Potato dextrose agar (PDA) is an all-purpose basal medium for the identification, production, and enumeration of yeast and molds in food and dairy items. It is used for the production of yeasts and molds from scientific samples. Sporulation and pigmentation also promote the growth and screening of pathogenic and non-pathogenic fungi.

Potato dextrose agar is also beneficial for sustaining stock cultures of various dermatophytes. Various antibiotics or acids can be added as selective agents, including chloramphenicol, tartaric acid, and chloramphenicol.

Potato Dextrose Agar (PDA) Principle

Potato Dextrose Agar is composed of dehydrated Potato Infusion and Dextrose that encourages and boosts luxuriant fungal growth. Agar acts as the solidifying agent. Numerous standard procedures employ a definite quantity of sterile tartaric acid (10%) to lower the pH of this medium to 3.5 +/- 0.1, also, this prevents the growth of bacteria. Chloramphenicol, as a selective reagent, can inhibit the overgrowth of bacteria that compete with microorganisms in the mixed sample, while allowing the selective separation of fungi.

Composition of Potato Dextrose Agar (PDA)

Potato infusion 200 g
Dextrose 20 g
Agar 20 g
Distilled water 1 liter

 

Alternative Forms for Supplemented Potato Dextrose Agar

Potato Dextrose Agar with Chloramphenicol
Component Amount
Dextrose 20 g
Potato Extract 4 g
Agar 15 g
Chloramphenicol 25 mg

 

Potato Dextrose Agar with Tartaric Acid
Component Amount
Dextrose 20 g
Potato Extract 4 g
Agar 15 g
Tartaric Acid 1.4 g

 

Potato Dextrose Agar with Chlortetracycline
Component Amount
Dextrose 20 g
Potato Extract 4 g
Agar 15 g
Chlortetracycline 40 mg

 

Potato Dextrose Salt Agar
Component Amount
Dextrose 20 g
Potato Extract 4 g
Agar 15 g
Sodium Chloride 75 g

 

Applications of Potato Dextrose Agar (PDA)

  • Potato Dextrose Agar is useful for the detection of yeasts and molds in dairy goods and prepared foods.
  • It also has applications in the cultivation of yeasts and molds from experimental and scientific samples.
  • Potato Dextrose Agar along with Chloramphenicol is useful for the acute production of fungi from assorted specimens.
  • Potato Dextrose Agar with TA (Tartaric Acid) is more so than often endorsed for the microbiological analysis of food and dairy yields.
  • Potato Dextrose Agar supplemented with Chlortetracycline is suggested for the microbial enumeration of yeast and mold from cosmetics.

Limitations

As potato dextrose agar is an all-purpose and not a differential medium, only probable identification is possible by observing colony morphology. Microscopic inspection and biochemical testing should be embraced to identify isolates to genus and species.

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