Yeast Extract Peptone Dextrose (YPD or YEPD) Agar

  • Yeasts are unicellular eukaryotes and extensively studied model organism in molecular genetics.
  • They are chemoorganotrophs as they utilize organic compounds as a source of energy.
  • Yeast extract peptone dextrose (YPD or YEPD) Growth Agar is used for the maintenance and propagation of yeasts including S. cerevisiae in various molecular microbiology procedures.
  • YPD functions as a complete medium for yeast growth.

Yeast Extract Peptone Dextrose (YPD or YEPD) Agar

Composition of YEPD Agar

Ingredients Gms/litre
Peptone 20.000
Yeast extract 10.000
Dextrose 20.000
Agar 15.000

Final pH (at 25°C): 6.5±0.2

Principle of YEPD Agar

  • YEPD consists of yeast extract, peptone, and glucose or dextrose.
  • Yeasts grow well on a minimal medium containing only dextrose and salts.
  • The addition of protein and yeast cell extract hydrolysates allows faster growth so that during exponential or log-phase growth.
  • Yeast extract supplies B-complex vitamins and it contains all the amino acids necessary for growth.
  • Peptone acts as the source of nitrogen, vitamins, and minerals.
  • Dextrose serves as the carbon source.
  • This medium supports the vigorous growth of wild type as well as mutant strains of all kinds of budding yeast.

Preparation of YEPD Agar

  1. Suspend 65grams of the powder in 1 liter of purified water.
  2. Mix thoroughly.
  3. Heat the agar medium with frequent agitation and boil for 1 minute to completely dissolve the powder.
  4. Autoclave the agar and broth media at 121°C for 15 minutes.
  5. Cool to 45-50ºC.
  6. Portion equally into Petri plates.

Result Interpretation on YEPD Agar

Organisms Growth
Kluyveromyces lactis Luxuriant growth
Saccharomyces cerevisiae Luxuriant growth; smooth, moist, glistening colonies
Candida albicans Luxuriant growth

 Uses of YEPD Agar

  • YEPD is used as a growth medium to grow yeast cultures.
  • It is used for the growth of Saccharomyces cerevisiae.
  • This medium supports the growth of most heterotrophic microorganisms but due to their simple composition, they have been adopted as the basal media for the routine cultivation of yeasts.
  • It is used for preparing culture media in molecular microbiology procedures.

Limitations of YEPD Agar

  • It is a non-selective medium.
  • By being a complete medium, YEPD cannot be used as a selection medium to test for auxotrophs.



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