Potato Dextrose Agar (PDA)

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Introduction

Potato Dextrose Agar, often notated as PDA, is a common microbial growth media made from an infusion of potato and dextrose. It is one of the most widely used media for growing fungi and bacteria. PDA can be supplemented with different acids or antibiotics to inhibit bacterial growth that may interfere with yeasts and mold.  It is recommended for isolation and microbial enumeration of yeasts and molds in dairy, cosmetics, and clinical samples. 

The nutritionally rich base from the potato infusion encourages mold sporulation and pigment production in certain dermatophytes while dextrose supports a general growth of microorganisms. Agar is used as the solidifying agent. 

Reconstitution

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Preparation of Potato Dextrose Agar

  1. Boil 200 g of sliced unpeeled potatoes in 1 liter of water for 30 minutes.
  2. Filter through cheesecloth, saving effluent, which is potato infusion.
  3. Add dextrose, agar, and water to effluent. Boil to dissolve completely. 
  4. Sterilize media by autoclaving at 121ºC for 15 minutes. 
  5. Aseptically dispense into sterile Petri dishes.

Preparing from commercial powder

  1. Add 39 g of commercialized powered to 1 liter of distilled water.
  2. Boil while mixing to dissolve completely.
  3. Sterilize media by autoclaving at 121ºC for 15 minutes. 
  4. Aseptically dispense into sterile Petri dishes.

Alternative recipes for supplemented Potato dextrose agar

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Appearance: Light amber colored clear to slightly opaque gel

pH: 5.6 ± 0.2

Storage

Media is both light and temperature sensitive. Store plates away from direct light at 2-8ºC. Plates may be used for one week when stored in a clean sterile area. Media should not be used if any signs of deterioration, contamination, and/or expiration date has passed.  

STERILIZE ALL BIOHAZARD WASTE BEFORE DISPOSAL.


References

  1. Aryal, Sagar, et al. “Potato Dextrose Agar (PDA)- Principle, Uses, Composition, Procedure and Colony Characteristics.” Online Microbiology Notes, 11 June 2018, http://microbiologyinfo.com/potato-dextrose-agar-pda-principle-uses-composition-procedure-and-colony-characteristics/.
  2. Center for Food Safety and Applied Nutrition. “Laboratory Methods - BAM Media M127: Potato Dextrose Agar.” U S Food and Drug Administration Home Page, Center for Biologics Evaluation and Research, http://www.fda.gov/Food/FoodScienceResearch/LaboratoryMethods/ucm063519.htm.
  3. "Potato Dextrose Agar" Acumedia.  Neogen. http://foodsafety.neogen.com/pdf/acumedia_pi/7149_pi.pdf
  4. “POTATO DEXTROSE AGAR.” Kligler Iron Agar (KIA) - or the Identificaiton of Enteric Bacteria, http://catalog.hardydiagnostics.com/cp_prod/Content/hugo/PotatoDextroseAgar.htm.
  5. "Potato Dextrose Agar" Himedia Labs. Technical Data. http://himedialabs.com/TD/M096.pdf
  6. “Potato Dextrose Agar (PDA): Principle, Composition and Colony Characteristics -.” Home -, 31 May 2015, http://microbeonline.com/potato-dextrose-agar-pda-principle-composition-colony-characteristics/.