Potato Dextrose Agar is used for the cultivation and enumeration of yeasts and molds.
Potato Dextrose Broth is used for cultivating yeasts and molds.
SUMMARY AND EXPLANATION
Potato Dextrose Agar is a general purpose medium for yeasts and molds that can be supplemented with acid or antibiotics to inhibit bacterial growth. It is used in plate count methods when testing food, dairy products and cosmetics. The USP lists Potato Dextrose Agar as one of the recommended media for use in the Microbial Enumeration Tests when testing nonsterile pharmaceutical products.
Potato Dextrose Agar can be used to grow clinically significant yeasts and molds. In addition, this medium is used to stimulate sporulation (slide preparations), maintain stock cultures of certain dermatophytes and differentiate atypical varieties of dermatophytes by pigment production.
Potato Dextrose Broth is a general-purpose broth medium for yeasts and molds (Potato Dextrose Agar without the agar).
Potato starch, potato infusion and dextrose support luxuriant growth of fungi. Lowering the pH of the medium to approximately 3.5 with sterile tartaric acid achieves the inhibition of bacterial growth. It is important, however, to avoid heating the medium after it has been acidified because this action results in the hydrolysis of the agar and impairs its ability to solidify.