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Potato Dextrose Agar (PDA) Media

Potato Dextrose Agar (PDA) is a microbiological medium for cultivating various fungi. It is a general-purpose medium commonly used in the field of microbiology. The abbreviated name for this medium is PDA, where ‘P’ stands for Potato, ‘D’ stands for Dextrose, and ‘A’ stands for Agar. PDA is mainly utilized for the examination of yeast and mold counts in food and dairy products. In this post we will discuss in details about Potato Dextrose Agar (PDA) Media.

Potato Dextrose Agar (PDA) Principle:

The principle behind Potato Dextrose Agar involves incorporating dextrose (glucose) as a carbohydrate source, which serves as a growth stimulant. The infusion of potato provides abundant nutrients for the luxurious development of most fungi. Agar, added as a solidifying agent, creates a stable surface for observing the growth and size of microorganisms.

Fungal Growth on Potato Dextrose Agar (PDA) Medium
Fungal Growth on Potato Dextrose Agar (PDA) Medium

The composition of PDA includes three main components:

  1. Potato Infusion (Potato broth): Rich in carbohydrates, especially starch, it serves as the primary carbon and energy source for microorganisms. It also provides essential nutrients like carbohydrates, potassium, magnesium, vitamin C, and vitamin B6 for fungal growth.
  2. Dextrose (Glucose): Dextrose, a carbohydrate source in PDA, provides additional energy and enhances fungal sporulation and pigment production.
  3. Agar: Agar is a gel-forming substance derived from marine algae. It solidifies the medium, creating a stable surface for the development and observation of microorganisms.

Composition of Potato Dextrose Agar (PDA)

Preparing Ourself

Composition of Potato Dextrose Agar

Preparation of Potato Dextrose Agar (PDA) Medium:

PDA medium preparation can be in two ways:

  1. Ready-made PDA powder in the dehydrated form from many companies are available in the market. Example Potato Dextrose Agar (PDA) Medium by Himedia . Follow the instructions provided on bottle for to prepare the medium.
  2. Homemade PDA:
    • Prepare Potato Infusion by boiling 200 grams of peeled and chopped potatoes in 1 liter of distilled water.
    • Strain the solution, and mix it with 20 grams of dextrose and 15-20 grams of agar in a conical flask.
    • Adjust the volume to 1000 ml with distilled water.
    • Sterilize the mixture in an autoclave at 121°C for 15 minutes.
    • Pour the solidified medium into petri plates and refrigerate.

Applications of PDA: PDA is used for:

  1. Food microbiology: Detection of yeast and molds in dairy and food products.
  2. Cosmetics: Enumeration of yeast and molds in beauty products using PDA and chlortetracycline.
  3. Clinical specimens: Identification of yeast and molds in clinical samples.
  4. Many recommend using PDA with chloramphenicol for selectively cultivating fungi from mixed samples.

Image Credit: Silk666, CC BY-SA 3.0, via Wikimedia Commons

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