptone

Building on the MEA or PDA recipes, these blends also include Yeast and Peptone which increases the nutritional content of the medium.

NOTE: Modifying the nutritional content of your agar dishes is a method used to promote stronger and more aggressive growth. For example, lowering the concentration of nutrients in the plate will starve the culture, promoting a stronger, more versatile mycelium culture sample.

Enhanced Activated Carbon Agar (Black Agar)

Also known as Black Agar, Activated Carbon agar is an agar medium that uses activated carbon aka activated charcoal as a dye, which turns the agar black in color, providing exceptional contrast against growing mycelium. The most common black agar will be made using the above-mentioned MEA or PDA with Yeast, Peptone, and a dash of Activated Carbon. Enhance AC Agar provides a nutrient-dense growth environment and is exceptional for showcasing mycelial growth.

Interested in making your own agar? Below are the recipes mentioned in this article.

For preparation instructions, see this great article by bitesizebio.com

Agar Recipes:

The recipes listed below will make approximately 20 100mm Petri dishes. Adjust accordingly if you need more or less. 

Malt Extract Agar MEA

  • 500 ml Distilled H20
  • 10g Agar powder
  • 10g Malt Extract Powder

Potato Dextrose Agar PDA

  • 500 ml Distilled H20
  • 10g Agar powder
  • 7g Dextrose
  • 2g Potato infusion/extract

Nutrient Agar – Not typically used for fungal cultures

  • 500 ml distilled H20
  • 12g premixed nutrient agar powder

Malt Extract with Yeast and Peptone

  • 500 ml distilled H20
  • 10g Agar powder
  • 10g Malt extract
  • 1g Peptone
  • 1g Yeast extract

Potato Dextrose Agar with Yeast and Peptone

  • 500 ml distilled H20
  • 10g Agar powder
  • 7g Dextrose
  • 2g Potato infusion/extract
  • 1g Peptone
  • 1g Yeast extract

Malt Extract with Yeast, Peptone, and Activated Carbon  

  • 500 ml distilled H20
  • 10g Agar powder
  • 10g Malt extract
  • 1g Peptone
  • 1g Yeast extract
  • 1g Activated Carbon/Activated Charcoal

Potato Dextrose Agar with Yeast, Peptone, and Activated Carbon  

  • 500 ml distilled H20
  • 10g Agar powder
  • 7g Dextrose
  • 2g Potato infusion/extract
  • 1g Peptone
  • 1g Yeast extract
  • 1g Activated Carbon

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